JP3406959B2 - Method for forming deposited film by microwave plasma CVD method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a deposited film forming method by a microwave plasma CVD method in which a raw material gas for forming a deposited film is decomposed by microwave energy to form a deposited film on a substrate, and more particularly to a photovoltaic device. , A thin film transistor, a sensor, a photoreceptive member for electrophotography and the like, and a functional deposited film forming method suitable for the same.

The present invention also relates to microwave plasma CVD.
The present invention relates to an apparatus for forming a functionally deposited film by the method, and more particularly to an apparatus for continuously forming a photovoltaic element such as a solar cell. More specifically, the present invention relates to an apparatus for mass-producing photovoltaic elements such as solar cells using the roll-to-roll method.

[0003]

2. Description of the Related Art Conventionally, a plasma CVD method is generally widely used for forming a functional deposited film such as a photovoltaic element using an a-Si film, and has been commercialized. There is.
However, in order to establish this as a photovoltaic element that can meet the power demand, the photovoltaic element to be used must have sufficiently high photoelectric conversion efficiency and excellent characteristic stability, and be mass-produced. It is basically required to be able to do. To this end, in film formation of a photovoltaic element using an a-Si film or the like, electrical, optical, photoconductive or mechanical characteristics and fatigue characteristics in repeated use or use environment characteristics are improved. At the same time, it is necessary to achieve reproducible mass production by high-speed film formation while achieving a large area and uniform film thickness and film quality. .

From such a point of view, many reports have been made on the method of forming a deposited film by the microwave plasma CVD method.

For example, "Chemical Vapor
deposition of a-SiGe: Hf
ilms utilizing a microvav
e-excited plasma "T. Watana
be, M .; Tanaka, K .; Azuma, M .; Nak
atani, T .; Sonobe, T .; Simada, J
apanese Journal of Applie
d Physics, Vol. 26, No. 4, Apr
il, 1987, pp. L288-L290, "Mic
rowave-excited plasma CVD
of a-Si: H films utilizin
ga adrogen plasma strea
m or by direct excitation
ofsilane "T. Watanabe, M. Ta
naka, K .; Azuma, M .; Nakatani,
T. Sonobe, T .; Simada, Japanes
eJournal of Applied Physi
cs, Vol. 26, No. 8, August, 198
7, pp. 125-1218 and the like describe a microwave plasma CVD method using ECR.

Further, Japanese Patent Laid-Open Publication No. 59-16328 “Plasma vapor phase reactor” and Japanese Laid-Open Patent Publication No. 59-567.
24 "Microwave plasma thin film formation method"
A method of depositing a semiconductor film by a microwave plasma CVD method is shown.

Further, in the rf plasma CVD method, a method of forming a deposited film in which a mesh-shaped third electrode is provided between an anode and a cathode is "Preparation of".
highly photosensitive hy
drowned amorphous Si-G
e alloys using a triodepl
asma reactor "A.Matsuda e
t. al. , Applied Physics Let
ters, Vol. 47 No. 10,15 Novem
ber 1985 pp. 1061-1063.

Further, in a power generation method using a photovoltaic element, a form in which unit modules are connected in series or in parallel and unitized to obtain a desired current and voltage is often adopted. Is required not to cause disconnection or short circuit. In addition, it is important that there is no variation in output voltage or output current between modules. For this reason, at least at the stage of forming the unit module, it is required to secure the characteristic uniformity of the semiconductor layer itself, which is the largest characteristic determining factor. Further, from the viewpoint of facilitating the module design and simplifying the module assembling process, it is possible to provide a semiconductor deposited film having excellent property uniformity over a large area, thereby improving the mass productivity of photovoltaic devices. It is required to increase the production cost and to significantly reduce the production cost.

In the photovoltaic element, a semiconductor layer which is an important component thereof has a semiconductor junction such as a so-called pn junction or pin junction. When a thin film semiconductor such as a-Si is used, phosphine (PH ₃ ) and diborane (B ₂
A raw material gas containing an element serving as a dopant such as H ₆ ) is mixed with silane, which is a main raw material gas, and glow discharge decomposed to obtain a semiconductor film having a desired conductivity type. It is known that the aforementioned semiconductor junction can be easily achieved by sequentially forming semiconductor films. From this fact, in forming an a-Si photovoltaic element, an independent film forming chamber for forming each semiconductor layer is provided, and each semiconductor layer is formed in the film forming chamber. A method of doing is proposed.

Incidentally, US Pat. No. 4,400,409 discloses a roll-to-roll (Roll to R) method.
There is disclosed a continuous plasma CVD apparatus adopting the Oll system. According to this apparatus, a plurality of glow discharge regions are provided, and a sufficiently long flexible substrate having a desired width is arranged along a path through which the substrates sequentially pass through the glow discharge regions. It is said that an element having a semiconductor junction can be continuously formed by continuously transporting the substrate in the longitudinal direction while depositing a conductive type semiconductor layer required in the discharge region. In this specification, a gas gate is used to prevent the dopant gas used in forming each semiconductor layer from diffusing and mixing into another glow discharge region. Specifically, the glow discharge regions are separated from each other by a slit-like separation passage, and the separation passage is provided with, for example, A
Means for forming a film of a flow of scavenging gas such as r or H ₂ is adopted. For this reason, this roll-to-roll system is a system suitable for mass production of semiconductor devices, but as described above, in order to popularize a large number of photovoltaic devices, further photoelectric conversion efficiency, characteristic stability, and It is desired to improve property uniformity and reduce film formation cost.

In particular, in order to improve the photoelectric conversion efficiency and the characteristic stability, the photoelectric conversion efficiency and the characteristic deterioration rate of each unit module should be improved in 0.1% increments (corresponding to about 1.01 times in proportion). Of course, when the unit modules are connected in series or in parallel and made into a unit, the unit module having the minimum current or voltage characteristic among the unit modules constituting the unit is the rate-determining unit. Because the characteristics are determined,
Not only improve the average characteristics of each unit module,
It is very important to reduce the characteristic variation. Therefore, it is desired to secure the characteristic uniformity of the semiconductor layer itself, which is the largest characteristic determining factor, at the stage of forming the unit module. Further, in order to reduce the film formation cost, it is strongly desired to improve the yield by reducing defects in the semiconductor layer so that disconnection or short circuit does not occur in each module.

Therefore, in the deposition of the semiconductor layer on the continuously moving strip-shaped member, the uniformity of the characteristics is ensured,
It is desired to provide a manufacturing device at an early stage to reduce defects.

[0013]

However, the conventional method of forming a deposited film by the microwave plasma CVD method has the following problems.

(1) For example, when a non-single crystal semiconductor film (for example, amorphous silicon a-Si: H) is deposited, the deposition rate is slow, the electrical characteristics are poor, and the film is used for a long time under light irradiation. There was a problem that there was a lot of deterioration. In particular, when the deposition rate was increased, the electrical characteristics of the semiconductor film, the adhesion to the substrate, and the like were significantly deteriorated.

(2) There is a problem that the plasma is unstable in a region where the raw material gas for forming the deposited film is small.

(3) The plasma is likely to be non-uniform, and the thickness and characteristics of the deposited film formed are likely to be uneven, resulting in device characteristics such as solar cells, thin film transistors, and electrophotographic light-receiving members. There is a problem that the yield is reduced.

(4) During the formation of the deposited film, there are many damages to the surface of the deposited film by unnecessary ions and electrons which adversely affect the structure of the film and the characteristics of the deposited film. Also, there is a problem in that the characteristics become poor.

Therefore, the present invention has been made in view of the above problems of the prior art, and an object thereof is to solve the following problems.

(1) To provide a method for uniformly and stably forming a deposited film of a non-single-crystal semiconductor film, which has excellent electric characteristics even when the deposition rate is increased to 1 nm / sec or more and has little photodegradation.

(2) By increasing the uniformity and stability of plasma, the uniformity of the thickness and characteristics of the deposited film formed,
Provided is a method of improving reproducibility and, as a result, improving device characteristics and yield of photovoltaic elements, thin film transistors, sensors, electrophotography, etc., and reducing the manufacturing cost of these electronic devices.

(3) While suppressing the occurrence of abnormal discharge that adversely affects the characteristics of the deposited film, active species having energy that effectively contributes to structural relaxation of the film during the formation of the deposited film are uniformly supplied over a large area. It is possible to uniformly form a deposited film having desired characteristics by reducing damage to the surface of the deposited film by unnecessary ions and electrons that adversely affect the characteristics of the deposited film. Provided is a deposited film forming method capable of improving the yield and characteristics of devices.

[0022]

[Means for Solving Problems] (1) to (3)
The present invention that achieves the above object is a deposited film forming method as described below. That is, (1) In a microwave plasma CVD method in which a raw material gas for forming a deposited film is decomposed by microwave energy under a low pressure to form a deposited film on a substrate, the raw material gas is 100 % Microwave energy smaller than the microwave energy required for decomposition is applied to the raw material gas, and at the same time, rf energy larger than the applied microwave energy is applied to the raw material gas, and Forming a deposited film by a microwave plasma CVD method, characterized in that a mesh made of a conductive metal is interposed between a space in which a source gas is mainly decomposed and a substrate, and a DC bias voltage is applied to the mesh. Method.

(2) In a microwave plasma CVD method in which a raw material gas for forming a deposited film is decomposed by microwave energy under a low pressure to form a deposited film on a substrate, an internal pressure of 50 mT
At a vacuum degree of orr or less, a microwave energy smaller than the microwave energy required for 100% decomposition of the source gas is applied to the source gas, and at the same time, an rf energy larger than the microwave energy to be applied is applied to the source gas. A mesh made of a conductive metal is interposed between the substrate and the space in which the source gas is mainly decomposed by the microwave energy to be caused to act, and the mesh is kept at 100 ° C. when the deposited film is formed.
A method of forming a deposited film by a microwave plasma CVD method, which comprises heating and holding at the above temperature.

(3) In a microwave plasma CVD method in which a raw material gas for forming a deposited film is decomposed by microwave energy under a low pressure to form a deposited film on a substrate, an internal pressure of 50 mT
At a vacuum degree of orr or less, a microwave energy smaller than the microwave energy required for 100% decomposition of the source gas is applied to the source gas, and at the same time, an rf energy larger than the microwave energy to be applied is applied to the source gas. A mesh made of a conductive metal is interposed between the substrate and the space in which the source gas is mainly decomposed by the microwave energy to be caused to act, and an rf bias voltage is applied to the mesh. A characteristic method for forming a deposited film by a microwave plasma CVD method.

The present invention will be described in detail below.

[0026]

The details of the deposition mechanism in the method of forming a deposited film according to the present invention described in (1) to (3) above are not completely clear yet, but it is considered as follows.

By applying a microwave energy smaller than the microwave energy required for 100% decomposition of the source gas to the source gas, a large rf energy is applied to the source gas at the same time as the microwave energy to form a deposited film. It is believed that the active species suitable for forming can be selected. Furthermore, when the internal pressure in the deposition chamber when decomposing the source gas is 50 mTorr or less, it is considered that the gas phase reaction is suppressed as much as possible because the mean free path of active species suitable for forming a good quality deposited film is sufficiently long. . It is also considered that when the internal pressure in the deposition chamber is 50 mTorr or less, the rf energy has almost no effect on the decomposition of the source gas, and controls the potential between the plasma and the deposition chamber inner wall including the mesh. .

That is, when only microwave energy is input, the potential difference between the plasma and the inner wall surface of the deposition chamber is small, but when the rf energy is input at the same time as the microwave energy, the potential difference between the plasma and the inner wall surface of the deposition chamber ( In general, the plasma side becomes positive with respect to the wall surface of the deposition chamber). Since the plasma potential is positively high with respect to the inner wall surface of the deposition chamber, positive ions accelerated by the plasma potential among the active species decomposed by microwave energy mainly pass through the mesh and collide with each other on the substrate. It is considered that by giving the surface energy, the relaxation reaction on the surface of the deposited film is promoted and a good quality deposited film can be obtained. This effect is particularly remarkable when the deposition rate is 1 nm / sec or more.

Further, since rf has a high frequency unlike DC, the potential difference between the plasma and the inner wall surface of the deposition chamber is determined by the distribution of ionized ions and electrons. That is, the potential difference between the mesh and the plasma is determined by the synergy of ions and electrons. Therefore, in the microwave plasma CVD method in which the rf energy is superimposed, it has been found that abnormal discharge is unlikely to occur in the deposition chamber.

Further, even if an abnormal discharge should occur,
By interposing a mesh made of a conductive metal between the plasma and the substrate, it is possible to reduce the adverse effect of abnormal discharge on the substrate.

At this time, the presence of the mesh can effectively reduce damage to the deposited film caused by unwanted ions and electrons reaching the substrate.

Further, by applying an appropriate DC bias voltage to the mesh, it is possible to correct and enhance the effect of the electric field as described above, and by applying an appropriate acceleration to the ions passing through the mesh. It is possible to optimize the energy applied to the surface of the deposited film, and at the same time, it is possible to effectively reduce the impact of unnecessary ions and electrons that adversely affect the deposited film.

Further, by heating and holding the mesh at a temperature of 100 ° C. or higher during the formation of the deposited film, the lifetime of active species having energy that effectively contributes to structural relaxation in the film during the formation process of the deposited film. It becomes possible to extend and supply the active species in abundance to the surface of the deposited film. As a result, structural relaxation in the deposited film is promoted during the formation process of the deposited film, disturbance of the network in the deposited film is reduced, and electrical characteristics and reliability of the electronic device to be deposited can be improved.

By applying an appropriate rf bias voltage to the mesh, the electric field strength determined by the synergy of ionized ions and electrons can be obtained between the mesh and the substrate. This electric field provides effective acceleration to ions and electrons, effectively selecting active species having energy that contributes to structural relaxation in the deposited film formation process, and at the same time, unnecessary electrons that cause harmful damage to the deposited film. By effectively reducing the influence of ions, it is possible to reduce the disorder of the network in the deposited film.
Further, it has been found that when an rf bias voltage is applied to the mesh, abnormal discharge due to an electric field between the mesh and the substrate is unlikely to occur.

The deposited film preferably manufactured by the above-described deposited film forming method of the present invention and the deposited film manufacturing apparatus using the method is a non-single crystal semiconductor film, particularly an amorphous hydrogenated silicon film (a-Si: H). Abbreviated), amorphous hydrogenated silicon halide film (abbreviated as a-Si: HX), amorphous hydrogenated silicon germanium film (abbreviated as a-SiGe: H) amorphous hydrogenated silicon halide germanium film (abbreviated) a-SiG
e: abbreviated as HX), an amorphous hydrogenated silicon carbide film (a-
SiC: H) and an amorphous hydrogenated halogenated silicon carbide film (abbreviated as a-SiC: HX) (all or part of the hydrogen may be replaced with deuterium) and the like. .

The deposited film forming method of the present invention and the deposited film forming apparatus for carrying out the method will be described below in more detail with reference to the drawings.

First, the method (1) of the present invention will be described.

FIG. 1 is a schematic diagram for explaining an example of a manufacturing apparatus system suitable for applying the deposited film forming method of the present invention. FIG. 2 is a schematic explanatory view of an example of a photovoltaic element formed by the deposited film forming method of the present invention. Figure 3
FIG. 4 is a schematic explanatory diagram of a DC magnetron sputtering apparatus for depositing a light reflection layer and a light reflection enhancement layer on a substrate when forming a photovoltaic element. FIG. 4 is a schematic explanatory view of a resistance heating vacuum vapor deposition apparatus for depositing a transparent electrode and a collector electrode of a photovoltaic element.

The deposited film forming method of the present invention will be described based on the manufacturing apparatus system schematically shown in FIG. The manufacturing apparatus system shown in FIG. 1 includes a manufacturing apparatus 100 and a source gas supply device 1020.

The production apparatus 100 includes a deposition chamber 101, a dielectric window 102 for introducing microwaves, a gas introduction tube 103, a substrate 104, a heater 105, a vacuum gauge 106, a conductance valve 107, an auxiliary valve 108, and a leak valve 1.
09, a waveguide section 110 for introducing microwaves, a bias power source 111 for applying a bias voltage to plasma, a bias rod 112, a mesh 113, a DC bias power source 114 for applying a DC bias voltage to the mesh, and the like. ing.

As a material forming the mesh 113 that is preferably used in the deposited film forming method of the present invention, Ni,
Stainless steel, Al, Cr, Mo, Au, Nb, Ta,
Examples include simple metals such as V, Ti, Pt, Pb, and Sn, and alloys thereof. Particularly, Al is preferable because it is easy to process and has high electric conductivity. In addition, stainless steel, Ni, etc. are preferable because they have high durability against plasma. The material is appropriately selected and used from these materials to form a desired deposited film.

The shape of the mesh 113 preferably used in the deposited film forming method of the present invention is a knitted material of a linear material, or a material of a plate material which is expanded by making fine cuts (expanded metal). ), Various materials such as punching metal can be used, but it is preferable that the maximum diameter of the mesh opening is 10 mm or less in order to secure the selectivity of active species and the stability of plasma, and the opening ratio is 1
It is preferably 0% or more from the viewpoint of increasing the utilization factor of the source gas and reducing the pressure unevenness inside the film forming chamber. The distance between the mesh 113 and the substrate 104 is appropriately determined according to various conditions such as the aperture ratio of the mesh 113, the internal pressure, and the DC bias voltage. Usually, the thickness and characteristics of the deposited film are uneven within a range of 2 to 30 mm. Is set and the characteristics are optimized.

In order to apply a DC bias voltage to the mesh 113, the mesh is electrically insulated from the substrate 104, the deposition chamber 101, etc., and is connected to the mesh DC bias power source 114. There is.

The mesh 113 is at least the substrate 1.
It is installed so as to cover the surface of 04, and may be installed so as to divide the inside of the deposition chamber 101 into two as shown in FIG. 1, or the substrate 104 and the heater 10.
It may be installed so as to surround 5.

Further, it is preferable to control the formation of the deposited film on the substrate 104 by installing a shutter 115 that can be operated from the outside of the deposition chamber 101 near the substrate 104. It is preferable to install the shutter 115 between the mesh 113 and the substrate 104 because the opening and closing of the shutter 115 has less influence on plasma.

Further, in FIG. 1, the substrate 104 and the mesh 1
Although 13 is installed perpendicularly to the microwave introduction direction, the present invention is not limited to this, and it is also possible to install it in parallel or obliquely.

Further, it is preferable that the mesh 113 can be substantially removed by an operation from the outside while keeping the vacuum in the deposition chamber 101 according to a desired deposition film forming condition. Similarly, it is more preferable that the mesh can be exchanged for another type and shape by an external operation. Further, it is preferable that the mesh 113 can be moved continuously or intermittently (for example, a device including a delivery roll and a winding roll) because the influence of a deposited film attached to the mesh can be reduced.

The raw material gas supply device 1020 includes the introduction valves 1041 to 1046 for introducing the raw material gas, the mass flow controllers 1021 to 1026, the primary valves 1031 to 1036 of the mass flow controller, and the pressure regulator 10.
61 to 1066, cylinder valves 1051 to 1056,
It is composed of raw material gas cylinders 1071 to 1076 and the like.

An example of the film forming procedure by the above film forming system will be described below.

First, a substrate 104 for forming a deposited film is mounted in the deposition chamber 101 shown in FIG. 1 and the deposition chamber is evacuated to a level of 10.sup.- ⁵ Torr or lower. A turbo molecular pump is suitable for this exhaust, but an oil diffusion pump may be used. However, when an oil diffusion pump is used, gases such as H ₂ , He, Ar, Ne, Kr, and Xe are introduced into the deposition chamber when the internal pressure of the deposition chamber 101 becomes 10 ⁻⁴ or less so that the oil does not diffuse back into the deposition chamber. Is preferably introduced into After sufficiently exhausting the inside of the deposition chamber, H ₂ , He, Ar, Ne, Kr, X
A gas such as e is introduced into the deposition chamber so that the pressure in the deposition chamber is almost the same as when the source gas for forming the deposited film is flowed. The pressure inside the deposition chamber is 0.5 to 50 mTorr.
Is the optimum range. When the internal pressure in the deposition chamber has stabilized, the substrate heating heater 105 is turned on to turn the substrate 100-
Heat to 500 ° C. When the temperature of the substrate stabilizes at a predetermined temperature, the gases such as H ₂ , He, Ar, Ne, Kr, and Xe are stopped, and a predetermined amount of the raw material gas for forming the deposited film is introduced into the deposition chamber from the gas cylinder through the mass flow controller. To do.
The supply amount of the source gas for forming the deposited film introduced into the deposition chamber is appropriately determined depending on the volume of the deposition chamber, desired characteristics of the deposited film, and the like. The pressure in the deposition chamber when the source gas for forming the deposited film is introduced into the deposition chamber is a very important factor in the method of the present invention, and the optimum internal pressure in the deposition chamber is 0.5 to 50 mTorr.

In the method of the present invention, the microwave energy input into the deposition chamber for forming the deposited film is an important factor. The magnitude of the microwave energy is appropriately determined depending on the flow rate of the source gas introduced into the deposition chamber, the volume of the deposition chamber, the shape of the deposition chamber, the position of the substrate, and other conditions. The energy is smaller than the microwave energy required for 100% decomposition, and the preferable range is 0.02 to 1 W / cm.
^{Is 3} . As a preferable frequency range of microwave energy, 0.5 to 10 GHz can be mentioned.
A frequency near 2.45 GHz is particularly suitable. Further, in order to form a deposited film with reproducibility by the deposited film forming method of the present invention and to form a deposited film on a long substrate continuously conveyed for several hours to several tens of hours, microwave energy is required. The frequency stability of is very important. It is preferable that the frequency variation is within ± 2%. Further, the ripple of the microwave is preferably within ± 2%.

It should be noted that the fact that the input microwave energy is smaller than the microwave energy required for 100% decomposition of the raw material gas is obtained by conducting an experiment as described below in advance. I can confirm.

The conditions other than the microwave energy are set to be the same as in the actual formation of the deposited film, and the deposited film single film is formed while changing only the microwave energy value to be input. Examine the relationship between wave energy values. Then, when the source gas is decomposed 100% by the microwave energy and contributes to the formation of the deposited film, the deposition rate has no or small dependence on the microwave energy value (source gas flow rate-controlled state).
However, when the value is smaller than the microwave energy required for 100% decomposition of the source gas, it can be understood that the dependence of the deposition rate on the microwave energy is large (microwave energy rate-determining state). That is, in the deposited film forming method of the present invention, the deposited film is formed in the microwave energy rate-determining state, which can be confirmed by examining the relationship between the microwave energy and the deposition rate.

Further, in the deposited film forming method of the present invention, r is introduced into the deposition chamber at the same time as the microwave energy.
The f energy is a very important factor in combination with the microwave energy, and a preferable range of the rf energy is 0.04 to 2 W / cm ³ , and a bias rod installed in the plasma generation space in the deposition chamber. Is applied to the plasma through.

A preferable frequency range of the rf energy is 1 to 100 MHz. Also r
The fluctuation of the frequency of f is preferably within ± 2% and the waveform is smooth.

In addition to the rf energy, a DC bias voltage may be applied to the bias rod 112 in an overlapping manner. The polarity of the DC bias voltage depends on the deposition chamber 101.
It is preferable to apply a voltage so that the bias rod 112 becomes positive. The preferable range of the DC bias voltage is 300 V or less.

When a bias voltage is applied to the bias rod 112 before the generation of plasma by the introduction of microwaves, abnormal discharge is rarely found in an unstable state at the beginning of plasma generation, which is a characteristic of the deposited film. It is preferable that the bias voltage be applied to the bias rod 112 after the plasma is stabilized, because it may adversely affect the temperature.

The microwave energy is introduced into the deposition chamber from the waveguide 110 through the dielectric window 102, and the deposition chamber 1 is
After the source gas introduced into 01 is decomposed to generate plasma and the plasma is stabilized, rf energy is introduced from the bias power source 111 into the deposition chamber via the bias rod 112. Then, a DC bias voltage is applied to the mesh 113. The value of the DC bias voltage applied to the mesh 113 is appropriately determined by parameters such as the structure and size in the deposition chamber 101 and the desired characteristics of the deposited film, but is preferably 300 V or less.

When a DC bias voltage is applied to the mesh 113 before the generation of plasma by the introduction of microwaves, abnormal discharge is rarely found in an unstable state at the beginning of plasma generation, which is a characteristic of the deposited film. Therefore, it is preferable that the DC bias voltage be applied to the mesh 113 after the plasma is stabilized.

With the gas flow rate, deposition chamber pressure, plasma, bias current, etc. being stable, the shutter 113 is opened to form a deposition film of a desired thickness on the substrate 104 for a desired time. When the thickness of the deposited film reaches a desired value, the shutter 113 is closed, and the mesh D
C bias voltage application, microwave energy, rf energy, introduction of source gas was stopped, the inside of the deposition chamber 101 was evacuated, and the inside of the deposition chamber 101 was sufficiently filled with gas such as N ₂ , He, Ar, Ne, Kr, and Xe. After purging, the substrate 104 on which the non-single crystal semiconductor film is deposited is taken out from the deposition chamber 101.

Next, the method (2) of the present invention will be described.

FIG. 5 is a schematic diagram for explaining an example of a manufacturing apparatus system suitable for applying the deposited film forming method of the present invention. 2A and 2B are schematic explanatory views of examples of photovoltaic elements formed by the deposited film forming method of the present invention.

The deposited film forming method of the present invention will be described based on the manufacturing apparatus system schematically shown in FIG. The manufacturing apparatus system shown in FIG. 5 basically complies with the manufacturing apparatus system of the method of the present invention described in (1) above, and includes a manufacturing apparatus 100 and a source gas supply device 1020.

The production apparatus 100 includes a deposition chamber 101, a dielectric window 102 for introducing microwaves, a gas introduction tube 103, a substrate 104, a heater 105, a vacuum gauge 106, a conductance valve 107, an auxiliary valve 108, and a leak valve 1.
09, a waveguide section 110 for introducing microwaves, a bias power source 111 for applying a bias voltage to plasma, a bias rod 112, a mesh 113, a temperature controller 116 for adjusting the temperature of the mesh, and the like.

The basic operation and apparatus in this method of the present invention are the same as those in the method of the present invention described in (1) above, but the deposited film is formed while heating and holding the mesh 113 at 100 ° C. or higher. It is characterized by that.

As a method of adjusting the temperature of the mesh 113, a filament made of a refractory metal such as tungsten is placed in contact with the mesh or in the vicinity of the mesh, and an AC or DC current is passed through the filament to generate heat. Then, the mesh 113 is heated, and at the same time, the temperature of the mesh 113 is measured using a temperature measuring element such as a thermocouple,
A suitable method is to control this.

As another method for adjusting the temperature of the mesh 113, a halogen lamp or the like is installed near the mesh and the mesh 113 is irradiated with light.
A method in which 3 is heated and at the same time the temperature of the mesh 113 is measured using a temperature measuring element such as a thermocouple and the temperature is controlled can also be mentioned as a suitable method.

As another method of adjusting the temperature of the mesh 113, an electric current of AC or DC is applied to the mesh 113 to generate heat by the electric resistance of the mesh itself, and at the same time, the temperature of the mesh 1 is measured by using a temperature measuring element such as a thermocouple.
A method of measuring the temperature of 13 and controlling it can also be mentioned as a suitable method.

Further, in order to adjust the temperature of the mesh 113, it is necessary to provide a cooling means such as a water cooling mechanism and a Peltier element in addition to the above heating means.
It is effective and preferable for finely adjusting the temperature of.

Also in the method of the present invention, a bias voltage may be applied to the mesh 113 as in the case of (1). In that case, the mesh needs to be electrically insulated from the substrate 104, the deposition chamber 101 and the like, and a bias power source needs to be connected to the mesh. Further, when the mesh has the same potential as that of the deposition chamber 101, a conductive member for electrically connecting the mesh to the wall surface of the deposition chamber may be provided between the mesh and the deposition chamber 101. Good.

An example of the film forming procedure based on the manufacturing apparatus system shown in FIG. 5 will be shown below, but it goes without saying that the film forming procedure is not limited to this.

First, a substrate 104 for forming a deposited film is attached in the deposition chamber 101 shown in FIG. 5, and the deposition chamber is evacuated to a level of 10.sup.- ⁵ Torr or lower. A turbo molecular pump is suitable for this exhaust, but an oil diffusion pump may be used. However, when an oil diffusion pump is used, gases such as H ₂ , He, Ar, Ne, Kr, and Xe are introduced into the deposition chamber when the internal pressure of the deposition chamber 101 becomes 10 ⁻⁴ or less so that the oil does not diffuse back into the deposition chamber. Is preferably introduced into After sufficiently exhausting the inside of the deposition chamber, H ₂ , He, Ar, Ne, Kr, X
A gas such as e is introduced into the deposition chamber so that the pressure in the deposition chamber is almost the same as when the source gas for forming the deposited film is flowed. The pressure inside the deposition chamber is 0.5 to 50 mTorr.
Is the optimum range. When the internal pressure in the deposition chamber has stabilized, the substrate heating heater 105 is turned on to turn the substrate 100-
Heat to 500 ° C. When the temperature of the substrate stabilizes at a predetermined temperature, the gases such as H ₂ , He, Ar, Ne, Kr, and Xe are stopped, and a predetermined amount of the raw material gas for forming the deposited film is introduced into the deposition chamber from the gas cylinder through the mass flow controller. To do.
The supply amount of the source gas for forming the deposited film introduced into the deposition chamber is appropriately determined depending on the volume of the deposition chamber, desired characteristics of the deposited film, and the like. The pressure in the deposition chamber when the source gas for forming the deposited film is introduced into the deposition chamber is a very important factor in the deposition film forming method of the present invention, and the optimum internal pressure in the deposition chamber is 0.5 to 50 mTorr. Is.

Further, the temperature of the mesh 113 is set to a predetermined temperature of 100 ° C. or higher by operating the temperature controller 114 for the mesh 113.

In the deposited film forming method of the present invention, the microwave energy input into the deposition chamber for forming the deposited film is an important factor.

With the gas flow rate, deposition chamber pressure, plasma, bias current, etc. being stable, the shutter 113 is opened to form a deposition film having a desired film thickness on the substrate 104 for a desired time. When the thickness of the deposited film reaches a desired value, the shutter 113 is closed, application of bias voltage to the bias rod 112, introduction of microwave energy and source gas is stopped, and the inside of the deposited film 101 is evacuated. ₂ , He,
The substrate 10 on which the non-single-crystal semiconductor film is deposited after the inside of the deposition chamber 101 is sufficiently purged with a gas such as Ar, Ne, Kr, or Xe.
4 is taken out from the deposition chamber 101.

Next, the method (3) of the present invention will be described.

FIG. 8 is a schematic diagram for explaining an example of a manufacturing apparatus system suitable for applying the deposited film forming method of the present invention.

The deposited film forming method of the present invention will be described based on the manufacturing apparatus system schematically shown in FIG. The manufacturing apparatus system shown in FIG. 8 includes a manufacturing apparatus 100 and a source gas supply device 1020.

The manufacturing apparatus 100 includes a deposition chamber 101, a dielectric window 102 for introducing microwaves, a gas introduction tube 103, a substrate 104, a heater 105, a vacuum gauge 106, a conductance valve 107, an auxiliary valve 108, and a leak valve 1.
09, a waveguide section 110 for introducing microwaves, a bias power source 111 for applying a bias voltage to plasma, a bias rod 112, a mesh 113, an rf bias power source 117 for applying an rf bias voltage to the mesh, and the like. ing.

Also in this method, the basic operation and apparatus are the same as in the case of (1) already described, but the feature is that an rf bias voltage is applied to the mesh 113.

As a method of applying the rf voltage, microwave energy is introduced into the deposition chamber from the waveguide 110 through the dielectric window 102 to decompose the source gas introduced into the deposition chamber 101 to generate plasma. After the plasma is stabilized, rf energy is introduced from the bias power source 111 into the deposition chamber via the bias rod 112. Then, an rf bias voltage is applied to the mesh 113. The frequency of the rf bias voltage applied to the mesh 113 depends on parameters such as the structure and size in the deposition chamber 101.
Further, although it is appropriately determined depending on the desired characteristics of the deposited film, it preferably has a frequency of 1 to 100 MHz. The voltage value of the bias voltage applied to the mesh 113 is appropriately determined by parameters such as the structure and size in the deposition chamber 101 and the desired characteristics of the deposited film, but is preferably peak-to-peak. Is 1 kV or less. Also, the frequency fluctuation is ± 2%
It is preferable that the waveform is smooth within the range.

When the rf bias voltage is applied to the mesh 113 before the generation of plasma by the introduction of microwaves, abnormal discharge is rarely seen in an unstable state at the initial stage of plasma generation, which is the characteristic of the deposited film. It is preferable that the rf bias voltage is applied to the mesh 113 after the plasma is stabilized, since it may adversely affect the above.

With the gas flow rate, deposition chamber pressure, plasma, bias current, etc. being stable, the shutter 113 is opened to form a deposition film having a desired film thickness on the substrate 104 for a desired time. When the thickness of the deposited film reaches a desired value, the shutter 113 is closed and the mesh 113 is r
The application of the f-bias voltage, the microwave energy, the rf energy, and the introduction of the source gas are stopped, the inside of the deposition chamber 101 is evacuated, and the inside of the deposition chamber 101 is sufficiently filled with a gas such as N ₂ , He, Ar, Ne, Kr, or Xe. After purging, the substrate 104 on which the non-single crystal semiconductor film is deposited is taken out from the deposition chamber 101.

Here, the source gas suitable for the present invention will be described.

[0085] As a raw material gas for silicon deposition, containing silicon atoms, is preferable gasifiable compounds, for example, SiH4, SiH 6, SiF4, SiFH3, Si
F2H2, SiF3H, Si3H8, SiD4, SiH
D3, SiH2D2, SiHD, SiFD ₃ , SiF ₂
D ₂ , SiD ₃ H, Si ₂ H ₆ , Si ₂ D ₆ , Si ₂ D
₃ H _{3 and the} like can be mentioned.

As a source gas for depositing germanium,
A compound containing a germanium atom and capable of being gasified is preferable, and examples thereof include GeH ₄ , GeD ₄ , GeF ₄ , and GeFH.
₃ , GeF ₂ H ₂ , GeF ₃ H, GeHD ₃ , GeH ₂
D _2, GeH ₃ D, mention may be made of _{Ge 2 H 6, Ge 2 D} 6 , and the like.

As the source gas for depositing carbon atoms, a compound containing carbon atoms and capable of being gasified is preferable.
H ₄ , CD ₄ , C _n H _{2n + 2} (n is an integer), C _n H _2n (n
Is an integer), C ₂ H ₂ , C ₆ H _{6 and the} like.

Further, as the substance introduced into the non-single crystal semiconductor layer for controlling the conduction type of the non-single crystal semiconductor layer, there can be mentioned Group III atoms and Group V atoms of the periodic table.

Materials that are effectively used as a starting material for introducing a Group III atom include B ₂ H ₆ , B ₄ H ₁₀ , B ₅ H ₉ , B ₅ H ₁₁ and B ₆ for introducing a boron atom. H ₁₀ ,
Borohydrides such as B ₆ H ₁₂ and B ₆ H ₁₄ , and BF ₃ ,
Examples thereof include boron halides such as BCl ₃ . In addition to this, AlCl ₃ , GaCl ₃ , InCl ₃ ,
TlCl _{3 and the} like can also be mentioned.

Effectively used as a starting material for introducing a Group V atom is PH ₃ , P ₂ H for introducing a phosphorus atom.
₄ hydrogen, such as phosphorus, and _{PH 4 I, PF 3, PF} 5, P
Examples thereof include phosphorus halides such as Cl ₃ , PCl ₅ , PBr ₃ , PBr ₅ , and PI ₃ . In addition, AsH ₃ ,
_{AsF 3, AsCl 3, AsBr 3} , AsF 5, SbH
₃ , SbF ₅ , SbF ₅ , SbCl ₃ , SbCl ₅ , B
iH _3, BiCl _3, BiBr _3, and the like can also be mentioned.

In order to control the conduction type of the amorphous crystalline semiconductor layer to be almost i-type, the introduction amount of the group III atom and the group V atom of the periodic table introduced into the layer is preferably 1000 ppm or less. You can Further, in order to control the conduction type to be almost i-type, an atom of group III and an atom of group V of the periodic table may be added so as to be simultaneously compensated.

The introduced amount of the group III atom of the periodic table and the group V atom of the periodic table introduced for controlling the conductivity type of the non-single-crystal semiconductor layer to p-type or n-type is 100 ppm to 10%.
Can be mentioned as a preferable range.

Further, the above-mentioned gasifiable compound is added to N ₂ , D
The gas may be appropriately diluted with a gas such as ₂ , He, Ne, Ar, Xe, and Kr and introduced into the deposition chamber. In particular, N ₂ , D ₂ , and H are the most suitable gases for diluting the above-mentioned gasifiable compounds.
e can be mentioned.

Next, a preferred application example of the present invention will be described.

As described above, the deposited film forming method of the present invention is
The method is suitable for forming semiconductor layers used in various electronic devices such as photovoltaic elements, sensors, thin film transistors, and electrophotographic image forming members. Hereinafter, the case where the deposited film forming method of the present invention is applied to the production of a photovoltaic element will be described, but it goes without saying that the present invention is not limited to this and can be applied to other electronic devices. .

<Application to Photovoltaic Element> FIGS. 2A and 2B are schematic explanatory views of a photovoltaic element used for a solar cell, a sensor, or the like. Figure 2 (a)
In photovoltaic element 200, conductive substrate 201, light reflection layer 202, light reflection increasing layer 203, n-type (p-type) conductivity type layer 204, i-type layer 205, p-type (n-type) conductivity type layer 20.
6, a transparent electrode 207 and a collector electrode 208. Then, the light is emitted from the transparent electrode 207 side.

Further, the first conductivity type layer, the i-type layer and the second conductivity type layer may be taken as one unit to form a double cell or triple cell structure in which 2 units or 3 units of these units are stacked. The structure of the double cell is schematically shown in FIG. In FIG. 2B, the photovoltaic element 210
Is the conductive substrate 211, the light reflection layer 212, the light reflection increasing layer 213, the first n-type (p-type) conductivity type layer 214, and the first i.
Type layer 215, first p-type (n-type) conductivity type layer 216, second
N-type (p-type) conductivity type layer 217, second i-type layer 218,
It is composed of a second p-type (n-type) conductivity type layer 219, a transparent electrode 220, and a collector electrode 221. Then, the light is emitted from the transparent electrode 220 side.

On the other hand, a member having a substantially light-transmitting property is used for the substrate, and a transparent electrode, each semiconductor layer, and a light-reflecting metal electrode are provided in this order on the substrate, and light is incident from the transparent substrate side. The deposited film forming method of the present invention can be applied to a photovoltaic element.

Further, it is preferable to texture at least one of the conductive substrate, the light reflection layer, the light reflection increasing layer and the transparent electrode because the photocurrent of the photovoltaic element can be increased.

The structure of the photovoltaic element suitable for the present invention will be described below. However, it is needless to say that the following description is one mode of the present invention and the present invention is not limited to this and can be applied to a photovoltaic element having another configuration.

<Structure of Photovoltaic Device> Conductive Substrate The conductive substrate may be a conductive material, and a support is formed of an electrically insulating material or a conductive material, and a conductive treatment is performed thereon. It may be one. Examples of the conductive material preferably used in the present invention include Ni, stainless steel, Al, Cr, Mo, Au, Nb, Ta, V, and Ti.
Examples include simple metals such as Pt, Pb, and Sn or alloys thereof.

The electrically insulating material preferably used in the present invention is a film or sheet of synthetic resin such as polyester, polyethylene, polycarbonate, cellulose acetate, polypropylene, polyvinyl chloride, polyvinylidene chloride, polystyrene and polyamide. , Glass, ceramics, paper, and the like. It is preferable that at least one surface of these electrically insulating materials is subjected to an electric conduction treatment, and a photovoltaic layer is provided on the surface side subjected to the electric conduction treatment.

For example, in the case of glass, N
iCr, Al, Cr, Mo, Ir, Nb, Ta, V, T
i, Pt, Pb, In ₂ O ₃ , SnO ₂ , ITO (In
₂ O ₃ + SnO ₂ ) or the like to provide conductivity, or synthetic resin film such as polyester film, NiCr, Al, Ag, P
b, Zn, Ni, Au, Cr, Mo, Ir, Nb, T
A metal thin film of a, V, Tl, Pt or the like is provided on the surface by vacuum vapor deposition, electron beam vapor deposition, sputtering or the like, or the surface is laminated with the metal to impart conductivity to the surface. The shape of the support may be a sheet having a smooth surface or an uneven surface. The thickness is appropriately determined so that a desired photovoltaic can be formed, but when flexibility as a photovoltaic element is required, it is possible within a range in which the function as a support is sufficiently exhibited. It can be made as thin as possible. However, in view of film formation and handling of the support, mechanical strength and the like, the thickness is usually 10 μm or more. Light-Reflecting Layer For the light-reflecting layer, a metal such as Ag, Al, Cu, or AlSi having a high reflectance from visible light to near infrared light is suitable. As a method of forming the light reflecting layer made of these metals,
The resistance heating vacuum vapor deposition method, the electron beam vacuum vapor deposition method, the co-evaporation method, the sputtering method and the like can be mentioned as suitable ones. As a layer thickness of these metals as the light reflecting layer, a suitable layer thickness is 10 nm to 5000 nm. As a method for texturing the surface of the light reflecting layer, there are many known methods such as a sand blast method and a chemical etching method. The method of spontaneously texturing by making the metal layer relatively thick is a method that can be performed easily and with good reproducibility. Reflection-increasing layer As the reflection-increasing layer, ZnO, SnO ₂ , In ₂ O ₃ , I
TO, TiO ₂ , CdO, Cd ₂ SnO ₄ , Bi
₂ O ₃ , MoO ₃ , Na _x WO ₃ , etc. can be mentioned as the optimum ones.

Suitable methods for depositing the reflection-increasing layer include vacuum evaporation method, sputtering method, CVD method, spray method, spin-on method, dip method and the like.

The optimum value of the thickness of the reflection increasing layer varies depending on the refractive index of the material of the reflection increasing layer and the like, but a preferable range is 50 nm to 10 μm. P-type layer or n-type layer (first and second conductivity type layers) The p-type layer or n-type layer is an important layer that influences the characteristics of the photovoltaic element.

As an amorphous material (denoted as a-) (microcrystalline material (denoted as μc-)) of the p-type layer or n-type layer, it goes without saying that it falls into the category of amorphous materials. , A-Si: H, a-Si: HX (X is a halogen atom such as F or Cl), a-SiC: H, a-SiC: HX,
a-SiGe: H, a-SiGeC: H, a-SiO:
H, a-SiN: H, a-SiON: HX, a-SiO
CN: HX, μc-Si: H, μc-SiC: H, μc
-Si: HX, μc-SiC: HX, μc-SiGe:
H, μc-SiO: H, μc-SiGeC: H, μc-
SiN: H, μc-SiON: HX, μc-SiOC
N: HX, etc., such as a p-type valence electron control agent (group III atom B, Al, Ga, In, Tl of the periodic table) or an n-type valence electron control agent (group V atom, P, As a material containing a high concentration of As, Sb, Bi), a polycrystalline material (pol
(displayed as y-), for example, poly-Si:
H, poly-Si: HX, poly-SiC: H, p
poly-SiC: HX, poly-SiGe: H, po
ly-Si, poly-SiC, poly-SiGe,
And a p-type valence electron control agent (group III atom B of the periodic table,
Examples of the material include Al, Ga, In, Tl) and n-type valence electron control agents (group V atom of the periodic table, P, As, Sb, Bi) added in high concentration.

Particularly, for the p-type layer or the n-type layer on the light incident side, a crystalline semiconductor layer with little light absorption or an amorphous semiconductor layer with a wide band gap is suitable.

The amount of the group III atom of the periodic table added to the p-type layer and the amount of the group V atom of the periodic table added to the n-type layer are 0.1 to 0.1%.
50% can be mentioned as the optimum amount.

Hydrogen atoms (H, D) or halogen atoms contained in the p-type layer or the n-type layer serve to compensate dangling bonds in the p-type layer or the n-type layer, and It improves the doping efficiency of the layer. The optimum amount of hydrogen atoms or halogen atoms added to the p-type layer or the n-type layer is 0.1 to 40%. Especially when the p-type layer or the n-type layer is crystalline, the hydrogen atom or halogen atom is 0.1
-8% can be mentioned as the optimum amount. In addition, hydrogen atoms or / on the interface sides of the p-type layer / i-type layer and the n-type layer / i-type layer
And those in which the content of halogen atoms is large are listed as a preferable distribution form, and the content of hydrogen atoms and / or halogen atoms in the vicinity of the interface is 1.1 to 2 times the content in the bulk. The range can be mentioned as a preferable range. Thus, by increasing the content of hydrogen atoms or halogen atoms in the vicinity of each interface of the p-type layer / i-type layer and the n-type layer / i-type layer, the defect level and stress near the interface can be reduced. Therefore, the photovoltaic power and photocurrent of the photovoltaic device of the present invention can be increased.

Regarding the electrical characteristics of the p-type layer and the n-type layer of the photovoltaic element, the activation energy is preferably 0.2 eV or less, and most preferably 0.1 eV or less. The specific resistance is preferably 100 Ωcm or less, and most preferably 1 Ωcm or less. Furthermore, the layer thickness of the p-type layer and the n-type layer is 1 to 5
0 nm is preferable and 3 to 10 nm is optimum.

As the source gas suitable for depositing the p-type layer or the n-type layer of the photovoltaic element, a gasifiable compound containing a silicon atom, a gasifiable compound containing a germanium atom, or a carbon atom was contained. Examples thereof include compounds that can be gasified or mixed gas of the compounds.

Specific examples of the gasifiable compounds containing silicon atoms include SiH ₄ , SiH ₆ , SiF ₄ , and S.
iFH ₃ , SiF ₂ H ₂ , SiF ₃ H, Si ₃ H ₈ , S
iD ₄ , SiHD ₃ , SiH ₂ D ₂ , SiH ₃ D, Si
FD ₃ , SiF ₂ D ₂ , SiD ₃ H, Si ₂ D ₃ H ₃ ,
Etc. can be mentioned.

Specifically, as the gasifiable compound containing a germanium atom, GeH ₄ , GeD ₄ , GeF ₄ ,
GeFH ₃ , GeF ₂ H ₂ , GeF ₃ H, GeHD ₃ ,
_{GeH 2 D 2, GeH 3 D} , mention may be made of _{Ge 2 H 6, Ge 2 D} 6 , and the like.

Specific examples of the gasifiable compound containing a carbon atom include CH ₄ , CD ₄ , C _n H _{2n + 2} (n is an integer), C _n H _2n (n is an integer), C ₂ H ₂ and C. ₆ H ₆ , CO
₂ , CO and the like can be mentioned.

Examples of the substance introduced into the p-type layer or the n-type layer for controlling the valence electrons include Group III atoms and Group V atoms of the periodic table.

As the starting material effectively used for introducing a Group III atom, specifically, for introducing a boron atom, B ₂ H ₆ , B ₄ H ₁₀ , B ₅ H ₉ , B can be used.
_{5 H 11, B 6 H 10} , B 6 H 12, B 6 H 14 , etc. borohydride, BF _3, BCl _3, and halogenated boron such as equal. In addition to this, AlCl ₃ , GaCl ₃ ,
InCl ₃ , TlCl _{3 and the} like can also be mentioned. B ₂ H ₆ and BF ₃ are particularly suitable.

What is effectively used as a starting material for introducing a group V atom is specifically PH for introducing a phosphorus atom.
₃ , Phosphorus hydride such as P ₂ H ₄ , PH ₄ I, PF ₃ , P
F ₅ , PCl ₃ , PCl ₅ , PBr ₃ , PBr ₅ , PI
Examples thereof include phosphorus halides such as ₃ . Besides this A
sH ₃ , AsF ₃ , AsCl ₃ , AsBr ₃ , As
F ₅ , SbH ₃ , SbF ₃ , SbF ₅ , SbCl ₃ , S
Other examples include bCl ₅ , BiH ₃ , BiCl ₃ , BiBr _{3 and the} like. Particularly, PH ₃ and PF ₃ are suitable.

Suitable methods for depositing a p-type layer or an n-type layer for a photovoltaic element are an rf plasma CVD method and a microwave plasma CVD method.

When depositing by the rf plasma CVD method, the capacitive coupling type rf plasma CVD method is suitable.

When the p-type layer or the n-type layer is deposited by the rf plasma CVD method, the substrate temperature in the deposition chamber is 100 to 3
50 ° C., internal pressure 0.1 to 10 Torr, rf energy 0.05 to 1.0 W / cm ² , deposition rate 0.1.
The optimum condition is 01 to 3 nm / sec.

Further, the gasifiable compound may be H ₂ , He,
It may be appropriately diluted with a gas such as Ne, Ar, Xe, or Kr and introduced into the deposition chamber.

In particular, when depositing a layer having a small band of light absorption or a wide bandgap such as a microcrystalline semiconductor or a-SiC: H, the source gas is diluted with hydrogen gas 2 to 100 times, and the rf energy is relatively large. It is preferable to introduce power. The frequency of rf is 1MHz-100M
Hz is a suitable range, and particularly a frequency near 13.56 MHz is optimum.

Microwave plasma C is used for the p-type layer or the n-type layer.
When depositing by the VD method, the microwave plasma CVD apparatus is preferably a method of introducing microwaves into the deposition chamber through a dielectric window (alumina ceramics or the like) using a waveguide.

The p-type layer or the n-type layer formed by the microwave plasma CVD method is also suitable for the deposition film forming method of the present invention, but a deposition film applicable to a photovoltaic element is formed under wider deposition conditions. can do.

When a p-type layer or an n-type layer is deposited by a microwave plasma CVD method other than the method of the present invention, the substrate temperature in the deposition chamber is 100 to 400 ° C., and the internal pressure is 0.5 to 30 m.
Torr, microwave power 0.01 to 1 W / c
A preferable range of m ³ and microwave frequency is 0.5 to 10 GHz.

Further, the gasifiable compound may be H ₂ , He,
It may be appropriately diluted with a gas such as Ne, Ar, Xe, or Kr and introduced into the deposition chamber.

In particular, when depositing a layer such as a microcrystalline semiconductor or a-SiC: H having a small light absorption or a wide hand gap, the source gas is diluted with hydrogen gas to 2 to 100 times, and the microwave power is relatively high. It is preferable to introduce a large power. i-Type Layer In a photovoltaic device, the i-type layer is an important layer that generates and transports carriers for irradiation light.

The material for the i-type layer need not be a strictly i-type material, and a slightly p-type or slightly n-type material can be used.

The i-type layer of the photovoltaic element of the present invention is an amorphous material such as a-Si: H, a-Si: HX, a-.
SiC: H, a-SiC: HX, a-SiGe: H, a
-SiGe: HX, a-SiGeC: HX, etc. can be mentioned.

In particular, for the i-type layer, an intrinsic material is formed by adding a group III atom and / or a group V atom of the periodic table to the above amorphous material as a valence electron control agent.
Suitable materials may be mentioned.

The hydrogen atom (H, D) or halogen atom (X) contained in the i-type layer serves to compensate dangling bonds of the i-type layer, and the mobility and life of carriers in the i-type layer. To improve the product of Further, it serves to compensate the interface states generated at the interfaces of the p-type layer / i-type layer and the n-type layer / i-type layer, and improves the photovoltaic power, photocurrent and photoresponsiveness of the photovoltaic device. It is effective. The optimum content of hydrogen atoms and / or halogen atoms contained in the i-type layer can be 1 to 40%. In particular, p-type layer / i-type layer, n
A preferable distribution form is one in which the content of hydrogen atoms and / or halogen atoms is largely distributed on each interface side of the type layer / i-type layer, and the content of hydrogen atoms and / or halogen atoms near the interface is included. The amount is 1.1 to 2 of the content in the bulk.
A double range can be mentioned as a preferable range.

The layer thickness of the i-type layer depends on the structure of the photovoltaic element (for example, single cell, double cell, triple cell) and i
Although it is appropriately determined depending on various conditions such as optical and electrical characteristics of the mold layer, 0.1 to 1.0 μm can be mentioned as the optimum layer thickness.

Further, it is preferable that the band gap of the i-type layer is designed to be wide on the interface side of each of the p-type layer / i-type layer and the n-type layer / i-type layer. By designing in this way, the photovoltaic power and photocurrent of the photovoltaic element can be increased, and further photodegradation and the like when used for a long time can be reduced.

The deposited film forming method of the present invention is most suitable for the i-type layer of the photovoltaic element. Transparent electrode As a material preferably used for the transparent electrode, ZnO, Sn
O ₂ , In ₂ O ₃ , ITO, TiO ₂ , CdO, Cd _{2
SnO 4, Bi 2 O 3,} MoO 3, Na x WO 3, and the like.

The transparent electrode is deposited as follows.

The sputtering method and the vacuum evaporation method are the most suitable deposition methods for depositing the transparent electrode.

As a sputtering apparatus suitable for depositing a transparent electrode, a DC magnetron sputtering apparatus schematically shown in FIG. 3 can be mentioned.

A DC magnetron sputtering apparatus schematically shown in FIG. 3 suitable for depositing a transparent electrode includes a deposition chamber 301, a substrate 302, a heater 303, targets 304, 3
08, insulating supports 305, 309, DC power supply 306,
310, shutters 307, 311, vacuum gauge 312, conductance valve 313, gas introduction valves 314, 3
15, mass flow controllers 316, 317 and the like.

In the DC magnetron sputtering apparatus, when a transparent electrode made of indium oxide is deposited on a substrate, a target made of metal indium (In) or indium oxide (In ₂ O ₃ ) is used.

When a transparent electrode made of indium-tin oxide is further deposited on the substrate, the target is metal tin, metal indium or an alloy of metal tin and metal indium, tin oxide, indium oxide, indium-tin oxide, etc. Are used in combination as appropriate.

When depositing by the sputtering method, the substrate temperature is an important factor, and 25 ° C. to 600 ° C. can be mentioned as a preferable range. In addition, as a gas for sputtering when depositing the transparent electrode by a sputtering method, an inert gas such as argon gas (Ar), neon gas (Ne), xenon gas (Xe), and helium gas (He) can be mentioned. Ar gas is the optimum one. Further, it is preferable to add oxygen gas (O ₂ ) to the inert gas as needed. Especially when a metal is used as a target, oxygen gas (O ₂ ) is essential.

Further, when the target is sputtered with the above-mentioned inert gas or the like, the pressure of the discharge space is 0.1 to 50 mTorr in order to perform the sputtering effectively.
Can be mentioned as a preferable range.

In addition, a DC power supply or an rf power supply is suitable as a power supply for the sputtering method. The power for sputtering is 10 to 10
00W is a suitable range.

The deposition rate of the transparent electrode depends on the pressure of the discharge space and the discharge power, and the optimum deposition rate is 0.01
The range is from 10 nm / sec.

The layer thickness of the transparent electrode is preferably deposited under conditions that satisfy the conditions of the antireflection film. As a specific layer thickness of the transparent electrode, 50 to 300 nm can be mentioned as a preferable range.

As a second method suitable for depositing the transparent electrode, a vacuum vapor deposition method can be mentioned.

The vacuum vapor deposition apparatus is, as schematically shown in FIG. 4, a deposition chamber 401, a substrate 402, a heater 403,
The vapor deposition source 404, the vapor deposition source heater 404, the AC power source 406, the shutter 407, the vacuum gauge 408, the conductance valve 409, the gas introduction valve 410, the mass flow controller 411, the leak valve 412, and the film thickness monitor 413 are included.

Suitable vapor deposition sources for depositing transparent electrodes in the vacuum vapor deposition method include metal tin, metal indium, and indium-tin alloy.

The suitable substrate temperature for depositing the transparent electrode is 25 ° C. to 600 ° C.

Further, when depositing the transparent electrode, the pressure in the deposition chamber is reduced to 10 ^-6 Torr or less, and then oxygen gas (O ₂ ) is introduced into the deposition chamber in the range of 5 × 10 ^-5 Torr to 9 × 10 ^-4 Torr. It is necessary to introduce.

By introducing oxygen in this range, the metal vaporized from the vapor deposition source reacts with oxygen in the vapor phase to deposit a good transparent electrode.

Further, plasma may be generated by introducing rf electric power at the above-mentioned degree of vacuum and vapor deposition may be performed through the plasma.

The preferable deposition rate range of the transparent electrode under the above conditions is 0.01 to 10 nm / sec.
If the deposition rate is less than 0.01 nm / sec, the productivity will be reduced, and if it is more than 10 nm / sec, a rough film will be formed and the transmittance, conductivity and adhesion will be reduced.

[0154]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto.

Example 1 An a-Si: H photovoltaic element having the structure shown in FIG. 2A was manufactured as described below.

In this example, as the substrate 201, a 10 cm square stainless steel (SUS304) plate having a mirror-polished surface was used, and a light reflecting layer 202 was formed thereon.
Was formed into a thickness of 0.3 μm by a known vacuum deposition method.

On this, a zinc oxide layer was formed as the reflection increasing layer 203 by using the DC sputtering apparatus shown in FIG. 3 as follows.

After the substrate 302 having silver deposited thereon was attached to the heater 303, the inside of the deposition chamber 301 was evacuated by a pump (not shown). After confirming with the vacuum gauge 312 that the degree of vacuum in the deposition chamber 301 has become 10 ⁻⁵ Torr or less, the heater 303 is energized to change the temperature of the substrate 302 to 4
It was heated and held at 00 ° C.

In the present embodiment, the target 304 is made of sintered zinc oxide powder. Argon gas as a sputter gas is supplied through the gas introduction valve 314 while being adjusted by the mass flow controller 316 so that the flow rate is 25 sccm, and after the flow rate is stabilized, a DC voltage is supplied from the sputter power source 306 to the target 304 and a sputter current. Was set and applied so as to be 0.8 A. The internal pressure during sputtering was kept at 7 mTorr.

As described above, the formation of the zinc oxide layer was started, and after the layer thickness of the zinc oxide layer reached 1.0 μm, power was supplied from the sputtering power source, sputtering gas was supplied, and the heater 303 was supplied. After de-energizing and cooling the substrate, the deposition chamber 30
The inside of 1 was leaked to the atmosphere, and the substrate on which the zinc oxide layer was formed was taken out.

Subsequently, an n-type layer 204, an i-type layer 205 and a p-type layer 206 each made of a-Si: H are formed thereon.
It was formed using the microwave plasma CVD apparatus shown in FIG.

Gas cylinders 1071 to 1076 in FIG.
The raw material gas for forming each semiconductor layer is sealed in. 1071 is SiH ₄ (purity 99.999
%) Gas cylinder, 1072 is GeH ₄ (purity 99.99)
9%) gas cylinder, 1073 is H ₂ (purity 99.999)
9%) gas cylinder, 1074 abbreviated as PH ₃ gas diluted to 10% with H ₂ gas (hereinafter "PH ₃ / H ₂ gas") cylinder, 1075 BF ₃ diluted to 10% with H ₂ gas Gas (hereinafter abbreviated as “BF ₃ / H ₂ gas”) cylinders and 1076 are Ar gas cylinders. When the gas cylinders 1071 to 1076 are attached, SiH ₄ gas is supplied from the gas cylinder 1071 and G is supplied from the gas cylinder 1072.
eH ₄ gas, H ₂ gas from gas cylinder 1073, PH ₃ / H ₂ gas from gas cylinder 1074, gas cylinder 107
BF ₃ / H ₂ gas from No. 5 and Ar gas from the gas cylinder 1076 are introduced into the gas pipes of the valves 1031 to 1036 by opening the valves 1051 to 1056, and the respective pipes are adjusted by the pressure regulators 1061 to 1066. The gas pressure inside was adjusted to ² kg / cm ² .

Valves 1031 to 1036 and deposition chamber 1
It is confirmed that the leak valve 109 of 01 is closed, and that the valves 1041 to 1046 are opened, the conductance (butterfly type) valve 107 is fully opened, and a vacuum pump (not shown) is used. The deposition chamber 101 and the gas pipe are exhausted. When the reading of the vacuum gauge 106 is preferably 1 × 10 ⁻⁴ Torr or less, more preferably 1 × 10 ⁻⁵ Torr or less, the valve 104 is reached.
1 to 1046 are closed.

Next, the valves 1031 to 1036 are gradually opened to let each gas flow through the mass flow controller 10.
21 to 1026.

After the preparation for forming the semiconductor layer is completed as described above, the heater 105 is energized to set the substrate 104 to 3 times.
It was heated and kept at 80 ° C.

Next, the introduction valves 1041, 1043, 1
Open 044 gradually to prevent dust from scattering
H ₄ gas, H ₂ gas, and PH ₃ / H ₂ gas were caused to flow into the deposition chamber 101 through the auxiliary valve 108 and the gas introduction pipe 103. At this time, the SiH ₄ gas flow rate is 10 sccm,
The mass flow controllers 1021, 1023, and 1024 were adjusted so that the H ₂ gas flow rate was 100 sccm and the PH ₃ / H ₂ gas flow rate was 1.0 sccm.

It is preferable to gradually introduce the gas into the deposition chamber 101 and to perform the operation with the shutter 115 closed to prevent dust from adhering to the substrate surface.

When the gas flow rate became stable, the deposition chamber 10
The opening of the conductance valve 107 was adjusted while observing the vacuum gauge 106 so that the pressure in 1 became 5 mTorr. Next, the power of the microwave power source (not shown) is set to 400 W, and the waveguide, the waveguide section 110, and the conductor window 1 (not shown) are set.
Microwave power was introduced into the deposition chamber 101 via 02 to cause microwave glow discharge. DC and rf bias voltages can be applied after the plasma has stabilized,
60 by bias power supply 111 having sufficient power supply capacity
An rf bias of 0 W and a DC bias voltage of +100 V was applied to the bias rod 112. The shutter 115 was opened when the parameters of the plasma and the bias current became constant, and the formation of the n-type layer on the substrate 104 was started. The mesh 113 is removed from the vicinity of the substrate 104.

When the layer thickness of the n-type layer 204 reaches about 20 nm, the shutter 115 is closed, the introduction of microwave power is stopped, the output of the bias power source 111 is cut off, and the introduction valves 1041, 1043, 1044 are closed. Deposition chamber 1
The introduction of gas into the inside of No. 01 was stopped, and the formation of the n-type layer 204 was completed.

Next, the i-type layer 205 was formed as follows. First, the mesh 113 was moved and installed so as to cover the substrate 104. Subsequently, the deposition chamber 101 and the piping were once evacuated to a high vacuum of 10 ⁻⁵ Torr or less, and then the substrate 104 was heated and held at 370 ° C. by the heater 105, and the introduction valve 1041 was opened to supplement 150 sccm of SiH ₄ gas. Valve 108 and gas introduction pipe 1
It was introduced into the deposition chamber 101 through 03. Deposition chamber 101
The opening of the conductance valve 107 was adjusted while observing the vacuum gauge 106 so that the internal pressure became 5 mTorr.
Next, the power of the microwave power source (not shown) is set to 450 W, and the waveguide, the waveguide section 110, and the dielectric window 102 (not shown) are set.
Microwave power was introduced into the deposition chamber 101 through the to generate microwave glow discharge. After plasma is stabilized, rf bias 750 W by the bias power supply 111
Was supplied to the bias rod 112. Further, a DC bias voltage +60 V from the mesh bias power source 114 was applied to the mesh 113. When the parameters such as the state of plasma and the bias current become constant, the shutter 11
5 was opened to start forming an i-type layer on the n-type layer. In addition,
It has been previously confirmed by the above-described method that the microwave energy value is in a microwave energy rate-determining state.

When the thickness of the i-type layer 205 reaches about 270 nm, the shutter 115 is closed, the introduction of microwave power is stopped, the outputs of the bias power sources 111 and 114 are cut off, and the gas is introduced into the deposition chamber 101. Stop the i-type layer 2
The formation of 05 is finished. The deposition rate of the i-type layer is about 10 nm
/ Sec.

Next, the p-type layer 206 was formed as follows. First, the mesh 113 was moved and removed from the vicinity of the substrate 104. Subsequently, the substrate 104 is heated and held at 350 ° C. by the heater 105, and Si is heated.
Auxiliary valve 1 for H ₄ gas, H ₂ gas, and BF ₃ / H ₂ gas
It was introduced into the deposition chamber 101 through 08 and the gas introduction pipe 103. At this time, the SiH ₄ gas flow rate is 10 sccm, H
The mass flow controllers were adjusted so that the ₂ gas flow rate was 100 sccm and the BF ₃ / H ₂ gas flow rate was 1 sccm. The opening of the conductance valve 107 was adjusted while observing the vacuum gauge 106 so that the pressure in the deposition chamber 101 was 5 mTorr. Next, the power of a microwave power source (not shown) is set to 400 W, microwave energy is introduced into the deposition chamber 101 through a waveguide, a waveguide section 110, and a dielectric window 102 (not shown) to perform microwave glow discharge. Caused. After the plasma was stabilized, the bias power supply 111 applied a DC bias voltage of +100 V to the bias rod 112. When the parameters such as the state of plasma and the bias current become constant, the shutter 11
5 was opened to start forming a p-type layer on the i-type layer.

When the p-type layer 206 has a thickness of about 10 nm, the shutter 115 is closed to stop the introduction of microwave power, turn off the output of the bias power source 111, and stop the introduction of gas into the deposition chamber 101. The formation of the p-type layer 206 is completed.

Next, the interior of the deposition chamber 101 and the gas introduction pipe, etc. was repeatedly purged with argon three times, the gas introduction valve was closed, and the leak valve 109 was opened when the substrate temperature fell to an appropriate value to perform deposition. The inside of the chamber 101 was leaked to the atmosphere, and the substrate 104 having the n-type layer, the i-type layer and the p-type layer formed on the surface thereof was taken out from the deposition chamber 101.

In the next step, ITO (In ₂ O ₃ + SnO ₂ ) was formed as a transparent electrode 207 on the p-type layer 206 of the a-Si: H photovoltaic element formed as described above.
It was formed as follows.

The apparatus shown in FIG. 4 was used as a reactive vacuum vapor deposition apparatus.

The substrate 402 having the p-type layer formed thereon was attached to the heater 403, and as the vapor deposition source 404, metal tin and metal indium (both having a purity of 99.999%) were used.
%: 50% After replenishing the mixture, a vacuum pump (not shown) is operated to fully open the conductance valve and the deposition chamber 401.
The inside was evacuated.

After the degree of vacuum in the deposition chamber became 10 ⁻⁵ Torr or less, the heater 403 was energized to keep the temperature of the substrate 402 at 150 ° C.

Subsequently, oxygen gas (O ₂ ) was adjusted by the mass flow controller 411 so that the flow rate was 8 sccm, and introduced into the deposition chamber 401 via the gas introduction valve 410. After the flow rate becomes constant, the conductance valve 409 is adjusted while watching the vacuum gauge 408 to adjust the deposition chamber 4
The degree of vacuum inside 01 was set to 3 × 10 ⁻⁴ Torr.

After the internal pressure became constant, the heater 405 for the vapor deposition source was energized to start heating the vapor deposition source 404.

When the temperature of the vapor deposition source rises and metal tin and indium begin to vaporize, the vaporized metal atoms react with oxygen gas in the deposition chamber, so that the pressure in the deposition chamber slightly decreases. When the fluctuation value of the pressure became 3 × 10 ⁻⁵ Torr, the shutter 407 was opened and the formation of the ITO film on the substrate 402 was started.

The output of the AC power source 406 is adjusted while observing the value of the deposition rate by the film thickness monitor 413 so that the deposition rate becomes substantially constant at about 0.07 nm / sec.
A TO film was formed.

When the film thickness reaches 75 nm, the shutter 407 is closed, the heaters 403 and 405 are deenergized, the gas introduction valve 410 is closed, and the transparent electrode 20 is closed.
The formation of 7 is completed. When the substrate temperature decreased, the leak valve 412 was opened, the inside of the deposition chamber 401 was leaked, and the substrate 402 on which the transparent electrode 207 was formed was taken out.

Next, Al having a layer thickness of 2 μm was deposited as a collector electrode 208 by a resistance heating vacuum deposition method using a mask.
Then, an a-Si: H photovoltaic element (No. Ex-1) was obtained.

As a comparative example, it is the same as the photovoltaic element (No. real-1) under other conditions except that the semiconductor layer was deposited without applying a DC bias voltage to the mesh 113 in the i-type layer forming step. Then, an a-Si: H photovoltaic element (No. ratio -1) was produced.

Pseudo sunlight was produced by using a solar simulator (Yamashita Denso Co., Ltd., YSS-150) for the photovoltaic elements (No. Ex-1) and (No. Ratio-1) produced as described above. (AM-1.5, 100 mW / cm ² )
The current-voltage characteristics were measured under irradiation to determine the photoelectric conversion efficiency. As a result, the photovoltaic element of the comparative example (No.
When the value of 1) is set to 1, the photoelectric conversion efficiency of the photovoltaic element (No. Ex-1) formed using the deposited film forming method of the present invention is dramatically improved to 1.25. I understood it. That is, in the photovoltaic element using the deposited film forming method of the present invention in the formation of the i-type layer that most greatly affects the characteristics of the photovoltaic element, the ionic species that contribute to the improvement of the film characteristics are effectively selected, In addition, the uniformity and characteristics of the deposited film were improved by applying an appropriate acceleration by the electric field between the mesh and the substrate, and as a result, the photoelectric conversion efficiency of the photovoltaic device was dramatically improved. It is considered to be a thing.

Further, 25 small-area photovoltaic elements having the same shape were formed on one substrate, and the variation in photoelectric conversion efficiency of the photovoltaic elements was examined. As a result, it was found that the variation width in the photovoltaic element formed by using the deposited film forming method of the present invention was 0.43 when the variation width in the photovoltaic element of the comparative example was 1. .
That is, i that most affects the characteristics of the photovoltaic element
In the photovoltaic element using the deposited film forming method of the present invention in forming the mold layer, the uniformity of the deposited film is improved by uniformizing the plasma, and as a result, the uniformity of the photovoltaic element is improved. It is considered that the dramatic improvement has been achieved.

Further, the following durability test was conducted in order to investigate the reliability of these photovoltaic elements under actual use conditions.

Photovoltaic device (No. Ex-1) and (N
o. Each of the ratio-1) is polyvinylidene fluoride (VDF)
It is vacuum-sealed with a protective film consisting of 1 and it is used under actual use conditions (installed outdoors, connecting a fixed resistance of 50 ohms to both electrodes).
After leaving for a year, the photoelectric conversion efficiency is evaluated again, and the deterioration rate due to light irradiation, temperature difference, wind and rain, etc. (The value of the photoelectric conversion efficiency damaged by the deterioration is divided by the initial value of the photoelectric conversion efficiency. ) Was investigated. As a result, the photovoltaic element (No.
The actual deterioration rate of -1) was dramatically improved to 0.71 when the deterioration rate of the photovoltaic element (No. ratio -1) was set to 1. That is, in the photovoltaic element using the deposited film forming method of the present invention in the formation of the i-type layer that most greatly affects the characteristics of the photovoltaic element, the activity having energy that contributes to the structural relaxation of the film being deposited is With the presence of species, it is possible to effectively reduce the effects of unnecessary electrons and ions that cause harmful damage to the deposited film, which reduces the disturbance of the network in the deposited film, and as a result, It is considered that the reliability of the electromotive force element has been dramatically improved.

Example 2 An a-SiGe: H photovoltaic element having the structure shown in FIG. 2A was produced as described below.

In this example, as the substrate 201, a stainless steel (SUS304) plate having a 10 cm square and a thickness of 0.1 mm, the surface of which was mirror-polished, was used, and the light reflection layer 202 was formed thereon.
Was formed into a thickness of 0.5 μm by a known vacuum deposition method. At that time, the substrate temperature was set at 350 ° C. to deposit silver to form an uneven structure with a period of about 1 μm and a height difference of about 0.3 μm on the surface of the silver layer.

On this, a zinc oxide layer was formed as the reflection increasing layer 203 in the same manner as in Example 1.

Next, the n-type layer 204 was formed in the same manner as in Example 1, and subsequently, an a-SiGe: H film was formed as the i-type layer 205 as follows.

First, the deposition chamber 101 and the inside of the pipe are temporarily set to 10
After evacuating to a high vacuum of ^-5 Torr or less, the substrate 104 is heated and held at 380 ° C. by the heater 105, the introduction valves 1041 and 1042 are opened, and the SiH ₄ gas 11
0 sccm, GeH ₄ gas 40 sccm auxiliary valve 1
It was introduced into the deposition chamber 101 through 08 and the gas introduction pipe 103. Conductance valve 10 while watching vacuum gauge 106 so that the pressure in deposition chamber 101 becomes 5 mTorr.
The opening of 7 was adjusted. Next, the power of the microwave power source (not shown) is set to 400 W, and the waveguide and the waveguide 11 (not shown) are set.
0 and the dielectric window 102, microwave power was introduced into the deposition chamber 101 to cause microwave glow discharge. After the plasma was stabilized, rf energy of 600 W from the bias power supply 111 was applied to the bias rod 112. A DC bias of +120 V from the mesh bias power source 114 was applied to the mesh 113. When each parameter such as the state of plasma and the bias current became constant, the shutter 115 was opened, and the formation of the i-type layer on the n-type layer was started. It has been previously confirmed that the microwave energy value is in a microwave energy rate-determining state.

When the thickness of the i-type layer 205 reaches about 200 nm, the shutter 115 is closed, the introduction of microwave power is stopped, the outputs of the bias power sources 111 and 114 are cut off, and the gas is introduced into the deposition chamber 101. Stop the i-type layer 2
The formation of 05 is finished. The deposition rate of the i-type layer is about 10 nm
/ Sec.

Subsequently, the p-type layer 206, the transparent electrode 207, and the collector electrode 208 were formed in the same manner as in Example 1 to obtain a photovoltaic element (No. Ex-2).

On the other hand, two types of comparative examples were manufactured. One is that, in the i-type layer forming step, the rf energy is set to 300 W, which is smaller than the microwave energy, and the semiconductor layer is deposited. A-SiG manufactured in the same manner as
e: H photovoltaic element (No. ratio 2-1), and the second one is more than microwave energy required to decompose microwave energy of 500 W and 100% of raw material gas in the i-type layer forming step. Except for the fact that the semiconductor layer is deposited with a large value, the other conditions are the photovoltaic device (N
o. This is an a-SiGe: H photovoltaic element (No. ratio -2-2) manufactured in the same manner as in Example-2).

The photovoltaic elements (No. Ex-2), (No. Ratio 2-1) and (No.
The current-voltage characteristics were measured for the ratio -2-2) in the same manner as in Example 1 to obtain the photoelectric conversion efficiency. As a result, when the value of the photovoltaic device (No. ratio 2-1) of the comparative example is 1, the photovoltaic device (No. real-2) manufactured by using the deposited film forming method of the present invention. It was found that the photoelectric conversion efficiency of 1) was dramatically improved to 1.27. Further, when the same evaluation is performed on the photovoltaic element (No. ratio -2-2), the photoelectric conversion efficiency is 0.93, and the photovoltaic element (No. ratio -2) is
It was inferior to -1).

From the above results, in the photovoltaic element using the deposited film forming method of the present invention in forming the i-type layer that most greatly affects the characteristics of the photovoltaic element, it contributes to the improvement of the characteristics of the deposited film. A large amount of ionic species is generated and is effectively selected, and the uniformity and stability of the plasma are improved, so that the uniformity and characteristics of the deposited film are improved, and as a result, the photovoltaic device is improved. It is considered that the dramatic improvement in the photoelectric conversion efficiency of 1 was achieved.

Example 3 a-Si: H / a-Si having the structure shown in FIG. 2 (b)
A Ge: H double type photovoltaic element was produced as described below. In the photovoltaic device, the first i-type layer is a
-SiGe: H, the second i-type layer is a-
It is composed of Si: H.

In this embodiment, a stainless steel (SUS304) plate having a surface of 10 cm square and a thickness of 0.1 mm whose surface is mirror-polished is used as the substrate 211, and the light reflection layer 212 is formed thereon.
Was formed by a known vacuum deposition method to have an average thickness of 0.5 μm. At that time, the substrate temperature is set to 400 ° C. to deposit silver, and thereby a period of about 1.1 is formed on the surface of the silver layer.
A concavo-convex structure with a height difference of about 0.3 μm was formed.

On this, a zinc oxide layer was formed as the reflection increasing layer 213 in the same manner as in Example 1.

Subsequently, the first n-type layer 214, the a-SiGe: H film as the first i-type layer 215, and the first p-type layer 2 are formed.
16 was formed in the same manner as in Example 2.

Furthermore, a second n-type layer 217, an a-Si: H film as the second i-type layer 218, and a second p-type layer 219.
Was formed in the same manner as in Example 1.

After the above steps are completed, the transparent electrode 220,
The collector electrode 221 was formed in the same manner as in Example 1 to obtain a photovoltaic element (No. Ex-3).

As a comparative example, except that the semiconductor layer was deposited without applying a bias voltage to the mesh 113 in the steps of forming the first and second i-type layers, the other conditions were the photovoltaic element (No. -3) and a-Si: H /
a-SiGe: H double type photovoltaic element (No. ratio-
3) was produced.

With respect to the photovoltaic elements (No. Ex-3) and (No. Ratio-3) produced as described above, the current-voltage characteristics were measured in the same manner as in Example 1 to perform photoelectric conversion. I asked for efficiency. As a result, when the value of the photovoltaic element (No. ratio -3) of the comparative example is 1, the photovoltaic element (No. Ex-3) produced by using the deposited film forming method of the present invention is used. It was found that the photoelectric conversion efficiency was dramatically improved to 1.24. That is, in the photovoltaic element using the deposited film forming method of the present invention in the formation of the i-type layer that most greatly affects the characteristics of the photovoltaic element, the ionic species that contribute to the improvement of the deposited film characteristics are effectively selected. And that the uniformity and characteristics of the deposited film have been improved by improving the uniformity and stability of the plasma, and as a result, a dramatic improvement in the photoelectric conversion efficiency of the photovoltaic device has been achieved. Conceivable.

Further, the same experiment was repeated 10 times to examine the variation in the photoelectric conversion efficiency of the photovoltaic element.
As a result, it was found that the variation width in the photovoltaic element formed by using the deposited film forming method of the present invention is 0.49 when the variation width in the photovoltaic element of the comparative example is 1. It was That is, in the photovoltaic element using the deposited film forming method of the present invention in forming the i-type layer that most greatly affects the characteristics of the photovoltaic element, it is possible to improve the reproducibility of the deposited film by stabilizing the plasma. As a result, it is considered that the reproducibility of the photovoltaic element is dramatically improved.

Example 4 An a-Si: H photovoltaic element having the structure shown in FIG. 2A was produced as described below.

In this embodiment, as the substrate 201, a 10 cm square stainless steel (SUS304) plate having a mirror-polished surface is used, and a light reflecting layer 202 is formed thereon.
Was formed into a thickness of 0.3 μm by a known vacuum deposition method.

On this, a zinc oxide layer was formed as the reflection increasing layer 203 by using the DC sputtering apparatus shown in FIG. 3 as follows.

After the substrate 302 having silver vapor deposited thereon was attached to the heater 303, the inside of the deposition chamber 301 was evacuated by a pump (not shown). After confirming with the vacuum gauge 312 that the degree of vacuum in the deposition chamber 301 has become 10 ⁻⁵ Torr or less, the heater 303 is energized to change the temperature of the substrate 302 to 4
It was heated and held at 00 ° C.

In this example, the target 304 used was a sintered zinc oxide powder. Argon gas as a sputter gas is supplied through the gas introduction valve 314 while being adjusted by the mass flow controller 316 so that the flow rate is 25 sccm, and after the flow rate is stabilized, a DC voltage is supplied from the sputter power source 306 to the target 304 and a sputter current. Was set and applied so as to be 0.8 A. The internal pressure during sputtering was kept at 7 mTorr.

The formation of the zinc oxide layer is started as described above, and after the layer thickness of the zinc oxide layer reaches 1.0 μm, power is supplied from the sputtering power source, the sputtering gas is supplied, and the heater 303 is supplied. Power to the deposition chamber 3 is stopped and the substrate is cooled.
The inside of 01 was leaked to the atmosphere to take out the substrate on which the zinc oxide layer was formed.

Subsequently, an n-type layer 204, an i-type layer 205 and a p-type layer 206 each made of a-Si: H are formed thereon.
It was formed using the microwave plasma CVD apparatus shown in FIG.

Gas cylinders 1071 to 1076 in FIG.
The raw material gas for forming each semiconductor layer is sealed in. 1071 is SiH ₄ (purity 99.999
%) Gas cylinder, 1072 is GeH ₄ (purity 99.99)
9%) gas cylinder, 1073 is H ₂ (purity 99.999)
9%) gas cylinder, 1074 abbreviated as PH ₃ gas diluted to 10% with H ₂ gas (hereinafter "PH ₃ / H ₂ gas") cylinder, 1075 BF ₃ diluted to 10% with H ₂ gas Gas (hereinafter abbreviated as “BF ₃ / H ₂ gas”) cylinders and 1076 are Ar gas cylinders. When the gas cylinders 1071 to 1076 are attached, SiH ₄ gas from the gas cylinder 1071 and G from the gas cylinder 1072
eH ₄ gas, H ₂ gas from gas cylinder 1073, PH ₃ / H ₂ gas from gas cylinder 1074, gas cylinder 107
BF ₃ / H ₂ gas from No. 5 and Ar gas from the gas cylinder 1076 are introduced into the gas pipes of the valves 1031 to 1036 by opening the valves 1051 to 1056, and the respective pipes are adjusted by the pressure regulators 1061 to 1066. The gas pressure inside was adjusted to ² kg / cm ² .

Valves 1031 to 1036 and deposition chamber 1
It is confirmed that the leak valve 109 of 01 is closed, and that the valves 1041 to 1046 are opened, the conductance (butterfly type) valve 107 is fully opened, and a vacuum pump (not shown) is used. The deposition chamber 101 and the gas pipe are exhausted. When the reading of the vacuum gauge 106 is preferably 1 × 10 ⁻⁴ Torr or less, more preferably 1 × 10 ⁻⁵ Torr or less, the valve 104 is reached.
1 to 1046 are closed.

Next, the valves 1031 to 1036 are gradually opened to let each gas flow through the mass flow controller 10.
21 to 1026.

After the preparation for forming the semiconductor layer is completed as described above, the heater 105 is energized to set the substrate 104 to 3 times.
Heated and held at 80 ° C.

Next, the introduction valves 1041, 1043, 1
Open 044 gradually to prevent dust from scattering
H ₄ gas, H ₂ gas, and PH ₃ / H ₂ gas were caused to flow into the deposition chamber 101 through the auxiliary valve 108 and the gas introduction pipe 103. At this time, the SiH ₄ gas flow rate is 10 sccm,
The mass flow controllers 1021, 1023, and 1024 were adjusted so that the H ₂ gas flow rate was 100 sccm and the PH ₃ / H ₂ gas flow rate was 1.0 sccm.

It is preferable to gradually introduce the gas into the deposition chamber 101 and to perform the operation with the shutter 115 closed to prevent dust from adhering to the substrate surface.

The mesh 113 has been removed from the vicinity of the substrate by moving in advance.

When the gas flow rate becomes stable, the deposition chamber 10
The opening of the conductance valve 107 was adjusted while observing the vacuum gauge 106 so that the pressure in 1 became 5 mTorr. Next, the power of the microwave power source (not shown) is set to 350 W, and the waveguide, the waveguide section 110, and the dielectric window 1 (not shown) are set.
Microwave power was introduced into the deposition chamber 101 via 02 to cause microwave glow discharge. After the plasma is stabilized, 500 W rf bias and +80 by the bias power supply 111 capable of supplying DC and rf bias voltages.
A DC bias voltage of V was applied to bias rod 112.
The shutter 115 is opened when each parameter such as the state of plasma and the bias current becomes constant, and the substrate 104 is opened.
The formation of the n-type layer on top was started.

When the layer thickness of the n-type layer 204 reaches about 20 nm, the shutter 115 is closed, the introduction of microwave power is stopped, the rf and DC power supply 111 outputs are shut off, and
The introduction valves 1041, 1043, and 1044 were closed to stop the gas introduction into the deposition chamber 101, and the formation of the n-type layer 204 was completed.

Next, the i-type layer 205 is formed by using the method of the present invention.
Was formed as follows.

First, the mesh 113 is moved to move the substrate 1
The temperature of the mesh 113 is heated and maintained at 200 ° C. by installing it so as to cover 04 and operating the temperature controller 116 for the mesh 113. The material of the mesh 113 used in this example is A.
1 and has a substantially square opening having a side of 0.5 mm and an opening ratio of 50%.

Next, the deposition chamber 101 and the inside of the pipe are temporarily set to 10
After evacuating to a high vacuum of ^-4 Torr or less, the substrate 104 is heated and held at 370 ° C. by the heater 105, the introduction valve 1041 is opened, and 150 sccm of SiH ₄ gas is deposited through the auxiliary valve 108 and the gas introduction pipe 103. It was introduced into the chamber 101. The pressure in the deposition chamber 101 is 7 mTo
The opening of the conductance valve 107 was adjusted while observing the vacuum gauge 106 so that it would be rr. Next, the power of the microwave power source (not shown) is set to 400 W, and the deposition chamber 1 is passed through the waveguide (not shown), the waveguide section 110 and the dielectric window 102.
Microwave power is introduced into 01 to generate microwave glow discharge, and then rf is generated by the bias power supply 111.
A bias of 650 W was supplied to the bias rod 112.

When the parameters of plasma, bias current, etc. became constant, the shutter 115 was opened, and the formation of the i-type layer on the n-type layer was started. It has been previously confirmed by the above-described method that the microwave energy value is in a microwave energy rate-determining state.

When the layer thickness of the i-type layer 205 reaches about 250 nm, the shutter 115 is closed, the introduction of microwave power is stopped, the output of the bias power supply 111 is cut off, and the introduction of gas into the deposition chamber 101 is stopped. The formation of the i-type layer 205 is completed. The deposition rate of the i-type layer was about 9 nm / sec.

Next, the p-type layer 206 was formed as follows. First, the mesh 113 was moved and removed from the vicinity of the substrate 104. Subsequently, the substrate 104 is heated and held at 350 ° C. by the heater 105, and Si is heated.
Auxiliary valve 1 for H ₄ gas, H ₂ gas, and BF ₃ / H ₂ gas
It was introduced into the deposition chamber 101 through 08 and the gas introduction pipe 103. At this time, the SiH ₄ gas flow rate is 10 sccm, H
The mass flow controllers were adjusted so that the ₂ gas flow rate was 100 sccm and the BF ₃ / H ₂ gas flow rate was 1 sccm. The opening of the conductance valve 107 was adjusted while observing the vacuum gauge 106 so that the pressure in the deposition chamber 101 was 5 mTorr. Next, the power of a microwave power source (not shown) is set to 400 W, microwave energy is introduced into the deposition chamber 101 through a waveguide, a waveguide section 110, and a dielectric window 102 (not shown) to perform microwave glow discharge. And then +10 by the bias power supply 111.
A DC bias voltage of 0V was applied to the bias rod 112. When the parameters of the plasma, the bias current, etc. became constant, the shutter 115 was opened, and the formation of the p-type layer on the i-type layer was started.

When the p-type layer 206 has a thickness of about 10 nm, the shutter 115 is closed, the introduction of microwave power is stopped, the output of the bias power supply 111 is cut off, and the introduction of gas into the deposition chamber 101 is stopped. The formation of the p-type layer 206 is completed.

Next, after argon purge inside the deposition chamber 101 and the gas introduction pipe and the like is repeated three times, the gas introduction valve is closed, and when the substrate temperature falls to an appropriate value, the leak valve 109 is opened to deposit. The inside of the chamber 101 was leaked to the atmosphere, and the substrate 104 having the n-type layer, the i-type layer and the p-type layer formed on the surface thereof was taken out from the deposition chamber 101.

In the next step, ITO (In ₂ O ₃ + SnO ₂ ) was formed as a transparent electrode 207 on the p-type layer 206 of the a-Si: H photovoltaic element formed as described above.
Was formed as follows.

The apparatus shown in FIG. 4 was used as a reactive vacuum vapor deposition apparatus.

The substrate 402 on which the p-type layer has been formed is attached to the heater 403, and as the vapor deposition source 404, metal tin and metal indium (both having a purity of 99.999%) are used.
%: 50% After replenishing the mixture, a vacuum pump (not shown) is operated to fully open the conductance valve and the deposition chamber 401.
Evacuate the inside.

After the degree of vacuum in the deposition chamber became 10 ⁻⁶ Torr or less, the heater 403 was energized to maintain the temperature of the substrate 402 at 150 ° C.

Subsequently, oxygen gas (O ₂ ) was adjusted by the mass flow controller 411 so that the flow rate was 8 sccm, and was introduced into the deposition chamber 401 through the gas introduction valve 410. After the flow rate becomes constant, the conductance valve 409 is adjusted while watching the vacuum gauge 408 to adjust the deposition chamber 4
The degree of vacuum inside 01 was set to 3 × 10 ⁻⁴ Torr.

After the internal pressure became constant, the heater 405 for the vapor deposition source was energized to start heating the vapor deposition source 404.

When the temperature of the vapor deposition source rises and tin and indium start to vaporize, the vaporized metal atoms react with oxygen gas in the deposition chamber, so that the pressure in the deposition chamber slightly decreases. When the fluctuation value of this pressure reaches 3 × 10 ⁻⁶ Torr, the shutter 407 is opened and the ITO on the substrate 402 is opened.
The film formation started.

The output of the AC power source 406 is adjusted while observing the value of the deposition rate by the film thickness monitor 413 so that the deposition rate becomes substantially constant at about 0.07 nm / sec.
A TO film was formed.

When the thickness of the ITO film reaches 75 nm, the shutter 407 is closed and the heaters 403 and 4 are heated.
The energization of 05 is stopped, the gas introduction valve 410 is closed, and the formation of the transparent electrode 207 is completed. When the substrate temperature decreased, the leak valve 412 was opened, the inside of the deposition chamber 401 was leaked, and the substrate 402 on which the transparent electrode 207 was formed was taken out.

Next, Al having a layer thickness of 2 μm is deposited as a collecting electrode 208 by a resistance heating vacuum deposition method using a mask.
Then, an a-Si: H photovoltaic element (No. Ex-4) was obtained.

As a comparative example, a photovoltaic element (No. Ex-4) was used under the other conditions except that the preset temperature of the mesh 113 was changed to deposit the semiconductor layer in the i-type layer forming step.
And a-Si: H photovoltaic element (No. ratio -4
-1) to (No. ratio -4-10) were manufactured.

The photovoltaic elements (No. Ex-4) and (No. Ratio-4-1) to (N) manufactured as described above.
o. For the ratio -4-10), using a solar simulator (Yamashita Denso, YSS-150), the simulated sunlight (A
The current-voltage characteristics were measured under irradiation with M-1.5 and 100 mW / cm ² ) to examine the relationship between the preset temperature of the mesh and the photoelectric conversion efficiency during the formation of the i-type layer. The results are standardized and shown in FIG. As is clear from this result, the photoelectric conversion efficiency of the photovoltaic element formed by using the deposited film forming method of the present invention is as high as that of the photovoltaic element formed by not using the method of the present invention. It turns out that it has improved dramatically from the efficiency. That is, in the photovoltaic element using the deposited film forming method of the present invention in the formation of the i-type layer that most greatly affects the characteristics of the photovoltaic element, active species that contribute to the improvement of the film characteristics are effectively selected, It is also considered that the characteristics of the deposited film were improved due to the abundant supply to the surface of the deposited film, and as a result, the photoelectric conversion efficiency of the photovoltaic device was dramatically improved.

Further, the following durability test was conducted in order to investigate the reliability of these photovoltaic elements under actual use conditions.

Photovoltaic device (No. Ex-4) and (N
o. Each of the ratios 4-1) to (No. ratio -4-10) is vacuum-sealed with a protective film made of polyvinylidene fluoride (VDF), and under actual use conditions (installed outdoors, 50 on both electrodes).
After placing it for 1 year in a fixed resistance of ohms, the photoelectric conversion efficiency is evaluated again, and the deterioration rate due to light irradiation, temperature difference, wind and rain, etc. The value obtained by dividing by the value of photoelectric conversion efficiency) was obtained, and the relationship between the set temperature of the mesh and the deterioration rate during the formation of the i-type layer was investigated.
The results are standardized and shown in FIG. As is clear from this result, the reliability of the photovoltaic element formed by using the deposited film forming method of the present invention is as high as that of the photovoltaic element formed by not using the deposited film forming method of the present invention. It turned out that it has improved dramatically from the reliability. That is, in the photovoltaic element using the deposited film forming method of the present invention in the formation of the i-type layer that largely affects the reliability of the photovoltaic element, active species that contribute to the improvement of the deterioration resistance of the deposited film are effective. It is considered that the deterioration of the deposited film is improved by the above selection and the abundant supply to the surface of the deposited film, and as a result, the reliability of the photovoltaic element is dramatically improved.

Example 5 An a-SiGe: H photovoltaic element having the structure shown in FIG. 2A was produced as described below.

In this example, as the substrate 201, a 10 cm square stainless steel (SUS304) plate having a mirror-polished surface was used, and a light reflecting layer 202 was formed thereon.
Was formed into a thickness of 0.5 μm by a known vacuum deposition method. At that time, the substrate temperature was set at 350 ° C. to deposit silver to form an uneven structure with a period of about 1 μm and a height difference of about 0.3 μm on the surface of the silver layer.

On this, a zinc oxide layer was formed as the reflection increasing layer 203 in the same manner as in Example 1.

Next, the n-type layer 204 was formed in the same manner as in Example 4, and subsequently, an a-SiGe: H film was formed as the i-type layer 205 as follows.

First, the deposition chamber 101 and the inside of the pipe are once
After evacuating to a high vacuum of ^-5 Torr or less, the substrate 104 is heated and held at 380 ° C. by the heater 105, the introduction valves 1041 and 1042 are opened, and the SiH ₄ gas 12
0 sccm, GeH ₄ gas 30 sccm auxiliary valve 1
It was introduced into the deposition chamber 101 through 08 and the gas introduction pipe 103. Conductance valve 10 while watching vacuum gauge 106 so that the pressure in deposition chamber 101 becomes 5 mTorr.
The opening of 7 was adjusted. Next, the power of the microwave power source (not shown) is set to 350 W, and the waveguide and the waveguide section 11 (not shown) are set.
0 and the dielectric window 102 to introduce microwave power into the deposition chamber 101 to cause microwave glow discharge,
After the plasma is stabilized, the bias power supply 111 causes r
F energy of 550 W was applied to the bias rod 112.
In addition, by operating the temperature controller 116 for the mesh 113, the temperature of the mesh 113 is increased to 200 ° C.
Heat and store. When parameters such as the state of plasma and bias current became constant, the shutter 115 was opened, and formation of the i-type layer on the n-type layer was started. It has been previously confirmed that the microwave energy value is in a microwave energy rate-determining state. The mesh 113 used in this embodiment is made of SUS.
And has a substantially square opening with a side of 0.75 mm and an opening ratio of 70%.

When the thickness of the i-type layer 205 reaches approximately 230 nm, the shutter 115 is closed, the introduction of microwave power is stopped, the outputs of the bias power sources 111 and 116 are cut off, and the gas is introduced into the deposition chamber 101. Stop the i-type layer 2
The formation of 05 is finished. The deposition rate of the i-type layer is about 9 nm /
It was sec.

Subsequently, a p-type layer 206, a transparent electrode 207, and a collector electrode 208 were formed in the same manner as in Example 4 to obtain a photovoltaic element (No. Ex-5).

On the other hand, two types of comparative examples were manufactured. One is that in the i-type layer forming step, the rf energy supplied from the bias rod is set to 300 W, which is a value smaller than the microwave energy, and the semiconductor layer is deposited. The actual a-5) is an a-SiGe: H photovoltaic element (No. ratio -5-1) manufactured by the same method as the actual -5), and another one is 500 W of microwave energy and source gas in the i-type layer forming step. Was prepared under the same conditions as the photovoltaic element (No. Ex-5), except that the semiconductor layer was deposited at a value larger than the microwave energy required for 100% decomposition of a. -SiGe: H photovoltaic element (No. ratio-5-
2).

Photovoltaic devices (No. Ex-5), (No. Ratio-5-1) and (No.
The current-voltage characteristics were measured for the ratio -5-2) in the same manner as in Example 4 to obtain the photoelectric conversion efficiency. As a result, when the value of the photovoltaic element (No. ratio -5-1) of the comparative example is set to 1, the photovoltaic element (No. real-number) formed by using the deposited film forming method of the present invention. It was found that the photoelectric conversion efficiency of 5) was dramatically improved to 1.31. Further, when the same evaluation is performed on the photovoltaic element (No. ratio -5-2), the photoelectric conversion efficiency is 0.93, and the photovoltaic element (No. ratio -5).
It was inferior to -1).

From the above results, in the photovoltaic element using the deposited film forming method of the present invention in the formation of the i-type layer that most greatly affects the characteristics of the photovoltaic element, the electrical characteristics and deterioration resistance of the deposited film are obtained. The ion species that contribute to the improvement of the plasma property are effectively selected and are abundantly supplied to the surface of the deposited film, and the uniformity and stability of the deposited film are improved by improving the plasma uniformity and stability. As a result, it is considered that the photoelectric conversion efficiency of the photovoltaic element has been dramatically improved.

Example 6 a-Si: H / a-Si having the structure shown in FIG.
A Ge: H double type photovoltaic element was produced as described below. In the photovoltaic device, the first i-type layer is a
-SiGe: H, the second i-type layer is a-
It is composed of Si: H.

In this example, as the substrate 211, a 10 cm square stainless steel (SUS304) plate having a mirror-polished surface was used, and a light reflection layer 212 was formed thereon.
Was formed by a known vacuum deposition method to have an average thickness of 0.5 μm. At that time, the substrate temperature is set to 400 ° C. to deposit silver, and thereby a period of about 1.1 is formed on the surface of the silver layer.
A concavo-convex structure with a height difference of about 0.3 μm was formed.

On this, a zinc oxide layer was formed as the reflection increasing layer 213 in the same manner as in Example 1.

Subsequently, the first n-type layer 214, the a-SiGe: H film as the first i-type layer 215, and the first p-type layer 2 are formed.
16 was formed in the same manner as in Example 2.

Further, the second n-type layer 217, the a-Si: H film as the second i-type layer 218, and the second p-type layer 219.
Was formed in the same manner as in Example 1.

After the above steps are completed, the transparent electrode 220,
The collector electrode 221 was formed in the same manner as in Example 4 to obtain a photovoltaic element (No. Ex-6).

As a comparative example, except that the mesh 113 was not placed in the vicinity of the substrate 104 in the first and second i-type layer forming steps and a semiconductor layer was deposited, the other conditions were the photovoltaic element ( No. Ex.-6) and a-Si: H
/ A-SiGe: H double type photovoltaic element (No. ratio-
6) was produced.

With respect to the photovoltaic elements (No. Ex-6) and (No. Ratio-6) produced as described above, the current-voltage characteristics were measured in the same manner as in Example 1 to perform photoelectric conversion. I asked for efficiency. As a result, when the value of the photovoltaic element (No. ratio-6) of the comparative example is 1, the photovoltaic element (No. Ex-6) formed by using the deposited film forming method of the present invention. It was found that the photoelectric conversion efficiency of was dramatically improved to 1.35. That is, in the photovoltaic element using the deposited film forming method of the present invention in the formation of the i-type layer that most greatly affects the characteristics of the photovoltaic element, the ionic species that contribute to the improvement of the deposited film characteristics are effectively selected. And that the uniformity and characteristics of the deposited film have been improved by improving the uniformity and stability of the plasma, and as a result, a dramatic improvement in the photoelectric conversion efficiency of the photovoltaic device has been achieved. Conceivable.

Further, the same experiment was repeated 10 times to examine the variation in the photoelectric conversion efficiency of the photovoltaic element.
As a result, it was found that the variation width in the photovoltaic element formed by using the deposited film forming method of the present invention is 0.46 when the variation width in the photovoltaic element of the comparative example is 1. It was That is, in the photovoltaic device using the deposition forming method of the present invention in the formation of the i-type layer that most greatly affects the characteristics of the photovoltaic device, the reproducibility of the deposited film is improved by stabilizing the plasma. As a result, it is considered that the reproducibility of the photovoltaic element has been dramatically improved.

Example 7 An a-Si: H photovoltaic device having the structure shown in FIG. 2A was manufactured as described below.

In this example, as the substrate 201, a 10 cm square stainless steel (SUS304) plate having a mirror-polished surface was used, and a light reflection layer 202 was formed thereon.
Was formed into a thickness of 0.3 μm by a known vacuum deposition method.

On this, a zinc oxide layer as the reflection increasing layer 203 was formed as follows using the DC sputtering apparatus shown in FIG.

After the substrate 302 on which silver was vapor-deposited was attached to the heater 303, the inside of the deposition chamber 301 was evacuated by a pump (not shown). After confirming with the vacuum gauge 312 that the degree of vacuum in the deposition chamber 301 has become 10 ⁻⁵ Torr or less, the heater 303 is energized to change the temperature of the substrate 302 to 4
It was heated and held at 00 ° C.

In this example, the target 304 used was a zinc oxide powder sintered. Argon gas as a sputter gas is supplied through the gas introduction valve 314 while being adjusted by the mass flow controller 316 so that the flow rate is 25 sccm, and after the flow rate is stabilized, a DC voltage is supplied from the sputter power source 306 to the target 304 and a sputter current. Was set and applied so as to be 0.8 A. The internal pressure during sputtering was kept at 7 mTorr.

As described above, the formation of the zinc oxide layer was started, and after the layer thickness of the zinc oxide layer reached 1.0 μm, power was supplied from the sputtering power source, sputtering gas was supplied, and the heater 303 was supplied. After de-energizing and cooling the substrate, the deposition chamber 30
The inside of 1 was leaked to the atmosphere, and the substrate on which the zinc oxide layer was formed was taken out.

Subsequently, an n-type layer 204, an i-type layer 205 and a p-type layer 206 each made of a-Si: H are formed thereon.
It was formed using the microwave plasma CVD apparatus shown in FIG.

Gas cylinders 1071 to 1076 in FIG.
The raw material gas for forming each semiconductor layer is sealed in. 1071 is SiH ₄ (purity 99.999
%) Gas cylinder, 1072 is GeH ₄ (purity 99.99)
9%) gas cylinder, 1073 is H ₂ (purity 99.999)
9%) gas cylinder, 1074 abbreviated as PH ₃ gas diluted to 10% with H ₂ gas (hereinafter "PH ₃ / H ₂ gas") cylinder, 1075 BF ₃ diluted to 10% with H ₂ gas Gas (hereinafter abbreviated as “BF ₃ / H ₂ gas”) cylinders and 1076 are Ar gas cylinders. When the gas cylinders 1071 to 1076 are attached, SiH ₄ gas from the gas cylinder 1071 and G from the gas cylinder 1072
eH ₄ gas, H ₂ gas from gas cylinder 1073, PH ₃ / H ₂ gas from gas cylinder 1074, gas cylinder 107
BF ₃ / H ₂ gas from No. 5 and Ar gas from the gas cylinder 1076 are introduced into the gas pipes of the valves 1031 to 1036 by opening the valves 1051 to 1056, and the respective pipes are adjusted by the pressure regulators 1061 to 1066. The gas pressure inside was adjusted to ² kg / cm ² .

Valves 1031 to 1036 and deposition chamber 1
It is confirmed that the leak valve 109 of 01 is closed, and that the valves 1041 to 1046 are opened, the conductance (butterfly type) valve 107 is fully opened, and a vacuum pump (not shown) is used. The deposition chamber 101 and the gas pipe are exhausted. When the reading of the vacuum gauge 106 is preferably 1 × 10 ⁻⁴ Torr or less, more preferably 1 × 10 ⁻⁵ Torr or less, the valve 104 is reached.
1 to 1046 are closed.

Next, the valves 1031 to 1036 are gradually opened to let each gas flow through the mass flow controller 10.
21 to 1026.

After the semiconductor layer was prepared for preparation as described above, the heater 105 was energized to heat and hold the substrate 104 at 380 ° C.

Next, the introduction valves 1041, 1043, 1
Open 044 gradually to prevent dust from scattering
H ₄ gas, H ₂ gas, and PH ₃ / H ₂ gas were caused to flow into the deposition chamber 101 through the auxiliary valve 108 and the gas introduction pipe 103. At this time, the SiH ₄ gas flow rate is 10 sccm,
The mass flow controllers 1021, 1023, and 1024 were adjusted so that the H ₂ gas flow rate was 100 sccm and the PH ₃ / H ₂ gas flow rate was 1.0 sccm.

It is preferable to gradually introduce the gas into the deposition chamber 101 and to carry out this with the shutter 115 closed so as to prevent dust from adhering to the substrate surface.

When the gas flow rate became stable, the deposition chamber 10
The opening of the conductance valve 107 was adjusted while observing the vacuum gauge 106 so that the pressure in 1 became 5 mTorr. Next, the power of the microwave power source (not shown) is set to 400 W, and the waveguide, the waveguide section 110, and the dielectric window 1 (not shown) are set.
Microwave power was introduced into the deposition chamber 101 via 02 to cause microwave glow discharge. After the plasma is stabilized, 600 W rf bias and +10 by a bias power supply 111 capable of supplying DC and rf bias voltages.
A DC bias voltage of 0V was applied to the bias rod 112. When each parameter such as the state of plasma and the bias current becomes constant, the shutter 115 is opened and the substrate 1
The formation of an n-type layer on 04 was started. The mesh 11
It has been removed from near substrate 104 by moving 3.

When the layer thickness of the n-type layer 204 reaches about 20 nm, the shutter 115 is closed, the introduction of microwave power is stopped, the rf and DC power supply 111 outputs are cut off, and
The introduction valves 1041, 1043, and 1044 were closed to stop the gas introduction into the deposition chamber 101, and the formation of the n-type layer 204 was completed.

Next, the i-type layer 205 was formed as follows. First, the mesh 113 was moved and installed so as to cover the substrate 104. Subsequently, the deposition chamber 101 and the piping were once evacuated to a high vacuum of 10 ⁻⁵ Torr or less, and then the substrate 104 was heated and held at 370 ° C. by the heater 105, and the introduction valve 1041 was opened to supplement 150 sccm of SiH ₄ gas. Valve 108 and gas introduction pipe 1
It was introduced into the deposition chamber 101 through 03. Deposition chamber 101
The opening of the conductance valve 107 was adjusted while observing the vacuum gauge 106 so that the internal pressure became 5 mTorr.
Next, the power of the microwave power source (not shown) is set to 450 W, and the waveguide, the waveguide section 110, and the dielectric window 102 (not shown) are set.
Microwave power is introduced into the deposition chamber 101 through a microwave glow discharge to generate a microwave glow discharge, and then an rf bias 750 W from a bias power source 111 is applied to the bias rod 112.
Supplied to. Further, the rf bias voltage from the mesh rf bias power supply 117 is applied to reduce the rf energy of 100.
W was supplied from the mesh 113. When each parameter such as the state of plasma and the bias current became constant, the shutter 115 was opened, and the formation of the i-type layer on the n-type layer was started. It has been previously confirmed by the above-described method that the microwave energy value is in a microwave energy rate-determining state.

When the thickness of the i-type layer 205 reaches about 270 nm, the shutter 115 is closed, the introduction of microwave power is stopped, the bias power sources 111 and 117 are turned off, and gas is introduced into the deposition chamber 101. Stop the i-type layer 2
The formation of 05 is finished. The deposition rate of the i-type layer is about 10 nm
/ Sec.

Next, the p-type layer 206 was formed as follows. First, the mesh 113 was moved and removed from the vicinity of the substrate 104. Subsequently, the substrate 104 is heated and held at 350 ° C. by the heater 105, and Si is heated.
Auxiliary valve 1 for H ₄ gas, H ₂ gas, and BF ₃ / H ₂ gas
It was introduced into the deposition chamber 101 through 08 and the gas introduction pipe 103. At this time, the SiH ₄ gas flow rate is 10 sccm, H
The mass flow controllers were adjusted so that the ₂ gas flow rate was 100 sccm and the BF ₃ / H ₂ gas flow rate was 1 sccm. The opening of the conductance valve 107 was adjusted while observing the vacuum gauge 106 so that the pressure in the deposition chamber 101 was 5 mTorr. Next, the power of a microwave power source (not shown) is set to 400 W, microwave energy is introduced into the deposition chamber 101 through a waveguide, a waveguide section 110, and a dielectric window 102 (not shown) to perform microwave glow discharge. And then +10 by the bias power supply 111.
A DC bias voltage of 0V was applied to the bias rod 112. When the parameters of the plasma, the bias current, etc. became constant, the shutter 115 was opened, and the formation of the p-type layer on the i-type layer was started.

When the layer thickness of the p-type layer 206 reaches about 10 nm, the shutter 115 is closed, the introduction of microwave power is stopped, the output of the bias power source 111 is cut off, and the introduction of gas into the deposition chamber 101 is stopped. The formation of the p-type layer 206 is completed.

Next, the interior of the deposition chamber 101 and the gas inlet pipe is repeatedly purged with argon three times, the gas inlet valve is closed, and when the substrate temperature drops to an appropriate value, the leak valve 106 is opened to deposit. The inside of the chamber 101 was leaked to the atmosphere, and the substrate 104 having the n-type layer, the i-type layer and the p-type layer formed on the surface thereof was taken out from the deposition chamber 101.

In the next step, ITO (In ₂ O ₃ + SnO ₂ ) was formed as a transparent electrode 207 on the p-type layer 206 of the a-Si: H photovoltaic element formed as described above.
It was formed as follows.

The apparatus shown in FIG. 4 was used as a reactive vacuum vapor deposition apparatus.

The substrate 402 on which the p-type layer is formed is attached to the heater 403, and as the vapor deposition source 404, metal tin and metal indium (both having a purity of 99.999%) are used.
%: 50% After replenishing the mixture, a vacuum pump (not shown) is operated to fully open the conductance valve and the deposition chamber 401.
Evacuate the inside.

After the vacuum degree in the deposition chamber became 10 ⁻⁶ Torr or less, the heater 403 was energized to keep the temperature of the substrate 402 at 150 ° C.

Subsequently, oxygen gas (O ₂ ) was adjusted by the mass flow controller 411 so that the flow rate was 8 sccm, and introduced into the deposition chamber 401 through the gas introduction valve 410. After the flow rate becomes constant, the conductance valve 409 is adjusted while watching the vacuum gauge 408 to adjust the deposition chamber 4
The degree of vacuum inside 01 was set to 3 × 10 ⁻⁴ Torr.

After the internal pressure became constant, the heater 405 for the vapor deposition source was energized to start heating the vapor deposition source 404.

When the temperature of the vapor deposition source rises and metal tin and indium start to vaporize, the vaporized metal atoms react with oxygen gas in the deposition chamber, so that the pressure in the deposition chamber slightly decreases. When the fluctuation value of the pressure became 3 × 10 ⁻⁵ Torr, the shutter 407 was opened and the formation of the ITO film on the substrate 402 was started.

While monitoring the value of the deposition rate by the film thickness monitor 413, the output of the AC power source 406 is adjusted so that the deposition rate becomes substantially constant at about 0.07 nm / sec.
A TO film was formed.

When the film thickness reaches 75 nm, the shutter 407 is closed, the heaters 403 and 405 are de-energized, the gas introduction valve 410 is closed, and the transparent electrode 20 is closed.
The formation of 7 is completed. When the substrate temperature decreased, the leak valve 412 was opened, the inside of the deposition chamber 401 was leaked, and the substrate 402 on which the transparent electrode 207 was formed was taken out.

Next, as the collector electrode 208, Al having a layer thickness of 2 μm was deposited by a resistance heating vacuum deposition method using a mask.
Then, an a-Si: H photovoltaic element (No. Ex-7) was obtained.

As a comparative example, the other conditions are the same as those of the photovoltaic element (No. real-7) except that the semiconductor layer is deposited without applying the rf bias voltage to the mesh 113 in the i-type layer forming step. Then, an a-Si: H photovoltaic element (No. ratio -7) was produced.

[0297] A solar simulator (Yamashita Denso Co., Ltd., YSS-150) was used for the photovoltaic elements (No. Ex-7) and (No. Ratio-7) produced as described above to simulate sunlight. (AM-1.5, 100 mW / cm ² )
The current-voltage characteristics were measured under irradiation to determine the photoelectric conversion efficiency. As a result, the photovoltaic element of the comparative example (No.
When the value of 7) is set to 1, the photoelectric conversion efficiency of the photovoltaic element (No. Ex-7) formed by using the deposited film forming method of the present invention is dramatically improved to 1.22. I found out that That is, in the photovoltaic element using the deposited film forming method of the present invention in the formation of the i-type layer that most greatly affects the characteristics of the photovoltaic element, the ionic species that contribute to the improvement of the film characteristics are effectively selected, Moreover, the uniformity and characteristics of the deposited film have been improved by being appropriately accelerated by the electric field between the mesh and the substrate, and as a result, the photoelectric conversion efficiency of the photovoltaic device has been dramatically improved. it is conceivable that.

Further, the same experiment was repeated 10 times to examine the variation in the photoelectric conversion efficiency of the photovoltaic element.
As a result, it was found that the variation width in the photovoltaic element formed by using the deposited film forming method of the present invention is 0.47 when the variation width in the photovoltaic element of the comparative example is 1. It was That is, in the photovoltaic element using the deposited film forming method of the present invention in forming the i-type layer that most greatly affects the characteristics of the photovoltaic element, it is possible to improve the reproducibility of the deposited film by stabilizing the plasma. As a result, it is considered that the reproducibility of the photovoltaic element is dramatically improved.

Further, the following durability test was conducted in order to investigate the reliability of these photovoltaic elements under actual use conditions.

Photovoltaic device (No. Ex-7) and (N
o. Each of the ratio -7) is polyvinylidene fluoride (VDF)
It is vacuum-sealed with a protective film consisting of 1 and it is used under actual use conditions (installed outdoors, connecting a fixed resistance of 50 ohms to both electrodes).
After leaving for a year, the photoelectric conversion efficiency is evaluated again, and the deterioration rate due to light irradiation, temperature difference, wind and rain, etc. (The value of the photoelectric conversion efficiency damaged by the deterioration is divided by the initial value of the photoelectric conversion efficiency. ) Was investigated. As a result, the photovoltaic element (No.
The actual deterioration rate of -7) was dramatically improved to 0.66 when the deterioration rate of the photovoltaic element (No. ratio -7) was set to 1. That is, in the photovoltaic element using the deposited film forming method of the present invention in the formation of the i-type layer that most greatly affects the characteristics of the photovoltaic element, the activity having energy that contributes to the structural relaxation of the film being deposited is With the presence of species, it is possible to effectively reduce the effects of unnecessary electrons and ions that cause harmful damage to the deposited film, which reduces the disturbance of the network in the deposited film, and as a result, It is considered that the reliability of the electromotive force element has been dramatically improved.

Example 8 An a-SiGe: H photovoltaic device having the structure shown in FIG. 2A was produced as described below.

In this embodiment, as the substrate 201, a stainless steel (SUS304) plate having a 10 cm square and a thickness of 0.1 mm whose surface is mirror-polished is used, and a light reflection layer 202 is formed thereon.
Was formed into a thickness of 0.5 μm by a known vacuum deposition method. At that time, the substrate temperature was set at 350 ° C. to deposit silver to form an uneven structure with a period of about 1 μm and a height difference of about 0.3 μm on the surface of the silver layer.

On this, a zinc oxide layer was formed as the reflection increasing layer 203 in the same manner as in Example 7.

Next, the n-type layer 204 was formed in the same manner as in Example 7, and subsequently, an a-SiGe: H film was formed as the i-type layer 205 as follows.

First, the inside of the deposition chamber 101 and the piping is once set to 10
After evacuating to a high vacuum of ^-5 Torr or less, the substrate 104 is heated and held at 380 ° C. by the heater 105, the introduction valves 1041 and 1042 are opened, and the SiH ₄ gas 12
0 sccm, GeH ₄ gas 30 sccm auxiliary valve 1
It was introduced into the deposition chamber 101 through 08 and the gas introduction pipe 103. Conductance valve 10 while watching vacuum gauge 106 so that the pressure in deposition chamber 101 becomes 5 mTorr.
The opening of 7 was adjusted. Next, the power of the microwave power source (not shown) is set to 400 W, and the waveguide and the waveguide 11 (not shown) are set.
0 and the dielectric window 102 to introduce microwave power into the deposition chamber 101 to cause microwave glow discharge,
After the plasma is stabilized, the bias power supply 111 causes r
F energy of 600 W was applied to the bias rod 112.
Further, the rf bias voltage from the mesh bias power supply 117 is applied to the mesh 113, and the rf energy is 80 W.
Was supplied from the mesh. When each parameter such as the state of plasma and the bias current became constant, the shutter 115 was opened, and the formation of the i-type layer on the n-type layer was started. It has been previously confirmed that the microwave energy value is in a microwave energy rate-determining state.

When the thickness of the i-type layer 205 reaches approximately 230 nm, the shutter 115 is closed, the introduction of microwave power is stopped, the outputs of the bias power sources 111 and 117 are cut off, and the gas is introduced into the deposition chamber 101. Stop the i-type layer 2
The formation of 05 is finished. The deposition rate of the i-type layer is about 10 nm
/ Sec.

Subsequently, a p-type layer 206, a transparent electrode 207 and a collector electrode 208 were formed in the same manner as in Example 7 to obtain a photovoltaic element (No. Ex-8).

On the other hand, two types of comparative examples were manufactured. One is that in the i-type layer forming step, the rf energy supplied from the bias rod is set to 300 W, which is a value smaller than the microwave energy, and the semiconductor layer is deposited. Example 8) An a-SiGe: H photovoltaic element (No. ratio -8-1) manufactured in the same manner as Example 8), and another one is 500 W of microwave energy and source gas in the i-type layer forming step. Was prepared under the same conditions as the photovoltaic element (No. real-8) except that the semiconductor layer was deposited at a value higher than the microwave energy required for 100% decomposition. -SiGe: H photovoltaic element (No. ratio -8-
2).

Photovoltaic devices (No. Ex-8), (No. Ratio-8-1) and (No.
The current-voltage characteristics were measured for the ratio -8-2) in the same manner as in Example 7 to obtain the photoelectric conversion efficiency. As a result, when the value of the photovoltaic element (No. ratio −8-1) of the comparative example is 1, the photovoltaic element (No. actual −) formed by using the deposited film forming method of the present invention. It was found that the photoelectric conversion efficiency of 8) was dramatically improved to 1.23. Further, when the same evaluation is performed on the photovoltaic element (No. ratio -8-2), the photoelectric conversion efficiency is 0.89, and the photovoltaic element (No. ratio -8).
It was inferior to -1).

From the above results, in the photovoltaic element using the deposited film forming method of the present invention in the formation of the i-type layer that most greatly affects the characteristics of the photovoltaic element, it contributes to the improvement of the characteristics of the deposited film. The uniformity and characteristics of the deposited film are improved by the effective selection of ion species and the improvement of plasma uniformity and stability. As a result, the photoelectric conversion efficiency of the photovoltaic device is dramatically improved. Is considered to have been achieved.

Example 9 a-Si: H / a-Si having the structure shown in FIG.
A Ge: H double type photovoltaic element was produced as described below. In the photovoltaic device, the first i-type layer is a
-SiGe: H, the second i-type layer is a-
It is composed of Si: H.

In this embodiment, as the substrate 211, a 10 cm square stainless steel (SUS304) plate having a mirror-polished surface is used, and a light reflection layer 212 is formed thereon.
Was formed by a known vacuum deposition method to have an average thickness of 0.5 μm. At that time, the substrate temperature is set to 400 ° C. to deposit silver, and thereby a period of about 1.1 is formed on the surface of the silver layer.
A concavo-convex structure with a height difference of about 0.3 μm was formed.

On this, a zinc oxide layer was formed as the reflection increasing layer 213 in the same manner as in Example 7.

Subsequently, the first n-type layer 214, the a-SiGe: H film as the first i-type layer 215, and the first p-type layer 2 are formed.
16 was formed in the same manner as in Example 8.

Further, the second n-type layer 217, the a-Si: H film as the second i-type layer 218, and the second p-type layer 219.
Was formed in the same manner as in Example 7.

After the above steps are completed, the transparent electrode 220,
The collector electrode 221 was formed in the same manner as in Example 7 to obtain a photovoltaic element (No. Ex-9).

As a comparative example, except that the semiconductor layer was deposited without applying the rf bias voltage to the mesh 113 in the steps of forming the first and second i-type layers, the other conditions were the photovoltaic element (No. Equal to the actual −9) and a-Si:
An H / a-SiGe: H double photovoltaic element (No. ratio -9) was produced.

With respect to the photovoltaic elements (No. Ex-9) and (No. Ratio-9) produced as described above, the current-voltage characteristics were measured in the same manner as in Example 7, and photoelectric conversion was performed. I asked for efficiency. As a result, when the value of the photovoltaic element (No. ratio-9) of the comparative example is 1, the photovoltaic element (No. Ex-9) formed by using the deposited film forming method of the present invention. It was found that the photoelectric conversion efficiency of 1. was dramatically improved to 1.20. That is, in the photovoltaic element using the deposited film forming method of the present invention in the formation of the i-type layer that most greatly affects the characteristics of the photovoltaic element, the ionic species that contribute to the improvement of the deposited film characteristics are effectively selected. And that the uniformity and characteristics of the deposited film have been improved by improving the uniformity and stability of the plasma, and as a result, a dramatic improvement in the photoelectric conversion efficiency of the photovoltaic device has been achieved. Conceivable.

Further, the same experiment was repeated 10 times to examine the variation in the photoelectric conversion efficiency of the photovoltaic element.
As a result, it was found that the variation width of the photovoltaic element formed by using the deposited film forming method of the present invention was 0.39 when the variation width of the photovoltaic element of the comparative example was 1. It was That is, in the photovoltaic element using the deposited film forming method of the present invention in forming the i-type layer that most greatly affects the characteristics of the photovoltaic element, it is possible to improve the reproducibility of the deposited film by stabilizing the plasma. As a result, it is considered that the reproducibility of the photovoltaic element is dramatically improved.

[0320]

INDUSTRIAL APPLICABILITY In a microwave plasma CVD method in which a raw material gas for forming a deposited film is decomposed by microwave energy under a low pressure to form a deposited film on a substrate, an internal pressure of 50 mTorr
At a vacuum degree of r or less, the microwave energy smaller than the microwave energy required for 100% decomposition of the raw material gas is applied to the raw material gas, and the rf energy larger than the microwave energy to be applied is applied to the raw material gas. And applying a DC bias voltage to the mesh by interposing a mesh made of a conductive metal between the substrate and the space where the source gas is mainly decomposed by the microwave energy to act on the mesh. The following effects were obtained by using the deposited film forming method of the present invention characterized by:

(1) It has become possible to form a deposited film of a non-single-crystal semiconductor film, which has excellent electrical characteristics and little photodegradation even when the deposition rate is increased to several nm / sec or more.

(2) By increasing the uniformity and stability of plasma, unevenness in the thickness and characteristics of the deposited film formed is reduced, and as a result, for photovoltaic devices, thin film transistors, sensors, and electrophotography. The device characteristics such as the light receiving member and the yield have been improved, and it has become possible to reduce the manufacturing cost of these electronic devices.

(3) While suppressing the occurrence of abnormal discharge that adversely affects the characteristics of the deposited film, active species having energy that effectively contributes to structural relaxation of the film during the formation of the deposited film are uniformly supplied over a large area. It is possible to reduce the damage to the surface of the deposited film by unnecessary ions and electrons that adversely affect the characteristics of the deposited film, and it is possible to uniformly form a deposited film having desired characteristics.

In the microwave plasma CVD method in which the source gas for depositing a deposited film is decomposed by microwave energy under a low pressure to form a deposited film on the substrate, an internal pressure of 50 mTo
A microwave energy smaller than the microwave energy required for 100% decomposition of the source gas at a vacuum degree of rr or less is applied to the source gas, and at the same time, an rf energy larger than the microwave energy to be applied is applied to the source gas. And a mesh made of a conductive metal is interposed between the substrate and the space in which the source gas is mainly decomposed by the applied microwave energy, and the mesh is kept at a temperature of 100 ° C. or higher during formation of the deposited film. The same effect as described above was obtained by using the deposited film forming method of the present invention, which is characterized by heating and holding the film.

In the microwave plasma CVD method of decomposing the source gas for depositing a deposited film with microwave energy under a low pressure to form a deposited film on the substrate, an internal pressure of 50 mTo
A microwave energy smaller than the microwave energy required for 100% decomposition of the source gas at a vacuum degree of rr or less is applied to the source gas, and at the same time, an rf energy larger than the microwave energy to be applied is applied to the source gas. A mesh made of a conductive metal is interposed between the substrate and the space where the source gas is mainly decomposed by the applied microwave energy, and an rf bias voltage is applied to the mesh. The same effect as above can be obtained by using the deposited film forming method of the present invention.

[0326]

[Brief description of drawings]

FIG. 1 is a schematic explanatory view of a film forming apparatus system suitable for applying a deposited film forming method of the present invention.

FIG. 2 is a schematic explanatory view showing a mode example of a photovoltaic element that is preferably formed by the deposited film forming method of the present invention.

FIG. 3 is a schematic explanatory view showing an example of a DC magnetron sputtering apparatus.

FIG. 4 is a schematic explanatory view showing an example of a resistance heating vacuum vapor deposition apparatus.

FIG. 5 is a schematic explanatory view of a film forming apparatus system suitable for applying the deposited film forming method of the present invention.

FIG. 6 is a graph showing the relationship between the preset temperature of the mesh and the photoelectric conversion efficiency when forming the i-type layer.

FIG. 7 is a graph showing the relationship between the set temperature of the mesh and the deterioration rate of the deposited film when forming the i-type layer.

FIG. 8 is a schematic explanatory view of a film forming apparatus system suitable for applying the deposited film forming method of the present invention.

[Explanation of symbols]

100 film forming apparatus 101 deposition chamber 102 dielectric window 103 gas introduction tube 104 substrate 105 heating heater 106 vacuum gauge 107 conductance valve 108 auxiliary valve 109 leak valve 110 waveguide 112 bias rod 113 mesh 114 mesh bias power supply 115 shutter 116 mesh Temperature controller 117 rf power supply 1020 for meshes Raw material gas supply devices 1041 to 1046 Introduction valves 1021 to 1026 Mass flow controllers 1031 to 1036 1 of mass flow controller
Next valves 1061 to 1066 Pressure regulators 1051 to 1056 Valves 1071 to 1076 Cylinders 200, 210 Photovoltaic elements 201, 211 Conductive substrates 202, 212 Light reflecting layers 203, 213 Reflection increasing layers 204, 214 Conductive layers 205, 215 218 i-type layer 206, 216, 217, 219 conductive type layer 207, 220 transparent electrode 208, 221 current collecting electrode 209, 222 irradiation light 301 deposition chamber 302 substrate 303 heating heater 304, 308 target 305, 309 insulating support 306, 310 DC power source 307, 311 Shutter 312 Vacuum gauge 313 Conductance valve 314, 315 Gas introduction valve 316, 317 Mass flow controller 401 Deposition chamber 402 Substrate 403 Heating heater 404 Deposition source 405 Heating heater 40 AC power 407 shutter 408 vacuum gauge 409 a conductance valve 410 gas introduction valve 411 mass flow controllers 412 leak valve 413 transmembrane pressure monitor

─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Masafumi Sano 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Ryo Hayashi 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Incorporated (72) Inventor Akira Sakai 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Yasushi Fujioka 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. ( 72) Inventor Shotaro Okabe 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Nao Yoshiri 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Invention Person Masahiro Kanai 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (56) Reference JP-A-2-277776 (JP, A) JP-A-1-191779 (JP, ) Patent flat 3-61370 (JP, A) JP flat 6-20971 (JP, A) (58 ) investigated the field (Int.Cl. ^7, DB name) C23C 16/00 - 16/56 H01L 21 / 205

Claims (3)

(57) [Claims] 1. A microwave plasma CVD method in which a raw material gas for forming a deposited film is decomposed by microwave energy under a low pressure to form a deposited film on a substrate, and the raw material gas is supplied at a vacuum degree of 50 mTorr or less in internal pressure.
Microwave energy smaller than that required for 0% decomposition is applied to the source gas, and at the same time, rf is larger than the applied microwave energy.
Energy is applied to the raw material gas, and a mesh made of a conductive metal is interposed between the substrate and the space where the raw material gas is mainly decomposed by the acting microwave energy, and a DC bias is applied to the mesh. A method for forming a deposited film by a microwave plasma CVD method, characterized in that a voltage is applied. 2. In a microwave plasma CVD method in which a raw material gas for forming a deposited film is decomposed by microwave energy under a low pressure to form a deposited film on a substrate, the raw material gas is 10 at a vacuum degree of 50 mTorr or less.
Microwave energy smaller than that required for 0% decomposition is applied to the source gas, and at the same time, rf is larger than the applied microwave energy.
Energy is applied to the raw material gas, and a mesh made of a conductive metal is interposed between the substrate and the space where the raw material gas is mainly decomposed by the microwave energy to act, and at the time of forming the deposited film. A method for forming a deposited film by a microwave plasma CVD method, which comprises heating and holding the mesh at a temperature of 100 ° C. or higher. 3. In a microwave plasma CVD method for decomposing a raw material gas for forming a deposited film with microwave energy under a low pressure to form a deposited film on a substrate, the raw material gas is 10 at a vacuum degree of 50 mTorr or less.
Microwave energy smaller than that required for 0% decomposition is applied to the source gas, and at the same time, rf is larger than the applied microwave energy.
Energy is applied to the raw material gas, and a mesh made of a conductive metal is interposed between the substrate and the space where the raw material gas is mainly decomposed by the microwave energy to act, and an rf bias is applied to the mesh. A method for forming a deposited film by a microwave plasma CVD method, characterized in that a voltage is applied.