JPS618914A - Glow discharge type film formation equipment - Google Patents

Abstract

PURPOSE:To simply make film formation speed equal if right and left semiconductor layers have different film formation speed by varying the capacity of a condenser connected in series to a separated electrode since this can greatly vary the film formation speeds of the right and the left semiconductor layers. CONSTITUTION:RF electrodes 1a, 1b are two metal plates placed in parallel on both sides of an insulation material 2 and each metal plate is connected in series to condensers which are adjusting means of RF, e.g., a fixed condenser 6b and a variable condenser 6a outside a reactor. On both sides of the RF electrodes 1a, 1b, a pair of grounded electrodes 3a, 3b are placed in parallel with the RF electrode surfaces and on the electrodes 3a, 3b, substrates 4a, 4b are placed. The RF electrodes are electrically divided in two and at least one of the RF electrodes is connected to the RF adjusting means in series. This enables to form a film on both sides of the RF electrodes 1a, 1b and even if film formation speeds on both sides are different, the film formation speeds can arbitrarily be adjusted by adjusting the RF adjusting means.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a glow discharge type film forming apparatus for forming a semiconductor film.

[Prior Art] Conventionally, a glow discharge type film forming apparatus used for manufacturing solar cells, etc. has a ground electrode (3) as shown in FIG.
On the substrate (4) placed above, RFj electrode (1), ground electrode (3), e-9-(5)
An apparatus based on the so-called parallel plate method, which allows more semiconductor layers to be deposited, is often used. Although the parallel plate method is suitable for forming a film over a large area, since discharge also occurs on the back side of the RF electrode (1) forming the electrode pair, a shield (7) is required to suppress this discharge. However, the provision of this shield has the disadvantage that the discharge becomes unstable.

A device shown in FIG. 5 has been devised as a device without a shield. In this case, the substrate (4a), (
4b), and heaters (5a) and (5b) if necessary.
Since the semiconductor film can be formed while heating the substrates (4a) and (4b), there is no need to provide a shield, and there is an advantage that the instability of discharge due to the provision of a shield is eliminated. However, if the formation speed of the left and right semiconductor layers is different, there is a drawback that the speed cannot be adjusted.

[Problems that the invention attempts to solve]
.

The present invention addresses the above-mentioned situation, namely, RF electric power.
This was done in order to solve the problem that the film formation speeds of the left and right semiconductor films are different, which occurs when a semiconductor film is formed by glow discharge decomposition on both sides of a single pole.

[Means for Solving the Problems] The present invention provides an apparatus for forming semiconductor films on substrates placed on both sides of an RF electrode by a glow discharge decomposition method. RF adjustment means connected in series to at least one of the RF electrodes, if the RFI1 node means is connected, via the RF adjustment means, or directly if the RFII node thickness means is not connected;
The present invention relates to a glow discharge type film forming apparatus characterized by comprising one matching circuit connected to each RF electrode, and a ground electrode provided to face each of the RF electrodes.

[Example] The apparatus of the present invention will be explained based on FIG. 1 showing one embodiment thereof.

The RF electrodes (1a) and (1b) are made by sandwiching two parallel metal plates with an insulating material (2) in between, and each metal plate has a capacitor, which is an RF node means, connected in series with the metal plate. For example, a fixed capacitor (6b) and a variable capacitor (6a) are connected outside the reactor. A coil may be used as the RF adjustment means instead of a capacitor. On the other hand, the RF supplied from the RF power supply
passes through a matching circuit, is divided into two parts, and is supplied to a capacitor.

On both sides of the RF electrodes (1a), (1b), ground electrodes (3a), (3b) serving as counter electrodes are arranged parallel to the RF electrode surface, and on top of these, substrates (4a), (4b) are placed. It will be placed. As shown in FIG. 1, heaters (5a) and (5b) are arranged as necessary, and substrates (4a) and (4b) are
may be heated.

As for the method of separating the RF electrodes (1a) and (1b), when introducing gas from inside the electrodes, it is preferable to use a structure in which an insulating material (2) is sandwiched around the electrodes, as shown in FIG. The method is not limited to this, and any method may be used as long as it is electrically insulated.

By electrically dividing the RF electrode into two in this way and connecting the RF adjustment means in series to at least one of the RF electrodes, it is possible to form a film on both sides of the RF electrodes (1a) and (1b). And even if the left and right film formation speeds are different, R
The film forming rate can be arbitrarily adjusted by adjusting the F adjusting means.

The distance between the RF electrodes separated by the insulating material (2) is arbitrary, but is usually 1 to 200 #l1lI. The distance between the RF electrode and the substrate is preferably about 5 to 50 #1 from the viewpoint of stability and uniformity of discharge, and more preferably about 10 to 30 m+.

The area of the RF electrode is preferably within 111, but if a larger area is required, the area of the RF electrode is divided into 1TIt or less.
A plurality of F electrodes may be arranged in a structure as shown in FIG. 2 for use. If necessary, the electrodes may be connected in a direct current manner in the longitudinal direction. When many electrode pairs are arranged in a straight line,
The film forming area can be increased, and theoretically it can be increased to infinity. Note that in the parallel plate method, the area of one electrode is limited to about 1 ml.

Substrate moving means (not shown) may be provided on both sides of the RF electrode to move the substrate parallel to the RF electrode. The substrate moving means may function only to transport the substrate to the RF electrode section and move the substrate after film formation. However, during film formation, the distance between the substrate and the RF electrode may be held substantially constant while the substrate may be moved in one direction or may be repeatedly moved in amplitude. By moving the substrate during film formation in this way, the thickness distribution of the formed film can be made extremely small. A specific example of such a substrate moving means is a multi-chamber in-line type device.

The RF electrode and the substrates carried on both sides thereof may be horizontal as long as they are approximately parallel to each other, may be vertical, or may be tilted at other angles; If the layers are arranged nearly vertically, there is no possibility that dust will fall onto the film-forming surface.
Using a long continuous substrate as one substrate,
In the case of continuous film formation, a method of moving the substrate to one side is suitable, but usually a short substrate is used.

In order to heat the substrate, the substrate may be heated by a heater provided as necessary.

Although the substrate temperature varies depending on the type of film to be formed and the purpose of use, it is usually preferably about 50 to 400°C.

As shown in FIG. 3, if 1 to 100 pairs of RF electrodes, preferably 1 to 10 pairs of RF electrodes arranged in a straight line are installed in parallel, it is possible to simultaneously form semiconductor layers on many substrates. This makes it possible to increase the film formation area.

There is no particular limitation on the film forming apparatus for forming an amorphous semiconductor film or the like in which the apparatus of the present invention is provided, and any commonly used type of film forming apparatus can be used. For example, the device may have a multi-chamber structure; in this case, at least one of the chambers constituting the multi-chamber structure (for example, the p-layer, one
The device of the present invention may be used in one of the rooms in which layers and n layers are formed. When using a device with a multi-chamber structure as described above, the partition walls are provided with slits and gate valves to allow the substrate to pass through each chamber. From the viewpoint of increasing productivity, it is preferable that a differential pumping chamber having a normal differential pumping means is provided so that the substrate can be continuously moved.

As mentioned above, the apparatus of the present invention as shown in FIG. 1 is installed as a glow discharge decomposition film forming apparatus for manufacturing amorphous semiconductor films, etc., and has a frequency of about 1 to 100 MHz, and a film formation rate per unit area of film formation. RF power is 0.003~0.2W/
cd, when performing microcrystallization, under the conditions of about 0.1 to 5 w/i, 0.01 to 0.01 to 0.01 to 500% of the raw material gas consisting of a reactive gas, such as a silicon compound, a carbon compound, a nitrogen compound, a doping gas, an inert gas, etc. Glow discharge is performed in the presence of about 5 Torr, and a semiconductor layer is formed on the substrate to a thickness of about 0.05 to 100 Torr.

When a film is formed using an apparatus such as the apparatus of the present invention, a film of uniform quality can be obtained, and since there is little parasitic discharge, it is difficult to generate powder, a film with few pinholes can be obtained, and it is easy to increase the area. It also has features such as extremely stable glow discharge and high RF usage efficiency. Additionally, silicon-containing pin, pn, hetero or homojunction solar cells, sensors, thin film trans
sister), CCD (charge couple)
Since plasma stability greatly affects the reproducibility of efficiency in devices such as d devices, especially solar cells containing amorphous silicon, the device of the present invention can achieve high conversion efficiency of 10% or more. can be obtained over a large area with good reproducibility.

Also, photosensitive materials for electrophotography, passivation films for LSI,
It is also suitably used for applications such as insulating films for printed circuit boards.

Next, the present invention will be explained based on examples.

Example 1 An example using a glow discharge type film forming apparatus similar to that shown in FIG. 1 will be described.

j Connect the capacitor to the RF electrode (560x 560an) sandwiching 4m of insulation material,
．． 2 through a 56MHz RF oscillator and matching circuit.
The split RF was introduced via a condenser. The capacitors used are fixed 250pF and Hax 500pF.
It was a variable capacitor. 400 square I as a substrate
Using TO/5002 glass substrate, substrate temperature 200℃
with SiH4/CHa = 50/50, B2H
s/(Sin< +CHa) = 0.05%(
100 people, Si
6000 people in the i layer consisting of tl 4, PH3/5iH
We trained 500 people in the n layer consisting of a = 0.2%. The capacitors used were 2509F and 35011F. Next, I attached AI to about 1000 mermaids and AM-1,1001W/c.
When we calculated the distribution of conversion efficiency of solar cells using d's solar simulator, the minimum was 10.4% and the maximum was 11.7.
%, an average of 11%, and it was found that extremely uniform and high efficiency could be obtained. Furthermore, even when the film formation rate was 10 people/SeC, the efficiency hardly changed.

Further, the thickness of the semiconductor layer was almost the same on the left and right sides and was uniform.

Example 2
-! The capacitor on the right side of Example 1 was fixed at 250 pF,
The deposition rate of the i-layer was determined in the same manner as in Example 1 except that the capacitor on the left side was changed to 10 to 5009 F. The results are shown in Table 1.

[Left below] [Effects of the invention] As described above, by changing the capacitance of the capacitor connected in series to the separated electrodes, the deposition rate of the left and right semiconductor layers can be greatly changed. If the deposition rates of the semiconductor layers are different, the deposition rates can be easily made the same by changing the capacitance of the capacitor.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of one embodiment of the device of the present invention, FIGS. 2 and 3 are explanatory diagrams of the electrode pair arrangement of different embodiments of the device of the present invention, and FIGS. 4 and 5 are conventional diagrams. FIG. 2 is an explanatory diagram regarding the film forming apparatus used. (Main symbols in the drawing) (1), (1a), (Ib): RF electrode (2): Insulator (3), (3a), (3b) Nigerland electrode (6a)
: Variable capacitor (6b): Fixed capacitor Figure 21 Country 2 Figure 3

Claims (1)

[Claims] 1. In an apparatus for forming a semiconductor film by a glow discharge decomposition method on a substrate placed on both sides of RF electrodes, at least one of the RF electrodes which are electrically insulated and arranged parallel to each other. RF adjustment means connected in series, connected to each RF electrode via the RF adjustment means when the RF adjustment means are connected, and directly when the RF adjustment means are not connected. A glow discharge type film forming apparatus comprising one matching circuit and a ground electrode provided to face each of the RF electrodes. 2. The film forming apparatus according to claim 1, wherein the RF adjustment means is a fixed or variable capacitor. 3. The film forming apparatus according to claim 1, wherein 1 to 100 pairs of electrodes each consisting of an RF electrode and a ground electrode are arranged in parallel. 4. The film forming apparatus according to claim 1, further comprising means for moving the substrate while maintaining a distance from the RF electrode. 5. The film forming apparatus according to claim 4, wherein the moving means is a repetitive amplitude moving means. 6. The film forming apparatus according to claim 4, wherein the moving means is a means for moving in one direction. 7 The frequency when performing the glow discharge is 1 to 10
Claim 1, which has an electrode pair with a frequency of 0 MHz;
The film forming apparatus according to item 2, 3, 4, 5, or 6. 8 Claims 1, 2, 3, and 4, wherein a heater is provided to heat the substrate.
The film forming apparatus according to item 5, 6, or 7. 9 Claims 1, 2, 3, 4, and 5, wherein the glow discharge type film forming apparatus has a multi-chamber structure.
The film forming apparatus according to item 6, 7, or 8. 10. Claims 1, 2, 3, 4, and 5, wherein the multi-chamber structure is partitioned by partition walls having slits, and the partitioned chambers have means for differentially evacuating the partitioned chambers. 6. The film forming apparatus according to item 6, 7, 8, or 9.