JP3224011B2 - Plasma-excited chemical vapor deposition apparatus and plasma etching apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a plasma-excited chemical vapor deposition apparatus and a plasma etching apparatus, and more particularly to a semiconductor such as a hydrogenated amorphous silicon (hereinafter abbreviated as a-Si: H) thin film and a silicon crystalline thin film. The present invention relates to an apparatus for forming a film, an insulating film, and the like by chemical vapor deposition (hereinafter, also referred to as plasma CVD) using high-frequency plasma, and an apparatus for etching these semiconductor films and insulating films using high-frequency plasma.

[0002]

2. Description of the Related Art FIG. 6 is a view for explaining a conventional parallel plate type high frequency plasma CVD apparatus. FIG. 6 (a) shows a schematic configuration of a reaction vessel of the apparatus, and FIG. 2 shows a planar shape of a cathode electrode provided in the reaction vessel.

In FIG. 1, reference numeral 200 denotes a plasma CVD apparatus which has a reaction vessel 4 for performing chemical vapor deposition using high-frequency plasma, and forms a semiconductor film and an insulating film in the reaction vessel 4. An anode electrode 2 on which a member to be processed 3 such as a semiconductor substrate is mounted is provided in the reaction vessel 4, and a cathode electrode 1 is provided so as to face the anode electrode 2. The anode electrode 2 is grounded, and a high-frequency voltage for exciting plasma is applied to the cathode electrode 1. A gas inlet 5 for introducing a material gas into the reaction vessel 4 is formed in a portion of the reaction vessel 4 facing the center of the cathode electrode. The high frequency power applied to the cathode electrode 1 is also introduced.

Next, a film forming process using a plasma CVD apparatus having such a configuration will be described. When a material gas is supplied into the reaction vessel 4 and high-frequency power is supplied to the cathode electrode 1, a high-frequency electric field generated in a space 200a between the cathode electrode 1 and the grounded anode electrode 2 causes The material gas is ionized and a discharge phenomenon occurs. At this time, dissociation of the material gas is promoted by the generated plasma, and deposition of a film-forming material occurs on the substrate 1 mounted on the anode electrode 2.

Here, the frequency of the high-frequency voltage applied to the cathode electrode 1 is usually 13.56 MHz,
When the dimensions of the electrode are 800 mm square, a-S in the plasma CVD method using silane or the like as a material gas is used.
i: The film forming speed such as H, and the film quality formed are almost uniform in the electrode surface, have a large area of 1 m ² or more, and have high uniformity in which the variation rate of the film thickness is suppressed within ± 4%. Thus, a film formation process can be performed.

Here, the rate of change of the film thickness is defined by the following (1)
ΔT represented by the equation. T is a film thickness measured in each of a plurality of regions formed by dividing the substrate, and Ta is an average value of these film thicknesses.

ΔT = (T−Ta) / Ta × 100 (1) In addition, plasma is used for a film formation process on a large substrate used for a power a-Si: H thin film solar cell, a liquid crystal display device, or the like. When using CVD, the shape of the electrode is usually 1 m.
It is indispensable to use a device having a front and rear corner, and a technology capable of performing a highly uniform film forming process on a large area as described above.

On the other hand, in recent years, the frequency of the high-frequency power for generating the plasma has been increased from the RF band of 13.56 MHz to the VHF band of several tens of MHz, and further to the UHF band of several hundred MHz, thereby increasing the plasma density. There have been reported methods of increasing the film formation rate by increasing the film thickness and reducing the ion sheath voltage to reduce ion damage to the film. In particular, a relatively small area electrode is used,
As a method of performing plasma CVD by applying high frequency power in the HF band, a favorable film forming technique has already been reported (see Japanese Patent Application Laid-Open No. 6-77144).

[0009]

As described above, the plasma C
In the VD process, there is a great advantage to use an electromagnetic wave in the frequency range of the VHF band or the UHF band. However, when high-frequency power in the VHF band is applied to a film formation process in a large area, the film formation speed and The inconvenience of non-uniformity in the distribution of the film quality in the electrode surface was found.

That is, when a VHF band high-frequency power for plasma generation is used for a film forming apparatus having a large-area electrode, the film forming speed is significantly higher at the outer edge of the electrode than at the center of the electrode. Will decrease. Such non-uniformity of the film formation rate in the electrode surface and the non-uniformity of the film formation quality in the electrode surface due to the non-uniformity may lead to, for example, deterioration of the characteristics of the solar cell. This causes a serious problem in manufacturing a solar cell.

[0011] In order to investigate the cause of such non-uniformity in the film forming process, the inventors of the present invention have proposed a method of applying a high frequency voltage between an anode electrode and a cathode electrode. I examined the electric field distribution at.

First, the dimensions and shape of each electrode are 800 mm
When a high-frequency power having a frequency of 13.56 MHz is used, the dimension of one side of the electrode is about 1/28 of the high-frequency wavelength, and the phase of the electromagnetic wave propagating in the reaction vessel is equal to the entire region in the reaction vessel. Is almost constant.

At this time, as shown in FIG. 7, the high-frequency electric field intensity generated between the cathode and the anode obtained by the calculation of the electromagnetic field becomes almost constant in the plane, and uniform plasma generation in the electrode plane is realized. Is done. It was found that this contributed to the uniformity of the film forming speed and the film quality in the surface.

On the other hand, when considering a large-area film forming process using high-frequency power having a frequency in the VHF band, the wavelength of the high-frequency power becomes shorter as the frequency of the high-frequency power for plasma excitation increases, and the high-frequency power is propagated in the reaction vessel. A high-frequency phase difference. This causes non-uniformity of the electric field distribution between the cathode electrode and the anode electrode.

FIG. 8 shows that the dimensions and shape of the electrode are 800 mm square and the frequency of the high frequency used for plasma excitation is 81.3.
The distribution of the electric field between the electrodes obtained by the electromagnetic field calculation at 6 MHz is shown. In this case, the electrode dimensions are about 1 / 4.5 of the high frequency wavelength, and the in-plane distribution of the electric field between the electrodes is ± 6%. Further, when the dimensions of the electrodes are 1200 mm square, the electrode dimensions are about ３ of the wavelength of the high frequency, and the in-plane non-uniformity is ± 10%.
Also reach. FIG. 9 shows that the dimensional shape is 800 mm square to 120 mm.
The figure shows the results of examining how the in-plane non-uniformity of the electric field changes when the ratio of the electrode dimensions to the high-frequency wavelength is changed for an electrode having a square shape of 0 mm. Here, the in-plane non-uniformity of the electric field is expressed by the following equation (2).
This is the magnitude of the fluctuation range of E. E is the electric field strength in each of the plurality of regions formed by dividing the cathode electrode surface, and Ea is the average value of these electric field strengths.

ΔE = (E−Ea) / Ea × 100 (2) The non-uniformity of the electric field distribution between the electrodes, that is, the phenomenon that the electric field intensity decreases from the center of the electrode to the outer edge of the electrode is ,
The electrode size becomes remarkable from about 1/8 of the wavelength of the high frequency, and the non-uniformity increases as the electrode size with respect to the wavelength of the electromagnetic wave increases.

If the uniformity of the electric field distribution between the above-mentioned electrodes is lost, the uniformity of the plasma density distribution and the radical density distribution between the electrodes is deteriorated. It is difficult to ensure the uniformity of the quality of the formed film in the electrode surface.

Although the problem of the non-uniformity of the electric field distribution between the electrodes in the plasma CVD apparatus has been described above, the non-uniformity of the electric field distribution between the electrodes in the plasma etching apparatus also causes the problem. There is a problem in that the etching rate varies in the electrode plane, and it becomes difficult to ensure the uniformity of the etching rate in the electrode plane.

The present invention has been made to solve the above-described problems. Even when plasma excitation is performed using an electrode having a size that cannot be ignored with respect to the wavelength of an electromagnetic wave, a high-frequency electric field is not generated. It is an object of the present invention to obtain a plasma-excited chemical vapor deposition apparatus that can make the distribution in the electrode plane uniform, thereby making it possible to make the film formation rate and the quality of the formed film uniform in the electrode plane.

Further, according to the present invention, even when plasma excitation is performed using an electrode having a size that cannot be ignored with respect to the wavelength of an electromagnetic wave, the distribution of the high-frequency electric field in the electrode plane can be made uniform. It is an object of the present invention to obtain a plasma etching apparatus that can make an etching rate uniform within an electrode surface.

[0021]

According to a first aspect of the present invention, there is provided a plasma-excited chemical vapor deposition apparatus, comprising: a reaction vessel for performing a chemical vapor deposition process using plasma on a member to be processed; And a grounded anode electrode, and a cathode electrode disposed in the reaction vessel so as to face the anode electrode and to which a high-frequency voltage for exciting plasma is applied.

In this device, the anode electrode
Is a plate-shaped member to be processed, which faces the cathode electrode.
The mounting surface is flat, and the cathode electrode
At the outer edge of the surface of the pole facing the anode electrode,
From the outside to the outside at a predetermined interval
And as the height of each wall is outward
It is getting higher sequentially . Thereby, the above object is achieved.

[0023]

Preferably, the cathode electrode and the anode electrode each have a square shape, a rectangular shape, or another predetermined shape, and the length of one side of each of the square or rectangular electrodes, or The maximum dimension of each electrode having the other planar shape, which can be secured in the electrode plane, is reduced to 寸 法 or more and 以下 or less of the wavelength of the high frequency electric field excited from the cathode electrode.
Set .

Preferably, the frequency of the high-frequency electric field excited from the cathode electrode is 20 MHz or more and 200 MHz.
The value of the range Hz, constitutes used for the growth of the semiconductor thin film constituting the solar cell.

The plasma etching apparatus according to the present invention, a reaction vessel for performing a plasma etching process on the member to be processed, is placed in the reaction vessel, an anode electrode which is grounded, said in the reaction vessel A cathode electrode disposed to face the anode electrode and to which a high-frequency voltage for exciting plasma is applied.

[0027] In this plasma etching apparatus, the anode
The cathode electrode is a plate-shaped substrate facing the cathode electrode.
The surface for mounting the
The outer edge of the surface of the sword electrode facing the anode electrode
At the same time, a plurality of wall-shaped members
And the height of each wall member is outside.
It becomes higher gradually as it goes .

Hereinafter, the operation of the present invention will be described. In the present invention (claim 1), the distance between the cathode electrode and the anode electrode is set so that the intensity distribution of the electric field formed between the two electrodes is more uniform in a plane parallel to the processing surface of the member to be processed. As such, the electrode is made to be partially different in the plane, so that the size of the electrode is relatively large with respect to the wavelength of the high-frequency electric field due to an increase in the frequency of the high-frequency power applied to the cathode electrode. Even so, it is possible to suppress or avoid a decrease in the electric field strength at a portion far from the power supply point of the cathode electrode, which is caused by a gap between the parallel plate electrodes, and to prevent the anode electrode from being opposed to the cathode electrode in the plane (in the electrode plane). 2), a high uniformity of the film forming rate and the distribution of the film quality of the formed film can be secured.

As a result, the advantage of using high frequency electromagnetic waves in the VHF band or UHF band in the plasma CVD process, that is, an increase in the film formation rate due to an increase in the plasma density and an increase in ion damage to the film due to a decrease in the ion sheath voltage. It is possible to suppress or prevent the nonuniformity of the film forming speed and the film quality distribution in the electrode surface due to the increase in the frequency of the high frequency power for plasma excitation while making use of the reduction.

In the present invention (Claim 2), the cathode electrode has a shape in which the outer edge of the surface facing the anode electrode is raised, and the surface of the raised portion of the cathode electrode is formed in the anode electrode facing the anode electrode. The high-frequency electric field between the cathode electrode and the anode electrode, whose strength tends to decrease as the distance from the power supply point of the cathode electrode increases, becomes uniform in the electrode plane. It can be good.

In the present invention (claim 3), the cathode electrode and the anode electrode have a square shape, a rectangular shape, or another predetermined shape, respectively, and each of the electrodes having the square or rectangular planar shape is formed. The maximum dimension that can be secured in the electrode surface of each electrode having the length of one side or the other planar shape is １ ／ or more and 以下 or less of the wavelength of the high frequency electric field excited from the cathode electrode. , The plasma C using the cathode electrode and the anode electrode having various planar shapes is used.
In a VD apparatus, while making use of the advantage of using a high frequency in a VHF band or a UHF band for plasma CVD processing, the film forming speed and film quality in a large area film forming process caused by an increase in the frequency of a high frequency electric field of plasma excitation are made non-uniform. Can be suppressed or prevented.

In the present invention (claim 4), the frequency of the high-frequency electric field excited from the cathode electrode is set to 20M.
Hz and not higher than 200 MHz, which is used for growing a semiconductor thin film constituting a solar cell. Therefore, the film formation rate is increased by increasing the plasma density, and the film thickness is decreased by decreasing the ion sheath voltage. Ion impact damage can be suppressed. Thereby, a-Si: H
In the thin film constituting the solar cell, the ratio between the photoconductivity and the dark conductivity can be increased, and the defect density in the film can be reduced.

In the present invention (claim 5), the distance between the cathode electrode and the anode electrode is determined by adjusting the intensity distribution of the electric field formed between the two electrodes in a plane parallel to the processing surface of the member to be processed. The size of the electrode is relatively large with respect to the wavelength of the high-frequency electric field due to the increase in the frequency of the high-frequency power applied to the cathode electrode, because the frequency of the high-frequency electric power applied to the cathode electrode is increased. Even if the size of the cathode electrode is small, it is possible to suppress or avoid a decrease in the electric field strength at a portion far from the power supply point of the cathode electrode, which is caused by the gap between the parallel plate electrodes, and to prevent the anode electrode from facing the cathode electrode. High uniformity of the etching rate distribution (in the electrode plane) can be secured.

Thus, the advantage of using high-frequency electromagnetic waves in the frequency range of the VHF band or the UHF band for the plasma etching process, that is, the increase in the frequency of the high-frequency power for exciting the plasma while taking advantage of the increase in the etching rate due to the increase in the plasma density. Thereby, the nonuniformity of the etching rate distribution in the electrode surface can be suppressed or prevented.

[0035]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, an outline of the present invention will be described. In the high-frequency plasma CVD apparatus or etching apparatus of the present invention, as shown in FIG. 1, a cathode electrode 101 to which a high-frequency voltage is applied and a grounded anode electrode are placed in a reaction vessel 4 for performing a CVD process or an etching process. 2 are arranged so as to face each other. Here, each electrode has a square shape, and the dimension of one side thereof is not less than の and not more than の of the wavelength of the high-frequency voltage applied to the cathode electrode. The intensity of the electric field is made substantially uniform in the electrode plane, that is, in a plane parallel to the surface to be processed of the member to be processed.

In the above-mentioned reaction vessel, there is a portion where the distance between the two electrodes gradually narrows from the center to the outer edge of the electrode surface.

The change in the distance between the two electrodes is realized by changing the surface shape of the flat cathode electrode.

Further, the frequency of the high-frequency power applied to the cathode electrode is particularly set at 20 MHz or more and 200 MHz or less, thereby realizing a configuration usable for solar cell production.

Next, the basic principle of the present invention will be described in detail.
In the high-frequency plasma CVD apparatus according to the present invention, the material gas such as silane and hydrogen supplied into the apparatus is ionized by the high-frequency electric field to be in a plasma state (discharge state). This plasma dissociates the material gas, and as a result, the generated atomic radicals and molecular radicals are deposited on a substrate such as a silicon wafer substrate or glass attached to the anode electrode or the cathode electrode.

Therefore, by making the distribution of the high-frequency electric field substantially uniform in the electrode plane, the plasma is generated uniformly in the substrate plane, and the dissociation of the material gas is made uniform in the substrate plane. As a result, a highly uniform film formation process such as a film formation speed on a substrate and a film quality of a film formed on a substrate can be performed.

The high-frequency plasma CVD apparatus and the plasma etching apparatus according to the present invention are different from the ordinary parallel plate type apparatus in which the space between the anode electrode and the cathode electrode is uniformly spaced as shown in FIG. The distance between the two electrodes is gradually reduced from the center to the outer edge. This spatial change in the interelectrode gap is realized by deforming at least one of the cathode electrode 101 and the anode electrode 2 from a flat plate with a flat surface to a part with a raised surface.

Here, the spatial change of the gap between the electrodes is as follows.
Particularly, it is preferable that the shape of the cathode electrode is changed.
This is because a flat substrate is usually attached to the surface of the anode electrode, and thus it is appropriate to keep the anode electrode in a flat plate shape with a flat surface.

Further, as a method of deforming the shape of the electrode, a method of distorting the outer edge of the flat plate or a method of raising the outer edge of the flat plate can be adopted. The raised portion is formed of a single plate-shaped member, a structure in which a plurality of plate-shaped members are arranged in parallel at predetermined intervals, or a tapered member that becomes gradually thicker from the electrode center side to the electrode outer edge side. It can be structured.

The high-frequency electric field is formed over the entire surface of the electrode by supplying high-frequency power to the cathode electrode from the power supply point. Here, when the frequency of the high-frequency power is in the VHF band, the electric field intensity decreases in the peripheral portion in a device using a normal large-area parallel plate electrode. By locally narrowing the spacing, the high-frequency electric field between both electrodes can be locally increased. In other words, the tendency of the electric field strength to increase at the center of the electrode due to the nature of propagation of the high-frequency electromagnetic field such as the presence of a standing wave, in other words, the tendency of the electric field strength to decrease at the outer edge, and the narrower electrode spacing at the outer edge By doing so, the in-plane uniformity of the high-frequency electric field is substantially ensured.

That is, as shown in FIG. 9, the present invention is applied to a case of a normal plate electrode structure in which the dimension (electrode dimension) of one side of a square electrode is 1/8 or more with respect to the wavelength of an electromagnetic wave. It is effective in a region where the non-uniformity of the electric field distribution of the high-frequency electric field in the electrode surface becomes strong. In addition, under the condition that one standing wave exists in the electrode surface and the above-mentioned electrode dimension is 以下 or less of the high-frequency wavelength, that is, the high-frequency electric field is strong at the center of the electrode and the electric field is weak at the periphery of the electrode. This is effective for a region having such an electric field distribution (a range of a ratio between an electrode dimension and a wavelength of an electromagnetic wave).

Further, according to the present invention, it is possible to perform highly uniform discharge up to 15 m as an electrode dimension at a frequency of 10 MHz, up to 1.5 m at 100 MHz, up to 150 mm at 1 GHz, and to achieve high uniformity over a large area. Can be realized.

In particular, when the plasma CVD apparatus of the present invention is applied to the formation of a power a-Si: H thin film solar cell or the like, it is considered that an apparatus having an electrode size of about 1 m square is used. And the frequency is not less than 20 MHz (in this case, the electrode size / electromagnetic wave becomes 1/8 when the electrode size is 1880 mm square) and 200 MHz (in this case, when the electrode size is 750 mm square, the electrode size / electromagnetic wave This is effective when the following electromagnetic waves are used.

From the viewpoint of the actually formed thin film, when the frequency of the high frequency is 20 MHz or more,
While the generated plasma density increases, the deposition rate increases, whereas when a high frequency of about 200 MHz or higher is used, the frequency of collision between the plasma particles and the material gas decreases, and the plasma density decreases. Since the deposition rate is reduced, the effective frequency range is from 20 MHz to 200 MHz.

When the frequency is increased to 20 MHz or more, the ion sheath voltage is decreased, so that ion impact damage to the film is reduced and the quality of the formed film is improved. At this time, when examining the thin film of the a-Si: H solar cell, the ratio of photoconductivity to dark conductivity, which is an index of a high quality film, increases, and the defect density in the film decreases.

In the prior art, such plasma CVD
In the present invention, the effect of increasing the film forming speed by using the VHF band high frequency and improving the film quality of the formed film is not utilized in the case of forming a large area film.
The effect of the high frequency band can be utilized in a film forming process of high uniformity in a large area corresponding to a solar cell or the like.

Hereinafter, embodiments of the present invention will be described. (Embodiment 1) FIG. 1 is a view for explaining a high-frequency excitation plasma CVD apparatus according to Embodiment 1 of the present invention, and FIG. 1 (a) shows a schematic configuration of a reaction vessel of the apparatus. 1 (b) shows a planar shape of a cathode electrode provided in the reaction vessel.

In FIG. 1, reference numeral 100a denotes a reaction vessel 4 for performing chemical vapor deposition using high-frequency plasma, in which a semiconductor film or an insulating film is formed in the reaction vessel 4. This is a plasma CVD apparatus. The above reaction vessel 4
In the same manner as in the conventional plasma CVD apparatus 200, an anode electrode 2 on which a member to be processed 3 such as a semiconductor substrate is mounted is provided.
Are provided, and a cathode electrode 101 is provided so as to face the anode electrode 2. Here, the anode electrode 2 is grounded, and high frequency power is applied to the cathode electrode 101. A gas inlet 5 for introducing a material gas into the reaction vessel 4 is formed in a portion of the reaction vessel 4 facing the center of the cathode electrode. The high-frequency power applied to the cathode electrode 101 is also introduced. That is, in the reaction vessel 4, the inner conductor of the coaxial structure for injecting high-frequency power is brought into contact with the center of the cathode electrode, and the anode electrode 2 and the wall of the reaction vessel 4 are set to the ground potential.

In the first embodiment, the planar shape of the anode electrode 2 and the cathode electrode 101 is 8
It has a square shape of 00 mm, and the outer edge 1a of the cathode electrode 101 has a tapered swelling structure that becomes thicker toward the outside. That is, the distance between the anode electrode 2 and the cathode electrode 101 is 25 mm at the central portion 101b of the cathode electrode 101 as shown in FIG. It gradually narrows at a constant rate toward. Specifically, at the inner end of the outer edge 101a of the cathode electrode 101, the electrode interval is 25 mm,
At the outer end of 01a, the electrode interval is 22.5 mm. The dimension of the tapered raised structure in the direction parallel to the electrode surface is 200 mm.

Next, the function and effect will be described. FIG. 2 shows the cross-sectional structure of the anode electrode and the cathode electrode in the high-frequency plasma CVD apparatus of the first embodiment,
9 shows a calculation result of a high-frequency electric field distribution in a plane parallel to the anode electrode surface when a high-frequency voltage is applied to the cathode electrode of the plasma CVD apparatus having the above structure.

Here, the frequency of the high frequency for plasma excitation is 81.36 MHz, and the electrode size corresponds to about 1 / 4.5 of the high frequency wavelength. In FIG. 2, the decrease in the electric field strength at the outer edge of the electrode as shown in FIG. 8 is suppressed, and the in-plane distribution (nonuniformity) ΔE of the electric field strength is reduced to ± 2.5%. . That is, the intensity distribution of the electric field formed between the cathode electrode and the anode electrode is substantially uniform in a plane parallel to the processing surface of the member 3 to be processed.

It is apparent from calculation that the same electric field distribution can be realized by installing a plurality of plate-like protrusions (wall-like members) on the outer edge of the cathode electrode so as to be higher toward the outside and lower toward the inside. It has become.

Next, the film thickness distribution of the thin film formed in the reaction vessel 4 of the plasma CVD apparatus of the first embodiment is shown in FIG.
This will be described in comparison with the film thickness distribution of the thin film formed in the reaction vessel of the conventional apparatus shown in FIG.

First, the process of actually generating plasma and forming a thin film in the reaction vessel 4 shown in FIG. 1 is performed by changing the excitation frequency and the electrode size. Table 1 below shows the results obtained by measuring the film thickness distribution and the like of the formed thin film with respect to the ratio. As for the treatment using the reaction vessel 4 shown in FIG.
When the frequency is 12 MHz and the dimension and shape of the electrode are 800 mm
The figure shows a case where the frequency of the excitation high frequency is 81.36 MHz.

[0059]

[Table 1]

Table 1 shows that the reaction vessel 4 shown in FIG.
The figure also shows the results of actually generating plasma in the inside, forming a thin film, and measuring the film thickness distribution and the like of the formed thin film. In this case, the dimension and shape of the electrode are 800 mm square, and the frequency of the excitation high frequency is 13.56 MHz.

As setting parameters in each of the above film forming processes, the excitation high-frequency power applied to the cathode electrode is set to 0.1 W / cm ² , and the pressure of the atmosphere in the reaction vessel 4 is set to 0.1.
At 3 Torr, the source gases supplied into the reaction vessel are silane and hydrogen.

As can be seen from Table 1, when the ratio between the electrode size and the wavelength of the electromagnetic wave is 1/8 or more (27.12).
MHz and 81.36 MHz), as in the case where the ratio is 1/28 (13.56 MHz), the non-uniformity of the film thickness distribution remains at a small value. This is because the electric field distribution between them has been made uniform.

When the frequency becomes 20 MHz or more,
The film formation rate is increased, the ratio of the photoconductivity to the dark conductivity of the thin film is increased, and the defect density in the film is reduced. As a result, the film formation rate is improved and the film quality is improved.

That is, the use of the reaction vessel of Embodiment 1 shown in FIG.
Even when high-frequency power having a frequency in the VHF band of not less than z and not more than 200 MHz is applied, a film forming process of a large area and a high uniformity and a film forming process of a high-quality film at a high speed can be simultaneously achieved.

That is, the plasma CVD of the first embodiment
When considering the production of large thin-film solar cells for power,
This enables a higher-quality solar cell to be produced at a higher speed on a substrate having a large area equivalent to the conventional one.

As described above, in the present embodiment, the in-plane uniformity of the electric field between the electrodes when the electrode dimensions are 以上 to の 長 the length of the high-frequency wavelength is achieved, and the large area height is improved. This enables uniform film formation. Therefore, solar cells,
In the field of liquid crystal displays and large-scale integrated circuits, it is possible to increase the frequency of a high-frequency electromagnetic field for plasma excitation and to increase the area of a film-forming substrate, which greatly contributes to industrially improving the quality.

(Embodiment 2) FIG. 3 is a view for explaining a high-frequency plasma CVD apparatus according to Embodiment 2 of the present invention. FIG. 3 (a) shows a schematic configuration of a reaction vessel of the apparatus. FIG. 3B shows a planar shape of a cathode electrode provided in the reaction vessel.

In the figure, reference numeral 100 b denotes a reaction vessel 4 for performing chemical vapor deposition using high-frequency plasma, in which a semiconductor film or an insulating film is formed in the reaction vessel 4. This is a plasma CVD apparatus.

In the second embodiment, the planar shape of the anode electrode 2 and the cathode electrode 102 is 8
It has a square shape of 00 mm, and a wall-like member 102a is arranged on the surface of the cathode electrode 102 facing the anode electrode 2 along the outer edge thereof. Other configurations are the same as those of the plasma CVD apparatus 10 of the first embodiment.
Same as 0a.

In the second embodiment having such a configuration, the wall-shaped member is arranged along the outer edge on the surface of the cathode electrode 102 facing the anode electrode. There is an effect that the high-frequency electric field between the cathode electrode and the anode electrode, whose strength tends to decrease as the distance from the point increases, can be made uniform.

(Embodiment 3) FIG. 4 is a view for explaining a high-frequency plasma CVD apparatus according to Embodiment 3 of the present invention. FIG. 4 (a) shows a schematic configuration of a reaction vessel of the apparatus. FIG. 4B shows a planar shape of a cathode electrode provided in the reaction vessel.

In the figure, reference numeral 100c denotes a reaction vessel 4 for performing chemical vapor deposition using high-frequency plasma, in which a semiconductor film and an insulating film are formed in the reaction vessel 4. This is a plasma CVD apparatus.

In the third embodiment, the planar shape of the anode electrode 2 and the cathode electrode 102 is 8
It has a square shape of 00 mm, and the outer periphery of the surface of the cathode electrode 103 facing the anode electrode includes:
From the inner part to the outer part, a plurality of wall-like members 10
_{3a 1, 103a 2, 103a 3} , 103a 4, 103a 5
Are arranged at a predetermined interval, and the height of these wall-like members becomes higher toward the outside. Other configurations are the same as those of the plasma CVD apparatus 10 of the first embodiment.
Same as 0a.

In the third embodiment having such a configuration, a plurality of wall-shaped members are arranged at predetermined intervals from the inner portion to the outer portion on the outer peripheral portion of the surface of the cathode electrode facing the anode electrode. Since the height of the member is set to be higher toward the outer side, there is an effect that the high-frequency electric field between the cathode electrode and the anode electrode can be very effectively uniformed.

(Embodiment 4) FIG. 5 is a view for explaining a high-frequency plasma CVD apparatus according to Embodiment 4 of the present invention, and FIG. 5 (a) shows a schematic configuration of a reaction vessel of the apparatus. FIG. 5B shows a plan shape of a cathode electrode provided in the reaction vessel.

In the drawing, reference numeral 100 d denotes a reaction vessel 4 for performing chemical vapor deposition using high-frequency plasma, in which a semiconductor film or an insulating film is formed in the reaction vessel 4. This is a plasma CVD apparatus.

In the fourth embodiment, each of the cathode electrode 104a and the anode electrode 105 has a circular planar shape, and the length of the diameter of each of the electrodes is set to 1/1 / the wavelength of the high-frequency electric field excited from the cathode electrode. 8 or more and 1/2
The following dimensions are set, for example, 800 mm. The outer edge portion 104a of the cathode electrode 104 has a tapered swelling structure that becomes thicker toward the outside. In other words, the distance between the anode electrode 105 and the cathode electrode 104 is 25 mm at the central portion 104b of the cathode electrode 104, and the outer edge portion 104a is gradually increased at a constant rate from the inside to the outside by the tapered ridge structure. It is narrow. Specifically, at the inner end of the outer edge 104a of the cathode electrode 104, the electrode interval is 25 mm,
At the outer end of 04a, the electrode interval is 22.5 mm.

The other configuration is the same as that of the plasma CVD apparatus 100a of the first embodiment.

In the fourth embodiment having such a configuration, the cathode electrode and the anode electrode each have a circular planar shape, and the diameter of each electrode is equal to or more than １ ／ of the wavelength of the high-frequency electric field excited from the cathode electrode. In addition, since the size is set to be equal to or smaller than 1/2, in a plasma CVD apparatus using a circular cathode electrode and an anode electrode, the VHF band and the UH
While utilizing the advantage of using the high frequency of the F band for the plasma CVD process, it is possible to prevent the non-uniformity of the film forming speed and film quality in the large area film forming process caused by the increase in the frequency of the high frequency electric field of the plasma excitation. .

In the fourth embodiment, the outer edge 104a of the flat circular cathode electrode is formed to have a tapered swelling structure that becomes thicker toward the outside, but the structure of the cathode electrode is not limited to this. Instead, for example, a circular cathode electrode may be configured such that a wall-shaped member is arranged along the outer edge thereof on the surface facing the anode electrode, and the circular cathode electrode may be replaced with the anode electrode. A structure in which a plurality of wall-shaped members are arranged at predetermined intervals from the inner part to the outer part on the outer peripheral portion of the surface facing the above.

Further, in each of the above embodiments, the case where the planar shape of the cathode electrode and the anode electrode is square or circular has been described. However, the planar shape of both electrodes is not limited to these, and may be, for example, a rectangular shape. , A pentagonal shape, a hexagonal shape, or another predetermined planar shape.

In this case, the length of one side of the cathode and anode electrodes having a rectangular planar shape, or the maximum dimension of the cathode electrode and the anode electrode having another planar shape, which can be secured in the electrode plane, is determined by the cathode electrode. Plasma CVD using a cathode electrode and an anode electrode having the above-mentioned planar shape by setting the dimension to １ ／ or more and 以下 or less of the wavelength of the high frequency electric field excited from
As the apparatus, an apparatus having a high film-forming speed and little damage to the film and capable of preventing the film-forming speed and the film quality from being uneven in a large-area film-forming process can be obtained.

Further, in each of the above embodiments, a plasma CVD apparatus having a reaction vessel for performing a chemical vapor deposition process using plasma has been described as an example, but the structure of the cathode electrode and the anode electrode shown in each of the above embodiments has been described. It is needless to say that the method is also effective for an in-plane highly uniform etching process using a plasma dry etching (asher) apparatus for etching a film with plasma particles and active species generated by plasma excitation. That is, by disposing the cathode electrode and the anode electrode having the structure shown in each of the above embodiments in a reaction vessel for performing a plasma etching process, a plasma etching apparatus capable of performing a uniform and high-speed etching process in a large area. Can be realized. In this case, an etching gas such as CF ₄ or NF ₃ is used instead of the material gas for film formation, and this etching gas is dissociated and excited by plasma.

Further, in the above description, the electric field intensity distribution formed between the cathode electrode and the anode electrode is made substantially uniform within a plane parallel to the processing surface of the member to be processed. Although the case where the distance between them is partially different in the plane has been described, the setting of the distance at each part between the cathode electrode and the anode electrode depends on the intensity distribution of the electric field formed between the two electrodes. The material to be processed may not be substantially uniform in a plane parallel to the processing surface of the member to be processed, but may be any material as long as it becomes more uniform. In this case, since the uniformity of the intensity distribution of the electric field between the cathode electrode and the anode electrode is enhanced, the advantage of using the high-frequency electromagnetic waves in the VHF band or UHF band in the plasma CVD process, that is, the plasma density is reduced. The film deposition rate and film quality distribution in the electrode surface are not improved by increasing the frequency of the high-frequency power for plasma excitation, while taking advantage of the increase in the film deposition rate due to the increase and the reduction of ion damage to the film due to the decrease in the ion sheath voltage. Uniformity can be suppressed or prevented.

[0085]

As described above, according to the plasma-excited CVD apparatus according to the present invention (claim 1), the distance between the cathode electrode and the anode electrode is determined by the intensity distribution of the electric field formed between the two electrodes. Are made to be partially different in the plane parallel to the processing surface of the member to be processed, so that high-frequency electromagnetic waves in the VHF band or UHF band are used for the plasma CVD process. While taking advantage of the advantages of the use, namely, the increase in the deposition rate due to the increase in plasma density and the reduction in ion damage to the film due to the decrease in the ion sheath voltage, the frequency of the high-frequency power for plasma excitation is increased in the electrode plane. This has the effect of suppressing or preventing non-uniformity of the film forming rate and film quality distribution.

According to this invention (Claim 2), the cathode electrode has a shape in which the outer edge of the surface facing the anode electrode is raised, and the surface of the raised portion of the cathode electrode is formed in the anode electrode facing the anode electrode. The high-frequency electric field between the cathode electrode and the anode electrode, whose strength tends to decrease as the distance from the power supply point of the cathode electrode increases, increases the distance between the cathode electrode and the anode electrode. Good uniformity can be obtained.

According to the present invention (claim 3), the cathode electrode and the anode electrode have a square shape, a rectangular shape, or another predetermined shape, respectively, and each of the cathode electrode and the anode electrode has the square or rectangular planar shape. The length of one side of the electrode, or the maximum dimension of each electrode having the other planar shape, which can be secured in the electrode plane, is set to １ ／ or more and ２ of the wavelength of the high-frequency electric field excited from the cathode electrode. Since the following dimensions were set, the plasma C using the cathode electrode and the anode electrode having a predetermined planar shape was used.
As the VD apparatus, an apparatus having a high film forming speed and little damage to the film and capable of suppressing or preventing nonuniform film forming speed and film quality in a large area film forming process can be obtained.

According to the present invention (claim 4), the frequency of the high-frequency electric field excited from the cathode electrode is set to 20 MHz.
Since the value is in the range of not less than z and not more than 200 MHz, a
A plasma CVD apparatus suitable for forming a thin film constituting a -Si: H solar cell can be obtained.

According to the plasma etching apparatus of the present invention (claim 5), the distance between the cathode electrode and the anode electrode depends on the intensity distribution of the electric field formed between the two electrodes. VH is made to be partially different in a plane parallel to the plane so as to be more uniform in the plane.
The advantage of using high-frequency electromagnetic waves in the frequency band of the F band or UHF band for the plasma etching process, that is, the increase in the etching rate due to the increase in the plasma density, and the increase in the frequency of the high-frequency power for plasma excitation within the electrode surface. This has the effect of preventing or preventing the etching rate distribution from becoming non-uniform.

[Brief description of the drawings]

FIG. 1 is a high-frequency plasma CV according to a first embodiment of the present invention.
FIG. 1A is a view for explaining a D apparatus. FIG. 1A shows a schematic configuration of a reaction vessel of the apparatus, and FIG. 1B shows a plan shape of a cathode electrode provided in the reaction vessel. ing.

FIG. 2 shows a cross-sectional structure of an anode electrode and a cathode electrode in the high-frequency plasma CVD apparatus according to the first embodiment, and an anode electrode surface between the two electrodes when a high-frequency voltage having a frequency of 81.36 MHz is applied to the cathode electrode. FIG. 4 is a diagram showing an intensity distribution of a high-frequency electric field in the inside.

FIG. 3 is a high-frequency plasma CV according to a second embodiment of the present invention.
FIG. 3A is a view for explaining a D apparatus, FIG. 3A shows a schematic configuration of a reaction vessel of the apparatus, and FIG. 3B shows a plane shape of a cathode electrode provided in the reaction vessel. ing.

FIG. 4 is a high-frequency plasma CV according to Embodiment 3 of the present invention.
FIG. 4A is a view for explaining a D apparatus, FIG. 4A shows a schematic configuration of a reaction vessel of the apparatus, and FIG. 4B shows a planar shape of a cathode electrode provided in the reaction vessel. ing.

FIG. 5 is a high-frequency plasma CV according to a fourth embodiment of the present invention.
FIG. 5A is a view for explaining a D apparatus, FIG. 5A shows a schematic configuration of a reaction vessel of the apparatus, and FIG. 5B shows a planar shape of a cathode electrode provided in the reaction vessel. ing.

FIG. 6 is a schematic view for explaining a conventional high-frequency plasma CVD apparatus. FIG. 6 (a) shows a schematic configuration of a reaction vessel of the apparatus, and FIG. 6 (b) is provided inside the reaction vessel. 2 shows a planar shape of a cathode electrode.

FIG. 7 shows a cross-sectional structure of an anode electrode and a cathode electrode in a conventional high-frequency plasma CVD apparatus, and a high-frequency electric field in an electrode plane between the two electrodes when a high-frequency voltage having a frequency of 13.56 MHz is applied to the cathode electrode. It is a figure showing an intensity distribution.

FIG. 8 shows a cross-sectional structure of an anode electrode and a cathode electrode in a conventional high-frequency plasma CVD apparatus, and a high-frequency electric field in an electrode plane between the two electrodes when a high-frequency voltage having a frequency of 81.36 MHz is applied to the cathode electrode. It is a figure showing an intensity distribution.

FIG. 9 shows a conventional high-frequency plasma CVD apparatus.
FIG. 6 is a diagram showing the dependence of the ratio between the wavelength of the electromagnetic wave and the electrode dimensions on the non-uniformity of the intensity distribution of the high-frequency electric field between the electrodes.

[Explanation of symbols]

2 Anode electrode 3 Substrate 4 Reaction vessel 5 Gas inlet 100a, 100b, 100c, 100d Plasma C
VD device 101, 102, 103 cathode electrodes 101a rectangular tapered structure (outer edge portion) 102a, 103a ₁ ~103a ₅ wall-like member 104 circular cathode electrode 104a circular tapered structure (outer edge)

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Koji Tomita 22-22 Nagaikecho, Abeno-ku, Osaka-shi, Osaka Inside Sharp Corporation (72) Inventor Yoshihiro Yamamoto 22-22 Nagaikecho, Abeno-ku, Osaka-shi, Osaka Sharp Corporation (56) References JP-A-7-122502 (JP, A) JP-A-6-295866 (JP, A) JP-A-6-77144 (JP, A) JP-A-3-99767 (JP, U) Japanese Utility Model Application No. Sho 64-13119 (JP, U) Japanese Utility Model Application No. Hei 4-103641 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01L 21/205 C23C 16/50 H01L 21/3065 H05H 1/46

Claims (4)

(57) [Claims] 1. A reaction container for performing chemical vapor deposition using plasma on a member to be processed, an anode electrode disposed in the reaction container and grounded, and an anode electrode disposed in the reaction container. A cathode electrode to which a high-frequency voltage for exciting plasma is applied, wherein the anode electrode faces the cathode electrode, and a surface for mounting a plate-shaped member to be processed is flat. Outside the surface of the cathode electrode facing the anode electrode.
A plurality of wall-shaped members from the inside to the outside
It is arranged at intervals and the height of each wall-shaped member is outside
A plasma-excited chemical vapor deposition apparatus characterized in that the height is gradually increased as the temperature becomes higher . 2. The plasma-excited chemical vapor deposition apparatus according to claim 1 , wherein each of the cathode electrode and the anode electrode has a square shape, a rectangular shape, or another predetermined planar shape. The length of one side of each electrode having a planar shape, or the maximum dimension of each other electrode having a planar shape, which can be ensured in the electrode plane, is 1/1 / wavelength of the high-frequency electric field excited from the cathode electrode. 8 or more and 1
A plasma-excited chemical vapor deposition apparatus set to a size of / 2 or less. 3. The plasma-excited chemical vapor deposition apparatus according to claim 1 , wherein a frequency of the high-frequency electric field excited from the cathode electrode is a value in a range from 20 MHz to 200 MHz, and Plasma-enhanced chemical vapor deposition equipment used to grow semiconductor thin films. 4. A reaction container for performing a plasma etching process on a member to be processed, an anode electrode arranged in the reaction container and grounded, and an anode electrode arranged in the reaction container so as to face the anode electrode. And a cathode electrode to which a high-frequency voltage for exciting plasma is applied. The anode electrode has a flat surface for mounting a plate-shaped member to be treated, which is opposed to the cathode electrode. Outside the surface of the cathode electrode facing the anode electrode.
A plurality of wall-shaped members from the inside to the outside
It is arranged at intervals and the height of each wall-shaped member is outside
A plasma etching apparatus characterized in that the height gradually increases as the temperature increases .