JP2002235173A - Plasma cvd apparatus and method for cleaning deposited film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a high throughput plasma CVD apparatus, with which the formation of foreign matters can be suppressed during depositing a film, and deposits formed on the inner wall, or the like, in a reaction chamber and causing a defective product when it is exfoliated, can be removed, and thereby the operation rate is increased. SOLUTION: The reaction chamber 1 has such a constitution that an upper chamber 2, an intermediate chamber 4 and a lower chamber 3 are provided, and these chambers are made electrically insulative with one another by insulating components 5 and 6, and further, the upper chamber 2 and the lower chamber 3 are grounded, and a high-frequency power can be impressed to the intermediate chamber 4. Thereby, the intermediate chamber 4 becomes a power electrode and the upper chamber 2 and the lower chamber 3 become earth electrodes, and further, uniform plasma is formed in the reaction chamber 1, and therefore, cleaning (etching) rate of the deposits on the wall can be enhanced. Accordingly, it becomes possible to realize the high throughput plasma CVD apparatus, with which the formation of foreign matters during depositing the film is suppressed, and deposits formed on the inner wall or the like in the reaction chamber can be effectively removed, and thereby, the operation rate is increased.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a CVD (chemical
For vapor deposition) equipment, in particular, in addition to the function of forming a film on a wafer or the like using microwave plasma and radio frequency (RF) plasma, a cleaning function of removing deposits formed on an inner wall surface of a reaction chamber during film formation. And a method for cleaning a deposited film.

[0002]

2. Description of the Related Art A plasma CV in which a film is formed on a wafer or the like using microwave plasma and radio frequency (RF) plasma.
Examples of the D device include, for example, an example described in JP-A-9-266096 and an example described in JP-A-2000-178741.

In the example described in Japanese Patent Application Laid-Open No. 9-266096, a reaction chamber is formed by being surrounded by an upper wall (or an opposing plate) and a peripheral wall which are electrically insulated from each other, and provided in the reaction chamber. In addition, a thin film can be formed on a substrate such as a wafer placed on a support table.

In the example described in Japanese Patent Application Laid-Open No. 2000-178741, a reaction chamber is formed by an upper chamber and a lower chamber which are electrically insulated from each other, and the upper chamber can be grounded during film formation. Meanwhile, high-frequency power is applied to the upper chamber so that the reaction chamber can be cleaned.

[0005]

The plasma C
In the process of growing a thin film on an object using a VD apparatus, a reaction product is deposited on an inner wall surface of a reaction chamber or a support base on which the object is arranged, and the thin film grows.

The deposited thin film is made of a thin film material (eg, S
iO ₂ , Si ₃ N ₄ , poly-Si, etc.), but growing to a certain thickness (several to several tens μm)
Cracks occur in the film due to the internal stress of the film itself, and the film is separated from the deposition wall surface.

[0007] The degree of this peeling greatly varies depending on the shape and material of the inner wall surface on which the thin film is deposited, and also the type of surface treatment therefor. In any case, when the deposit is peeled off, it adheres to the object as a foreign substance, and when the object is, for example, a silicon wafer, it causes disconnection or short circuit of the semiconductor circuit, resulting in a manufacturing defect. .

Therefore, before such a phenomenon occurs, the film deposited on the wall surface of the reaction chamber must be removed.

Therefore, the plasma CVD apparatus has a function of cleaning a deposited film in addition to a function of forming a film.

As a method of cleaning the deposited film, a method of activating a cleaning gas with plasma to remove the deposited film by a chemical reaction or a sputtering action, that is, a so-called plasma cleaning method is generally used. Regarding such a plasma cleaning method, Japanese Patent Application Laid-Open No.
The technique described in 66096 has one problem.

That is, in the above prior art, a high frequency voltage is applied to each of the upper wall and the support during the cleaning. However, in such a cleaning method, plasma is not generated in the entire reaction chamber, and the plasma is not generated. Since only strong plasma is generated on the wall and the support, there is a problem that the peripheral wall is not effectively cleaned.

[0012] This is thought to be due to the upper wall (or the opposing plate) being insulated from the peripheral wall. However, this is also a problem during film formation.

That is, since the upper wall is insulated from the peripheral wall and the ground of the upper wall is not grounded, it is difficult for the electric charge to escape, and electrons generated in the reaction chamber are accumulated on the upper wall, and this is abnormal discharge on the inner wall. This causes a problem that a large amount of foreign matter is generated at the time of film formation, which causes a reduction in the operation rate of the apparatus and defective production. In addition, the above-mentioned prior art, Japanese Patent Application Laid-Open
The technique described in Japanese Patent No. 78741 also has one problem.

That is, in this conventional technique, a high-frequency voltage is applied to the upper chamber divided into two during cleaning. In such a cleaning method, in particular, the entire upper chamber is cleaned by radicals generated by strong plasma formed near the insulating portion between the upper chamber and the lower chamber.

Therefore, when the volume of the reaction chamber, particularly the height of the upper chamber, increases, the cleaning rate of the upper surface of the upper chamber (the surface parallel to the wafer surface) is greatly reduced.

This is because, when the height of the upper chamber is increased, radicals generated by plasma formed near the insulating portions of the upper chamber and the lower chamber hardly reach the upper surface of the upper chamber.

An object of the present invention is to reduce the generation of foreign matter during film formation, and to effectively remove deposits which are generated on the inner wall surface of the reaction chamber and peeled off, thereby causing defective production. It is an object of the present invention to realize a high-throughput plasma CVD apparatus and a deposited film cleaning method capable of increasing the operation rate.

[0018]

The present invention has been made in view of the above-mentioned problems, and has assiduously studied a method of efficiently cleaning the entire wall surface of a reaction chamber of a plasma CVD apparatus. As a result, a high-frequency voltage applied to the reaction chamber was obtained. By adjusting the application site and the earth site, a uniform plasma can be generated in the entire reaction chamber, and the cleaning speed can be increased. That is, in order to achieve the above object, the present invention is configured as follows. (1) In a plasma CVD apparatus, a reaction chamber having an upper chamber, a middle chamber, and a lower chamber which are electrically insulated from each other; a substrate electrode arranged in the reaction chamber, on which an object to be processed is arranged; A microwave introduction unit that introduces a microwave into the reaction chamber; and a gas introduction unit that introduces a deposition gas into the reaction chamber when forming a film on the processing target, and introduces an etching gas into the reaction chamber when cleaning the deposited film. An exhaust unit for exhausting gas from the chamber, a first high-frequency power supply connected to the substrate electrode, and a second high-frequency power supply connected to the middle chamber.

(2) Preferably, in the above (1),
The upper chamber is grounded via a fixed or variable capacitor.

(3) Preferably, in the above (1), a capacitor and switching means for switching between grounding the upper chamber via the capacitor or grounding without the capacitor are provided. .

(4) In a plasma CVD apparatus, a reaction chamber having an upper chamber, a middle chamber, and a lower chamber which are electrically insulated from each other; a substrate electrode arranged in the reaction chamber, on which an object to be processed is arranged; A microwave introduction unit for introducing a microwave into the reaction chamber, and a gas introduction unit for introducing a film-forming gas into the reaction chamber when forming a film on an object to be processed and introducing an etching gas into the reaction chamber when cleaning the deposited film. And, a discharge unit for discharging gas from the reaction chamber, a high-frequency power supply, or connecting the high-frequency power supply to a substrate electrode,
A switching unit that selects whether to connect to the middle chamber, connects to the substrate electrode during the film formation, and connects to the middle chamber during the cleaning.

(5) Preferably, (1), (2),
In (3) or (4), the upper chamber, the middle chamber, and the lower chamber are electrically insulated from each other by an insulating component, and the material of the insulating component is alumina.

(6) In the method for cleaning a deposited film of a plasma CVD apparatus, the reaction chamber of the plasma CVD apparatus is divided into an upper chamber, a middle chamber, and a lower chamber which are electrically insulated from each other. Is grounded, an etching gas is introduced into the reaction chamber by a gas introduction unit, and a high-frequency voltage is applied from a high-frequency power supply to the middle chamber to clean a deposited film of a thin film material deposited in the reaction chamber.

(7) In the method for cleaning a deposited film of a plasma CVD apparatus, the reaction chamber of the plasma CVD apparatus is divided into an upper chamber, a middle chamber, and a lower chamber which are electrically insulated from each other, and the lower chamber is grounded. At the same time, the upper chamber is grounded via a variable capacitor, an etching gas is introduced into the reaction chamber by a gas introduction unit, a high frequency voltage is applied from a high frequency power supply to the middle chamber, and the upper chamber is deposited in the reaction chamber. Clean the deposited film of thin film material.

(8) a polysilicon film for the gate electrode wiring,
In a semiconductor element having at least one of a phosphorus-doped polysilicon film, an oxide film or a phosphorus glass film for interlayer insulation, and a Si ₃ N ₄ film for capacitor insulation, at least one of the films is A reaction chamber having an upper chamber, a middle chamber, and a lower chamber that are electrically insulated from each other; a first high-frequency power supply disposed in the reaction chamber and connected to a substrate electrode on which an object to be processed is disposed; C having a second high frequency power supply connected to
The film is formed using a VD device.

In the present invention, the reaction chamber is composed of an upper chamber, a middle chamber, and a lower chamber, and is electrically insulated from each other by insulating parts. Is applied.

By doing so, the middle chamber becomes a power electrode and the upper and lower chambers become earth electrodes, uniform plasma is formed in the reaction chamber, and the cleaning (etching) rate of wall surface deposits is improved.

As the material of the insulating component, a material having high resistance to fluorine radicals such as alumina (Al ₂ O ₃ ) is preferable. By doing so, it becomes possible to reduce the frequency of replacement of the insulating parts and reduce foreign matter.

Further, the upper chamber is grounded via a fixed capacity type or variable capacity type capacitor. By doing so, the plasma shape in the reaction chamber can be changed, and the distribution of the cleaning rate on the wall surface of the reaction chamber can be controlled.

Further, a switch is provided in the upper chamber for switching the grounding mode of the upper chamber, and control is performed so as to form a plasma shape according to the deposition distribution on the wall surface of the reaction chamber.

Further, in order to reduce the number of components of the CVD apparatus, one high-frequency power source is used by switching the application site by a switch at the time of cleaning and at the time of film formation.

[0032]

Embodiments of the present invention will be described below with reference to the drawings.

(First Embodiment) FIGS. 1 to 4 and 8 show a plasma CVD apparatus according to a first embodiment of the present invention.
This will be described with reference to FIG.

FIG. 1, FIG. 2 and FIG. 8 are longitudinal sectional views showing a schematic longitudinal sectional structure of the reaction chamber 1 in the plasma CVD apparatus. As shown in FIG. 1, the plasma CVD apparatus includes a reaction chamber 1, a substrate electrode 14 serving as a support, a microwave introduction window (made of quartz, etc.) 7 for introducing microwaves into the reaction chamber 1, Microwave oscillator 21 and vacuum pump 11
A gas abatement apparatus 12, an upper nozzle 8 for introducing a film forming or cleaning gas into the reaction chamber 1, and a lower nozzle 9
And high frequency power supplies (frequency 13.56 MHz) 16, 20
And

The reaction chamber 1 is formed by combining the upper chamber 2, the middle chamber 4, and the lower chamber 3, that is, the upper chamber 2, the middle chamber 4, and the lower chamber 3 are divided. A reaction chamber 1 is formed by being surrounded by the chambers 2, 3, and 4.

Each of the chambers 2, 3, and 4 has a conductive (for example, aluminum) chamber configuration. Also, upper chamber 2,
The middle chamber 4 and the lower chamber 3 are electrically insulated from each other by interposing insulating parts 5 and 6 made of alumina or the like on their combined surfaces.

The middle chamber 4 has a plurality of upper nozzles 8 made of alumina (Al ₂ O ₃ ) for introducing a film forming gas such as oxygen, and a microwave introduction window (made of quartz or the like) 7. There are several places.

A waveguide 23 for guiding microwaves is connected to the window 7, and a microwave oscillator 21 (frequency: 2.45 GHz) for generating microwaves and a microwave power supply 22 are attached beyond the waveguide 23. Have been. Further, a high frequency power supply 16 is connected via a matching box 15.

On the outer surface of the reaction chamber 1, an ECR (Electron Cyclotron Resonance) is provided near the exit of the microwave introduction window 7.
A permanent magnet (shown in the drawing) for forming a region to increase the electron density, promote the generation of ions and radicals, generate a high-density plasma, and confine the plasma generated in the reaction chamber 1 to a magnetic field. ) Are arranged.

A vacuum pump 11 is attached to the lower part of the lower chamber 3. A gas abatement device 12 is connected downstream of the vacuum pump 11.

The lower chamber 3 is grounded by a ground wire 18, and the upper chamber 2 is grounded by a ground wire 17.

An insulating part 6 for insulating the middle chamber 4 and the lower chamber 3 from each other includes a lower nozzle 9 made of alumina (Al ₂ O ₃ ) for introducing a film forming gas such as SiH ₄ or Ar. Are provided in the circumferential direction of the chambers 3 and 4.

The substrate electrode 14 incorporates an electrostatic attraction device 10 for attracting the wafer 13 for film formation. A matching box 19 and a high-frequency power supply 20 are connected to the electrostatic attraction device 10 so that a high-frequency voltage can be applied.

The wafer 13 during film formation is heated not only by heat input from plasma but also by the incidence of ions and heat of reaction. Since the temperature of the wafer 13 greatly affects the film quality, the film formation rate, and the like, the temperature of the wafer 13 needs to be controlled. This control is performed by the pressure of the helium (He) gas flowing in the gap between the wafer 13 and the electrostatic chuck 14.

In the plasma CVD apparatus according to the first embodiment of the present invention, after a plurality of film forming processes of the wafer 13 → cleaning → precoat → film forming → cleaning
Repeat the process. When the film forming process is repeated a plurality of times, a film of the reaction by-product is gradually deposited on the inner wall surface of the reaction chamber 1 and the surface of the substrate electrode 14.

When the deposited film exceeds a certain thickness, a crack is generated in the deposited film due to the internal stress of the deposited film itself. It adheres to the surface and causes a short circuit or disconnection of the semiconductor element wiring, resulting in poor manufacturing and lowering production efficiency.

Therefore, before such a phenomenon occurs,
Cleaning for removing the deposited film in the reaction chamber 1 is performed, and subsequently, pre-coating for preventing the occurrence of foreign substances due to cleaning is performed.

Hereinafter, each specific method will be described.

(1) Film Forming Method A film forming method in the above-mentioned plasma CVD apparatus will be described with reference to FIG. First, the wafer 13 is introduced into the reaction chamber 1 whose pressure has been adjusted by the vacuum pump 11 via the transfer chamber (not shown), placed on the substrate electrode 14, and a voltage is applied to the electrostatic suction device 10. By applying the voltage, the wafer 13 is attracted by electrostatic force.

In this state, for example, oxygen gas is supplied from the upper nozzle 8 and Ar gas and SiH ₄ gas are supplied from the lower nozzle 9 by a desired amount using a mass flow controller (not shown).
It is introduced into the reaction chamber 1 and the pressure inside the reaction chamber 1 is adjusted from several millimeters to several tens Pa using the vacuum pump 11.

When microwaves of several hundreds to several kW are introduced from the microwave introduction window 7 in this manner, a large amount of electrons generated in the ECR region turn O ₂ , Ar, and SiH ₄ into plasma, thereby generating The SiH ₃ , which is a decomposition product of the obtained SiH ₄ , reacts with oxygen or the like on the surface of the wafer 13, whereby an SiO ₂ film is deposited on the wafer 13.

Simultaneously, when a high frequency power of several hundreds to several kW is applied to the substrate electrode 14 using the high frequency power supply 20 and the matching box 19, a plasma sheath is formed between the surface of the wafer 13 and the plasma. Then, since a bias voltage (several tens to thousands of volts) is generated, ions (especially Ar) generated by turning the introduced gas into plasma are incident on the surface of the wafer 13 by an electric field.

As a result, the SiO ₂ film deposited on the surface of the wafer 13 is sputtered with Ar or oxygen ions. By doing so, SiO _{2 can be formed at} a step portion such as an Al wiring.
The film can be formed without voids (voids).

After the desired film thickness is deposited, the introduction of the gas, the application of the microwave, and the application of the high-frequency voltage are stopped, and then the applied voltage of the electrostatic attraction device 10 is turned off. The wafer 13 is carried out of the chamber 1.

(2) Cleaning Method Next, a cleaning method will be described with reference to FIG. First, an electrostatic adsorption device 1 is placed in a reaction chamber 1 whose pressure is adjusted by a vacuum pump 11 via a transfer chamber (not shown).
A cover wafer 24 made of alumina or the like for protecting the surface of the substrate 0 from plasma is introduced and placed on the substrate electrode 14.

In this manner, a desired amount of NF ₃ gas is introduced into the reaction chamber 1 from the upper nozzle 8 using a mass flow controller (not shown), and several to several thousand Pa The NF ₃ plasma is generated in the reaction chamber 1 by adjusting the pressure in the reaction chamber 1 and applying a high-frequency power of several hundreds to several kW using the high-frequency power supply 16 and the matching box 15 to the middle chamber 4. I do.

Then, F radicals and F ions generated by the decomposition of NF ₃ gas are deposited on the SiO 2
_{The two} films react with Si and are converted into a gas such as SiF ₄ and discharged to clean (etch) the deposited film on the wall surface. FIGS. 3 and 4 show experimental results of the etching rate ratio distribution between the upper chamber 2 and the middle chamber 4 in the first embodiment at the time of cleaning. The etching rate ratio is obtained by dividing the etching rate of each measuring device by the value of the center of the upper chamber 2 (radial position 0 mm). The vertical axis in FIG. 3 indicates the etching rate ratio, and the horizontal axis indicates the radial position. The vertical axis in FIG. 4 indicates the etching rate ratio, and the horizontal axis indicates the chamber height.

FIGS. 3 and 4 show that the etching rate ratio is in the range of 0.5 at the minimum and 2.0 at the maximum.

According to the first embodiment of the present invention, high frequency power is applied to the middle chamber 4 to ground the upper chamber 2 and the lower chamber 3. Therefore, the middle chamber 4 serves as a power electrode, and the upper chamber 2 and the lower chamber 3 serve as earth electrodes, so that substantially uniform plasma is generated in the reaction chamber 1. That is, it became possible to set it within the range of 0. As described above, according to the first embodiment, since the deposited film on the inner wall surface of the reaction chamber 1 can be cleaned substantially uniformly, there is little cleaning damage on the inner wall surface of the reaction chamber 1 and the effect that cleaning can be performed in a short time. is there. In order to confirm the effect of the first embodiment of the present invention, an etching rate according to the related art was measured. FIG. 8 shows the configuration of an experimental apparatus corresponding to the prior art. In the configuration shown in FIG. 8, the upper chamber 2 and the middle chamber 4
Instead of the insulating component 5 as in the present invention, a conductive component 25 made of aluminum or the like was inserted, and a high-frequency voltage was applied to the middle chamber 4 using the high-frequency power supply 16 and the matching box 15.

FIGS. 9 and 10 show experimental results of the etching rate ratio distribution in the conventional plasma CVD apparatus shown in FIG. 8, and FIG. 9 shows the etching rate ratio of the upper chamber. FIG. 10 shows the etching rate ratio of the middle chamber.

From FIGS. 9 and 10, it can be seen that the etching rate ratio of the upper chamber 2 is almost 1 while the etching rate of the middle chamber 4 is from a minimum of around 3 to a maximum of 1.
It can be seen that there is a large distribution of 5. As shown in FIG. 10, the large rate ratio near the lower end (chamber height 0 mm) of the middle chamber 4 is strong only in the vicinity of the insulating component 6 between the middle chamber 4 and the lower chamber 3 in the related art. This is because plasma is generated and uniform plasma is not generated in the entire reaction chamber 1. As described above, in the conventional technique, the deposited film on the inner wall surface of the reaction chamber 1 cannot be uniformly cleaned, so that the cleaning damage on the inner wall surface of the reaction chamber 1 is large, and the cleaning time until the cleaning is completed is prolonged.

(3) Precoating Method The deposited film deposited on the inner wall surface of the reaction chamber 1 is removed by the above-described cleaning method. At this time, since the deposition distribution of the deposited film and the etching distribution of the deposited film by the cleaning do not always coincide with each other, if the deposit on the inner wall surface of the reaction chamber 1 is entirely removed, the wall surface itself is removed in the portion where the film was removed in the initial stage. In other words, so-called overetching occurs.

Therefore, there are the following problems (1) and (2) in the film formation immediately after the completion of the cleaning.

(1) Since the inner wall surface of the reaction chamber 1 is rough and reaction products and gas adsorption due to cleaning remain on the inner wall surface,
Foreign substances frequently occur due to film peeling or the like.

(2) Since a conductive wall surface is exposed immediately after cleaning, when a large amount of electrons generated by the plasma are accumulated in the insulating film on the wall surface of the reaction chamber 1, the conductive wall surface and the insulating film may The dielectric breakdown of the deposited film occurs due to the potential difference between them, and foreign substances frequently occur.

In order to prevent the above problems (1) and (2), the inner wall surface of the reaction chamber 1 is pre-coated immediately after cleaning.

The precoating method will be described with reference to FIG. First, the wafer 13 is introduced into the reaction chamber 1 whose pressure has been adjusted by the vacuum pump 11 via the transfer chamber (not shown), and is set on the substrate electrode 14. By applying the voltage, the wafer 13 is
To adsorb.

In this state, for example, oxygen gas is introduced from the upper nozzle 8 and Ar and SiH ₄ gas are introduced from the lower nozzle 9 into the reaction chamber 1 by using a mass flow controller (not shown). From several millimeters to tens of Pa using
Then, the pressure in the reaction chamber 1 is adjusted.

In this way, when a few hundred to several Kw μ-waves are introduced from the microwave introduction window 7, a large number of electrons generated in the ECR region turn O ₂ , Ar, and SiH ₄ into plasma, thereby generating Si is a decomposition product of SiH ₄ which is
By reacting H ₃ with oxygen or the like, an SiO ₃ film is deposited on the inner wall surface of the reaction chamber 1.

After depositing a SiO ₃ film having a desired thickness,
After stopping the gas introduction and microwave application, the applied voltage of the electrostatic suction device 10 is turned off, and the wafer 13 is moved into the reaction chamber 1.
Take it out.

As described above, the above problem (1),
(2) can be prevented from occurring.

As described above, according to the first embodiment of the present invention, the reaction chamber 1 includes the upper chamber 2 and the middle chamber 4
And a lower chamber 3, wherein the insulating parts 5 and 6 are electrically insulated from each other, and the high frequency power is applied to the middle chamber 4 by grounding the upper chamber 2 and the lower chamber 3. Is done.

With this configuration, the middle chamber 3
Is a power electrode, the upper and lower chambers 2 and 3 are ground electrodes, uniform plasma is formed in the reaction chamber 1, and the cleaning (etching) rate of wall deposits is improved.

Therefore, the generation of foreign matter during film formation is small,
In addition, a high-throughput plasma CVD apparatus and a deposition film capable of effectively removing deposits generated on the inner wall surface of the reaction chamber and causing the production failure by peeling off the deposits and increasing the operation rate. A cleaning method can be realized.

(Second Embodiment) A plasma CVD apparatus according to a second embodiment of the present invention will be described with reference to FIG. FIG. 5 is a schematic longitudinal sectional view of the reaction chamber 1 in the plasma CVD apparatus.

As shown in FIG. 5, in the second embodiment of the present invention, the upper chamber 2 is grounded via a variable capacitor 26. Other configurations are the same as those of the first embodiment.

The film forming method, pre-coating method, and overall processing flow in the plasma CVD apparatus according to the second embodiment of the present invention are the same as those in the first embodiment.

Next, a cleaning method according to the second embodiment of the present invention will be described with reference to FIG. First, a cover wafer 24 made of alumina or the like for protecting the surface of the electrostatic adsorption device 10 from plasma is introduced into the reaction chamber 1 whose pressure has been adjusted by the vacuum pump 11 via a transfer chamber (not shown). And placed on the substrate electrode 14.

In this way, a desired amount of NF ₃ gas is introduced into the reaction chamber 1 from the upper nozzle 8 by using a mass flow controller (not shown), and the pressure is increased from several to several thousands Pa by using the vacuum pump 11. The pressure in the reaction chamber 1 is adjusted. Further, the variable capacitor 26 is set to a predetermined value, and the high frequency power supply 16 and the matching box 1 are set in the middle chamber 4.
The NF ₃ plasma is generated in the reaction chamber 1 by applying a high frequency power of several hundreds to several kW using the device 5.

F radical generated by decomposition of NF ₃ gas,
F ions are deposited on the wall surface of the reaction chamber 1 in the SiO ₂ film.
The deposited film on the wall surface is cleaned (etched) by reacting with i and forming a gas such as SiF ₄ and discharging the gas. According to the second embodiment of the present invention, high frequency power is applied to the middle chamber 4, the upper chamber 2 is grounded via the variable capacitor 26, and the lower chamber 3 is directly grounded. Thereby, the middle chamber 4 becomes a power electrode,
The upper chamber 2 and the lower chamber 3 serve as earth electrodes, and NF ₃ plasma is generated in the reaction chamber 1. In this case, by adjusting the variable capacitance type condenser 26 of the upper chamber 2 in advance according to the conditions in the reaction chamber 1, the NF that can be cleaned according to the deposition distribution of the deposited film on the wall surface in the reaction chamber 1.
₃ Plasma can be formed in the reaction chamber 1. As described above, according to the second embodiment of the present invention, since the cleaning can be performed substantially uniformly according to the deposited film distribution on the inner wall surface of the reaction chamber 1, the cleaning damage on the inner wall surface of the reaction chamber 1 is small, and There is an effect that cleaning can be performed in a short time.

That is, according to the second embodiment of the present invention, the same effect as that of the first embodiment can be obtained, and the variable capacitor 2 provided in the upper chamber 2 can be obtained.
By adjusting 6, the cleaning can be performed with high efficiency according to the deposited film distribution.

(Third Embodiment) A plasma CVD apparatus according to a third embodiment of the present invention will be described with reference to FIG. FIG. 6 is a schematic vertical sectional view of a reaction chamber 1 in a plasma CVD apparatus according to a third embodiment of the present invention.

As shown in FIG. 6, in the third embodiment,
The upper chamber 2 is configured to be grounded via the variable capacitance type capacitor 26 using the switch 27, or to be directly grounded without using the variable capacitance type capacitor. Other configurations are the same as those of the first embodiment.

The film forming method, pre-coating method, and overall processing flow in the plasma CVD apparatus according to the third embodiment of the present invention are the same as those in the first embodiment.

A cleaning method according to the third embodiment of the present invention will be described with reference to FIG. First, via a transfer chamber (not shown), a cover wafer 2 made of alumina or the like for protecting the surface of the electrostatic adsorption device 10 from plasma is placed in the reaction chamber 1 pressure-adjusted by the vacuum pump 11.
4 is introduced and placed on the substrate electrode 14.

In this way, a desired amount of NF ₃ gas is introduced into the reaction chamber 1 from the upper nozzle 8 by using a mass flow controller (not shown), and the pressure is increased from several to several thousand Pa by using the vacuum pump 11. The pressure in the reaction chamber 1 is adjusted.

Further, whether the upper chamber 2 is grounded via the variable capacitor 26 or directly is set by the switch 27, and the upper chamber 2 is grounded using the high frequency power supply 16 and the matching box 15 in the middle chamber 4. By applying a high frequency power of one hundred to several Kw, NF ₃ plasma is generated in the reaction chamber 1.

F radical generated by decomposition of NF ₃ gas,
F ions are deposited on the wall surface of the reaction chamber 1 in the SiO ₂ film.
The deposited film on the wall surface is cleaned (etched) by reacting with i and forming a gas such as SiF ₄ and discharging the gas. According to the third embodiment of the present invention, high-frequency power is applied to the middle chamber 4, and the upper chamber 2 is grounded via the variable capacitor 26 by the switch 27, or not via the capacitor 26. Whether it is directly grounded is selected depending on the cleaning conditions, and the lower chamber 3 is directly grounded.

Thus, the middle chamber 4 serves as a power electrode, and the upper chamber 2 and the lower chamber 3 serve as earth electrodes, and NF ₃ plasma is generated in the reaction chamber 1. In this case, by adjusting the switch 27 of the upper chamber 2, NF ₃ plasma that can be cleaned in accordance with the deposition distribution of the deposited film on the inner wall surface of the reaction chamber 1 can be formed in the reaction chamber 1. As described above, according to the third embodiment of the present invention, it is possible to substantially uniformly clean the inner wall surface of the reaction chamber 1 in accordance with the distribution of the deposited film on the inner wall surface. There is an effect that cleaning can be performed in a short time. (Fourth Embodiment) A plasma CVD apparatus according to a fourth embodiment of the present invention will be described with reference to FIG. FIG. 7 is a schematic vertical sectional view of a reaction chamber 1 in a plasma CVD apparatus according to a fourth embodiment of the present invention.

As shown in FIG. 7, in the fourth embodiment of the present invention, the matching box 19 and the high-frequency power supply 20 can be switched and connected to the substrate electrode 14 and the middle chamber 4 by the switch 28. I have. The other configuration is the same as the example of FIG. 1 except that the matching box 15 and the high-frequency power supply 16 are omitted from the example of FIG.

The plasma C according to the fourth embodiment of the present invention
The film forming method, pre-coating method, and overall processing flow in the VD apparatus are the same as those in the first embodiment.

The cleaning method will be described with reference to FIG. First, a cover wafer 24 made of alumina or the like for protecting the surface of the electrostatic adsorption device 10 from plasma is introduced into the reaction chamber 1 whose pressure has been adjusted by the vacuum pump 11 via a transfer chamber (not shown). And placed on the substrate electrode 14.

In this way, a desired amount of NF ₃ gas is introduced into the reaction chamber 1 from the upper nozzle 8 by using a mass flow controller (not shown), and the pressure is increased from several to several thousands Pa by using the vacuum pump 11. The pressure in the reaction chamber 1 is adjusted.

Further, the high frequency power supply 20 and the matching box 19 connected to the substrate electrode 14 at the time of film formation are switched and connected to the middle chamber 4 side by the switch 28 so that the high frequency power of several hundreds to several Kw is supplied to the middle chamber 4. 4 to generate NF ₃ plasma in the reaction chamber 1.

F radical generated by decomposition of NF ₃ gas,
F ions are deposited on the inner wall surface of the reaction chamber 1 in the S _{2 of} the SiO ₂ film.
The deposited film on the wall surface is cleaned (etched) by reacting with i and forming a gas such as SiF ₄ and discharging the gas. As described above, according to the fourth embodiment of the present invention, the same effects as those of the first embodiment can be obtained. 20 and the matching box 19 can be realized by switching and connecting to the substrate electrode 14 and the middle chamber 4, so that there is an effect that the device components can be reduced and the device cost can be reduced.

A semiconductor element is an example of an object to be processed formed by the plasma CVD apparatus according to the above-described embodiment. In this semiconductor device,
At least one of a polysilicon film of a gate electrode wiring, a phosphorus-doped polysilicon film, an oxide film or a phosphorus glass film for interlayer insulation, and a Si ₃ N ₄ film for capacitor insulation is formed by the plasma CVD apparatus. Filmed.

In the above example, the upper chamber 2 is directly grounded or is grounded via a variable capacitor. However, even if the upper chamber is not grounded, the upper chamber 2 is connected to the upper chamber. Compared to the prior art in which the middle chamber and the conductive member were electrically connected by a conductive member,
There is an effect that the cleaning (etching) rate of the wall surface deposit is improved.

In the above-described embodiment, the upper chamber 2 is configured to be grounded via the variable capacitance type capacitor. However, the upper chamber 2 is configured to be grounded via the fixed capacitance type capacitor instead of the variable capacitance type capacitor. Can also obtain the same effect as described above.

[0099]

According to the present invention, in a plasma CVD apparatus, a reaction chamber is divided into an upper chamber, a middle chamber, and a lower chamber, and the upper, middle, and lower chambers are electrically insulated from each other by an insulating member. With the structure, the upper chamber and the lower chamber are grounded, and high-frequency power is applied to the middle chamber.

With such a configuration, the middle chamber serves as the power electrode, and the upper and lower chambers serve as the ground electrode, uniform plasma is formed in the reaction chamber, and the cleaning (etching) rate of wall surface deposits is improved.

Therefore, the generation of foreign matter during film formation is small,
In addition, a high-throughput plasma CVD apparatus and a deposition film capable of effectively removing deposits generated on the inner wall surface of the reaction chamber and causing the production failure by peeling off the deposits and increasing the operation rate. A cleaning method can be realized.

[Brief description of the drawings]

FIG. 1 is a plasma CVD according to a first embodiment of the present invention.
FIG. 3 is a schematic vertical sectional view of a reaction chamber during a film forming process of the apparatus.

FIG. 2 is a schematic longitudinal sectional view of a reaction chamber during cleaning of the plasma CVD apparatus according to the first embodiment.

FIG. 3 is an explanatory diagram of an etching rate ratio distribution in an upper chamber during cleaning of the plasma CVD apparatus according to the first embodiment.

FIG. 4 is an explanatory diagram of an etching rate ratio distribution in a middle chamber during cleaning of the plasma CVD apparatus according to the first embodiment.

FIG. 5 shows a plasma CVD according to a second embodiment of the present invention.
FIG. 3 is a schematic vertical sectional view of a reaction chamber at the time of cleaning the apparatus.

FIG. 6 shows a plasma CVD according to a third embodiment of the present invention.
FIG. 3 is a schematic vertical sectional view of a reaction chamber at the time of cleaning the apparatus.

FIG. 7 shows a plasma CVD according to a fourth embodiment of the present invention.
FIG. 3 is a schematic vertical sectional view of a reaction chamber at the time of cleaning the apparatus.

FIG. 8 is a schematic longitudinal sectional view of a reaction chamber at the time of cleaning of a conventional plasma CVD apparatus.

FIG. 9 is an explanatory diagram of an etching rate ratio distribution of an upper chamber during cleaning of a conventional plasma CVD apparatus.

FIG. 10 is an explanatory diagram of an etching rate ratio distribution in a middle chamber during cleaning of a conventional plasma CVD apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Reaction chamber 2 Upper chamber 3 Lower chamber 4 Middle chamber 5, 6 Insulating parts 7 Microwave introduction window 8 Upper nozzle 9 Lower nozzle 10 Electrostatic adsorption device 11 Vacuum pump 12 Gas elimination device 13 Wafer 14 Substrate electrode 15, 19 Matching Box 16 High-frequency power supply 17, 18 Earth wire 20 High-frequency power supply 21 Microwave oscillator 22 Microwave power supply 23 Waveguide 24 Cover wafer 26 Variable capacitor 27, 28 Switch

 ──────────────────────────────────────────────────続 き Continued on front page (72) Inventor Shingo Yokoyama 502 Kandate-cho, Tsuchiura-shi, Ibaraki Machinery Research Laboratory, Hitachi, Ltd. (72) Inventor Eiji Setoyama 1-1-1, Kokubuncho, Hitachi-shi, Ibaraki Stock (72) Inventor Yuichiro Ueno 7-2-1, Omika-cho, Hitachi City, Ibaraki Prefecture Inside Power and Electricity Research Laboratory, Hitachi, Ltd. (72) Inventor Naonori Wada Hitachi, Ibaraki Prefecture 7-2-1 Omikacho Hitachi Electric Power & Electric Development Laboratory Co., Ltd. (72) Inventor Koji Ishiguro 1-1-1 Kokubuncho, Hitachi City, Ibaraki Prefecture F-term, Semiconductor Manufacturing Equipment Promotion Division, Hitachi, Ltd. (Reference) 4G075 AA24 BC04 BC06 BD14 CA47 4K030 AA06 AA16 BA29 BA40 BA42 BA44 BB04 DA06 FA02 KA08 LA02 LA15 5F 045 AA09 AC02 BB08 BB15 DP04 EB02 EB06 EC01 EF01 EF08 EH04

Claims (8)

[Claims] A reaction chamber having an upper chamber, a middle chamber, and a lower chamber which are electrically insulated from each other; a substrate electrode arranged in the reaction chamber, on which an object to be processed is arranged; and a microwave in the reaction chamber. A gas introduction unit for introducing a film-forming gas into the reaction chamber when forming a film on the object to be processed, and an etching gas for introducing an etching gas into the reaction chamber when cleaning the deposited film; A plasma CVD apparatus comprising: a discharge unit for discharging gas; a first high-frequency power supply connected to a substrate electrode; and a second high-frequency power supply connected to a middle chamber. 2. The plasma CVD apparatus according to claim 1, wherein said upper chamber is grounded via a fixed-capacity or variable-capacitance capacitor.
VD device. 3. The plasma CVD apparatus according to claim 1, further comprising: a capacitor; and switching means for switching between grounding the upper chamber via the capacitor and grounding without passing through the capacitor. Characteristic plasma CVD apparatus. 4. A reaction chamber having an upper chamber, a middle chamber, and a lower chamber which are electrically insulated from each other, a substrate electrode disposed in the reaction chamber, on which an object to be processed is disposed, and a microwave in the reaction chamber. A gas introduction unit for introducing a film-forming gas into the reaction chamber when forming a film on the object to be processed, and an etching gas for introducing an etching gas into the reaction chamber when cleaning the deposited film; A discharge unit for discharging gas, a high-frequency power supply, and a selection of whether to connect the high-frequency power supply to the substrate electrode or to the middle chamber, to connect to the substrate electrode during the film formation, and to the middle chamber during the cleaning. And a switch connected to the plasma CVD apparatus. 5. The plasma CVD apparatus according to claim 1, wherein the upper chamber, the middle chamber, and the lower chamber are electrically insulated from each other by an insulating part. A plasma CVD apparatus, wherein the material of the insulating component is alumina. 6. A method for cleaning a deposited film of a plasma CVD apparatus, comprising: dividing a reaction chamber of the plasma CVD apparatus into an upper chamber, a middle chamber, and a lower chamber which are electrically insulated from each other; Grounding, introducing an etching gas into the reaction chamber by a gas introduction unit, applying a high-frequency voltage from a high-frequency power supply to the middle chamber, and cleaning a deposited film of a thin film material deposited in the reaction chamber. To clean the deposited film. 7. A method of cleaning a deposited film of a plasma CVD apparatus, comprising: dividing a reaction chamber of the plasma CVD apparatus into an upper chamber, a middle chamber, and a lower chamber that are electrically insulated from each other, and grounding the lower chamber. The upper chamber is grounded via a variable capacitor, an etching gas is introduced into the reaction chamber by a gas introduction unit, a high frequency voltage is applied from a high frequency power supply to the middle chamber, and a thin film deposited in the reaction chamber is formed. A method for cleaning a deposited film, comprising cleaning a deposited film of a material. 8. A semiconductor device comprising at least one of a polysilicon film for a gate electrode wiring, a phosphorus-doped polysilicon film, an oxide film or a phosphorus glass film for interlayer insulation, and a Si ₃ N ₄ film for capacitor insulation. In a semiconductor device, a reaction chamber having an upper chamber, a middle chamber, and a lower chamber in which at least one of the films is electrically insulated from each other, and a substrate electrode disposed in the reaction chamber and on which an object to be processed is disposed A semiconductor device formed by using a plasma CVD apparatus having a first high-frequency power supply connected to the first chamber and a second high-frequency power supply connected to the middle chamber.