WO2013057835A1 - Thin film forming apparatus - Google Patents

Abstract

This thin film forming apparatus forms a thin film on a substrate. The thin film forming apparatus is provided with: a chamber having a substrate stored therein; a substrate plate, which is disposed in the chamber, and has the substrate placed thereon; a high frequency electrode, which is disposed in the chamber, and faces the substrate on the substrate plate; a gas supply mechanism, which supplies to the inside of the chamber, a pretreatment gas containing hydrogen, or a reaction gas containing a raw material gas of the thin film to be formed on the substrate; and an alternating current power supply, which supplies alternating current power to between the substrate plate and the high frequency electrode, and on an upper surface of the substrate in different steps in film forming process, excites plasma containing the pretreatment gas, or plasma containing the raw material gas.

Description

Thin film forming equipment

The present invention relates to a thin film forming apparatus for forming a thin film on a substrate.

In the semiconductor device manufacturing process, a plasma processing apparatus is used in a film forming process, an etching process, an ashing process, and the like because of high-precision process control. For example, a plasma chemical vapor deposition (CVD) apparatus is known as an apparatus used in a thin film forming process. In the plasma CVD apparatus, the source gas is turned into plasma by high-frequency power or the like, and a thin film is formed on the substrate by a chemical reaction.

In order to remove the residual gas in the chamber of the plasma CVD apparatus, a method of performing a plasma treatment as a pretreatment of the film formation process (hereinafter referred to as “film formation pretreatment”) has been proposed (for example, a patent). Reference 1).

JP-A-6-45255

Generally, a silicon nitride film is used as an antireflection film and a passivation film of a crystalline silicon solar cell. The conversion efficiency indicating the performance of the solar cell varies depending on the film quality of the silicon nitride film.

Demand for high conversion efficiency and low cost for solar cells is high, and it is necessary to further increase the conversion efficiency. If the structure of the solar cell is changed and a complicated process is added in addition to the process of using the thin film forming apparatus, the efficiency can be improved, but the cost is increased. For this reason, it is desired to improve the conversion efficiency of the solar cell by measures in the film forming process using the thin film forming apparatus.

Until now, sufficient studies have not been made to increase the efficiency of the film formation pretreatment in the formation of the antireflection film and passivation film of the solar cell. An object of this invention is to provide the thin film formation apparatus which performs the film-forming pretreatment which improves the conversion efficiency of a solar cell.

According to one aspect of the present invention, there is provided a thin film forming apparatus for forming a thin film on a substrate, comprising: (a) a chamber in which the substrate is stored; (b) a substrate plate that is disposed in the chamber and places the substrate; (C) a high-frequency electrode disposed in the chamber and facing the substrate on the substrate plate; and (d) either a pretreatment gas containing hydrogen or a reactive gas containing a raw material gas for a thin film formed on the substrate. (E) supplying AC power between the substrate plate and the high-frequency electrode, and forming either the plasma containing the pretreatment gas or the plasma containing the source gas on the upper surface of the substrate in the film forming step There is provided a thin film forming apparatus including an AC power source that is excited at different stages.

According to the present invention, it is possible to provide a thin film forming apparatus that performs film formation pretreatment for improving the conversion efficiency of a solar cell.

It is a schematic diagram which shows the structure of the thin film forming apparatus which concerns on the 1st Embodiment of this invention. It is a flowchart for demonstrating the thin film formation method using the thin film forming apparatus which concerns on the 1st Embodiment of this invention. It is a schematic diagram for demonstrating the film-forming pretreatment using the thin film forming apparatus which concerns on the 1st Embodiment of this invention. It is a graph which shows the relationship between the frequency of the electric power supplied, and the number of ions which collide with the substrate surface. It is a table | surface which shows the comparison with the thin film formed by the thin film forming apparatus which concerns on the 1st Embodiment of this invention, and the thin film formed by a comparative example. It is a schematic diagram which shows the structure of the sample for measuring conversion efficiency. It is a schematic diagram which shows the structure of the sample for measuring carrier lifetime. It is a schematic diagram which shows the structure of the thin film forming apparatus which concerns on the 2nd Embodiment of this invention. It is a table | surface which shows the comparison with the thin film formed by the thin film forming apparatus which concerns on the 2nd Embodiment of this invention, and the thin film formed by a comparative example. It is a schematic diagram which shows the structure of the thin film forming apparatus which concerns on the 3rd Embodiment of this invention. It is a schematic diagram which shows the example of the groove | channel formed in the surface of the high frequency power supply of the thin film forming apparatus which concerns on the 3rd Embodiment of this invention. It is a schematic diagram which shows the structure of the thin film forming apparatus which concerns on the modification of the 3rd Embodiment of this invention.

The first to third embodiments of the present invention will be described with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, it should be noted that the drawings are schematic. Further, the following first to third embodiments exemplify apparatuses and methods for embodying the technical idea of the present invention, and the embodiments of the present invention include the structure of component parts, The arrangement is not specified as follows. The embodiment of the present invention can be variously modified within the scope of the claims.

(First embodiment)
A thin film forming apparatus 10 according to the first embodiment of the present invention is a thin film forming apparatus that forms a thin film 110 on a substrate 100 as shown in FIG. A thin film forming apparatus 10 illustrated in FIG. 1 includes a chamber 11 in which a substrate 100 is stored, a substrate plate 12 that is disposed in the chamber 11 and on which the substrate 100 is placed, and a substrate on the substrate plate 12 that is disposed in the chamber 11. A gas supply mechanism 15 for supplying one of a high-frequency electrode 13 facing 100, a pretreatment gas 121 containing hydrogen, or a reaction gas 122 containing a raw material gas for a thin film 110 formed on the substrate 100 into the chamber 11; An AC power source that supplies AC power between the substrate plate 12 and the high-frequency electrode 13 and excites either the plasma containing the pretreatment gas 121 or the plasma containing the source gas on the upper surface of the substrate 100 at different stages of the film forming process. 14.

The gas supply source 18 shown in FIG. 1 includes a pretreatment gas source 181 that stores the pretreatment gas 121 and a reaction gas source 182 that stores the reaction gas 122. However, when the reaction gas source 182 includes a plurality of source gases, if any of those source gases can be used as the pretreatment gas, the gas supply source 18 does not include the pretreatment gas source 181 and the reaction is performed. A structure having only the gas source 182 may be used. The pretreatment gas 121 and the reaction gas 122 supplied from the gas supply source 18 are supplied into the chamber 11 through the gas supply mechanism 15. The gas supply mechanism 15 is provided with a flow rate controller, and supplies a certain amount of pretreatment gas 121 or reaction gas 122 into the chamber 11.

The thin film forming apparatus 10 further includes a gas exhaust mechanism 16 that exhausts the gas in the chamber 11 to the outside. The gas exhaust mechanism 16 is provided with a gas pressure regulating valve to keep the pressure in the chamber 11 constant.

Referring to FIG. 2, an example of a method for forming a thin film by the thin film forming apparatus 10 shown in FIG. 1 will be described below.

In step S <b> 11, the substrate 100, which is a semiconductor silicon substrate targeted for film formation, is stored in the chamber 11.

In step S <b> 12, the pretreatment gas 121 is introduced into the chamber 11 by the gas supply mechanism 15. The pretreatment gas 121 is preferably ammonia (NH ₃ ) gas, a mixed gas of ammonia and nitrogen (N ₂ ), or the like.

In step S13, the inside of the chamber 11 is depressurized by the gas exhaust mechanism 16, and the pressure of the pretreatment gas 121 in the chamber 11 is set to a predetermined value.

In step S 14, the AC power supply 14 is turned on, and predetermined AC power is supplied between the substrate plate 12 and the high-frequency electrode 13 through the matching box 141. Thereby, the pretreatment gas 121 in the chamber 11 is turned into plasma, and the film formation pretreatment is started. That is, the surface of the substrate 100 before film formation is exposed to high frequency plasma of ammonia (hereinafter referred to as “ammonia plasma”), and the hydrogen radicals in the ammonia plasma are not bonded to the substrate 100 as shown in FIG. Bond with (dangling bond).

After performing the pre-deposition process for a predetermined period, the AC power supply 14 is turned off in step S15, and the pre-deposition process is terminated. Thereafter, in step S16, the pretreatment gas 121 is exhausted by the gas exhaust mechanism 16, and the chamber 11 is evacuated.

Next, in step S 17, the reaction gas 122 is introduced into the chamber 11 by the gas supply mechanism 15. In step S18, the inside of the chamber 11 is depressurized by the gas exhaust mechanism 16, and the reaction gas 122 in the chamber 11 is adjusted to a predetermined gas pressure.

Thereafter, in step S 19, the AC power supply 14 is turned on, and predetermined AC power is supplied between the substrate plate 12 and the high-frequency electrode 13 by the AC power supply 14 via the matching box 141. Thereby, the reaction gas 122 containing the source gas in the chamber 11 is turned into plasma. By exposing the substrate 100 to the formed plasma, excited species in the plasma are reacted on the surface of the substrate 100, and the thin film 110 is formed on the surface of the substrate 100.

After growing the thin film 110 to a predetermined thickness, the AC power supply 14 is turned off in step S20, and the film forming process is terminated. Thereafter, in step S21, the reaction gas 122 is exhausted by the gas exhaust mechanism 16, and the chamber 11 is evacuated. Thus, the thin film 110 is formed on the substrate 100.

In the above description, the example in which the pretreatment gas 121 is exhausted from the chamber 11 in step S16 has been described. However, when the source gas contained in the reaction gas 122 includes the pretreatment gas 121, step S16 of exhausting the pretreatment gas 121 from the chamber 11 may be omitted.

For example, when ammonia gas is used for the pretreatment gas 121, the above step S16 can be omitted if the source gas contains ammonia gas. Further, the gas supply source 18 can be constituted by only the reactive gas source 182.

Generally, a crystalline silicon substrate is used as a substrate for a crystalline silicon solar cell. In a polycrystalline silicon substrate, a grain boundary of polycrystalline silicon becomes a defect. Carriers are supplemented by this defect, and the conversion efficiency (hereinafter simply referred to as “conversion efficiency”) of the solar cell is lowered.

However, according to the thin film formation method described above, the hydrogen radicals in the ammonia plasma are combined with the dangling bonds of the substrate 100 by the film formation pretreatment. This reduces carrier supplementation due to defects and increases the passivation effect. As a result, the carrier lifetime in the substrate 100 is increased. Therefore, conversion efficiency is improved by applying the above method to the formation of an antireflection film or a passivation film of a solar cell.

Figure 4 shows the relationship between the frequency of power supplied between the electrodes and the number of ions colliding with the substrate surface (Akihisa Matsuda et al., “Influence of Power-Source Frequency on the Properties of GD a-Si: H”, Japanese Journal of Applied Physics, Vol.23, N0.8, August, 1984, L568-L569). As shown in FIG. 4, when the frequency is 10 kHz to 500 kHz, the number of ions that collide with the substrate is large, and when the frequency is 1 MHz or more, the number of ions that collide with the substrate is small.

That is, when the frequency of the AC power supplied between the substrate plate 12 and the high-frequency electrode 13 by the AC power source 14 is lower than 1 MHz, the number of hydrogen ions that collide with the substrate 100 is large, and the passivation effect is large. Therefore, it is preferable to set the frequency of the AC power to be low. For this reason, the frequency of the AC power supplied from the AC power supply 14 is preferably about 40 KHz to 450 KHz, for example. For example, AC power having a frequency of 250 KHz is supplied between the substrate plate 12 and the high-frequency electrode 13.

In the production of a crystalline silicon solar cell, the substrate 100 is a substrate in which an n-type semiconductor layer having a surface diffusion concentration of 1 × 10 ¹⁸ to 1 × 10 ²² is formed on a p-type silicon substrate, or an n-type silicon substrate. Further, a substrate on which a p-type semiconductor layer having a surface diffusion concentration of 1 × 10 ¹⁸ to 1 × 10 ²² is formed can be used. When the antireflection film of the solar cell is used, the thin film 110 is a silicon nitride (SiN) film having a refractive index of 1.8 to 3.0 and a film thickness of about 50 to 150 nm.

In order to form the thin film 110 made of a silicon nitride film on the substrate 100, monosilane, ammonia, or the like is used as a source gas, and nitrogen (N), hydrogen (H), argon (Ar), helium (as a carrier gas) He) and the like are used.

Note that it is preferable to set the substrate 100 to 250 ° C. to 550 ° C. in the state where the plasma of the source gas is excited in the chamber 11 in terms of realizing high conversion efficiency. At the substrate temperature, a high conversion efficiency of 15.6% to 16% or more is obtained.

In the thin film forming apparatus 10 shown in FIG. 1, the temperature of the substrate 100 can be arbitrarily set by the heater 17 built in the substrate plate 12. As described above, high conversion efficiency can be obtained by setting the temperature of the substrate 100 to 250 ° C. to 550 ° C. Further, it is more preferable that the temperature of the substrate 100 is 400 ° C. to 450 ° C.

FIG. 5 shows the conversion efficiency of the solar cell and the carrier lifetime of the substrate 100 after film formation when the film formation pretreatment is performed using the thin film forming apparatus 10 and when the film formation pretreatment is not performed. The comparison result of is shown. In FIG. 5, in the manufacturing method A of the comparative example, when the pre-deposition process is not performed, that is, steps S12 to S16 of the flowchart shown in FIG. 2 are not performed, the thin film 110 is formed by steps S17 to S20. It is a method to do. On the other hand, the manufacturing method B for performing the pre-deposition treatment is a manufacturing method according to the flowchart shown in FIG.

In order to measure the conversion efficiency shown in FIG. 5, a sample in which a silicon nitride film was formed as an antireflection film of a crystalline silicon solar cell was prepared. That is, a thin film 110 that is a silicon nitride film is formed over the substrate 100 that is a polycrystalline silicon substrate. FIG. 6 shows a specific configuration example of the created sample. by diffusing phosphorus (P) on the surface of the p-type polycrystalline silicon substrate 51 to form an n ⁺ diffusion region, n ⁺ diffusion regions on a silicon nitride (SiN) film 52 is disposed. A silver (Ag) electrode 53 is disposed on the silicon nitride film 52, and an aluminum (Al) electrode 54 is disposed on the back surface of the polycrystalline silicon substrate 51. The refractive index of the silicon nitride film 52 is about 2.0 to 2.15, and the film thickness is about 75 to 90 nm. The conversion efficiency was obtained by irradiating the sample shown in FIG. 6 with light and measuring current and voltage.

Further, as a sample for measuring the carrier lifetime of the substrate 100 after film formation, silicon nitride films 62 and 63 are formed on both surfaces of an n-type single crystal silicon substrate 61 as shown in FIG. The sample which formed was prepared. The carrier lifetime was measured by the μ-PCD method for measuring the amount of carriers generated in the sample irradiated with the laser.

As shown in FIG. 5, in the manufacturing method A in which the film formation pretreatment is not performed, the conversion efficiency is 15.09%, and the carrier lifetime of the substrate is 2475 μsec. On the other hand, in the manufacturing method B in which the film formation pretreatment is performed, the conversion efficiency is 15.14% and the carrier lifetime of the substrate is 2808 μsec. That is, it was confirmed that the conversion efficiency and the carrier lifetime of the substrate are improved by performing the pre-deposition treatment shown in FIG.

Note that the film formation pretreatment conditions of the manufacturing method B are as follows: the pretreatment gas 121 is ammonia gas, the pressure of the pretreatment gas 121 in the chamber 11 is 100 Pa, the treatment time for exposing the substrate 100 to ammonia plasma is 15 seconds, and alternating current is used. The power density of the power source 14 was 83 mW / cm ² .

As described above, in the thin film forming apparatus 10 according to the first embodiment of the present invention, the passivation effect of the substrate 100 is enhanced by exposing the substrate 100 to plasma containing hydrogen before performing the film forming process. As a result, according to the film forming method using the thin film forming apparatus 10, the carrier lifetime in the substrate 100 becomes long, and the conversion efficiency of the solar cell can be improved.

(Second Embodiment)
In the thin film forming apparatus 10 according to the second embodiment of the present invention, the substrate 100 is arranged vertically as shown in FIG. In the thin film forming apparatus 10 shown in FIG. 8, the substrate plate 12 and the high-frequency electrode 13 have a comb shape having a plurality of tooth portions respectively extending in the vertical direction toward the paper surface. The comb teeth are arranged in the shape of cross fingers. Since the substrate 100 is mounted on each of a plurality of tooth portions facing the high-frequency electrode 13 of the substrate plate 12, a large number of substrates 100 can be processed at a time.

A groove 132 is formed so as to have an opening on the surface of the tooth portion of the high-frequency electrode 13, and the high-frequency electrode 13 functions as a hollow cathode electrode. In the example shown in FIG. 8, the groove 132 is formed through the tooth portion of the high-frequency electrode 13. Electron confinement occurs in the groove 132 due to the hollow cathode effect, and high-density plasma is stably generated in a form supplied from the groove 132. As a result, the pretreatment gas 121 and the source gas are efficiently decomposed, and the film formation pretreatment and film formation processing for the plurality of substrates 100 can be performed in a short time.

In FIG. 9, regarding the conversion efficiency of the solar cell and the carrier lifetime of the substrate 100 after film formation, when the film formation pretreatment is performed using the thin film forming apparatus 10 illustrated in FIG. 8, the film formation pretreatment is not performed. The comparison result in the case of the comparative example is shown. In FIG. 9, the manufacturing method A of the comparative example does not perform the film formation pretreatment, that is, does not perform steps S12 to S16 of the flowchart shown in FIG. 2, but forms the thin film 110 by steps S17 to S20. Is the method. On the other hand, the manufacturing method B for performing the pre-deposition treatment is a manufacturing method according to the flowchart shown in FIG.

As in the case of the comparison shown in FIG. 5, a silicon nitride film was formed as an antireflection film of a crystalline silicon solar cell, and a sample for measuring conversion efficiency was created (see FIG. 6). As a sample for measuring the carrier lifetime of the substrate 100 after film formation, a sample was prepared in which a silicon nitride film was formed on both surfaces of a single crystal silicon substrate in the same manner as the antireflection film of the solar cell (see FIG. 7). ).

The conditions for the film formation pretreatment are as follows: the pretreatment gas 121 is ammonia gas, the pressure of the pretreatment gas 121 in the chamber 11 is 67 Pa, the treatment time for exposing the substrate 100 to ammonia plasma is 5 seconds, and the power density of the AC power supply 14 is It was set to 400 mW / cm ² . By adopting a hollow cathode electrode as the high-frequency electrode 13, the pressure of the pretreatment gas 121 is reduced and the power density is increased as compared with the case where the thin film forming apparatus 10 shown in FIG. 1 is used.

As shown in FIG. 9, in the manufacturing method A in which the film formation pretreatment is not performed, the conversion efficiency is 16.26%, and the carrier lifetime of the substrate is 526 μsec. On the other hand, in the manufacturing method B in which the film formation pretreatment is performed, the conversion efficiency is 16.44% and the carrier lifetime of the substrate is 6751 μsec. In other words, the conversion efficiency and the carrier lifetime of the substrate are improved by performing the film formation pretreatment shown in FIG.

From the comparison between FIG. 5 and FIG. 9, the thin film forming apparatus using the hollow cathode discharge has a greater effect of the film formation pretreatment using the pretreatment gas 121 than the thin film forming apparatus not using the hollow cathode discharge. It can be said. Others are substantially the same as those in the first embodiment, and redundant description is omitted.

(Third embodiment)
In the thin film forming apparatus 10 according to the third embodiment of the present invention, as shown in FIG. 10, grooves 132 are formed on the surface of the high-frequency electrode 13 facing the substrate 100 on the substrate plate 12. In addition, openings of a plurality of ejection holes 131 are formed at the bottom of the groove 132 formed in the high-frequency electrode 13. Other configurations are the same as those of the first embodiment shown in FIG.

The high frequency electrode 13 of the thin film forming apparatus 10 shown in FIG. 10 functions as a hollow cathode electrode that generates a hollow cathode discharge. That is, electrons are confined by the hollow cathode effect in the groove 132 formed on the surface of the high-frequency electrode 13, and high-density plasma is stably generated in a form supplied from the groove 132.

Also, the pretreatment gas 121 or the reaction gas 122 is introduced into the chamber 11 from the inside of the high frequency electrode 13 through the ejection hole 131. That is, the high-frequency electrode 13 is integrated with a shower head type inlet for introducing the reaction gas 122 and the like into the surface of the substrate 100. For example, long cylindrical recesses are arranged in a lattice pattern on the surface of the high-frequency electrode 13, and these recesses are connected by grooves. A small-diameter ejection hole 131 is formed at the bottom of the long cylindrical recess.

FIG. 11 shows an example in which grooves 132 are continuously formed around the openings of the ejection holes 131 along the arrangement direction of the ejection holes 131 for one row on the surface 130 of the high-frequency electrode 13. If it is arranged around the opening of the ejection hole 131, various configurations can be adopted for the layout of the groove 132. For example, the grooves 132 may be formed in a lattice shape so that the openings of the ejection holes 131 are arranged at the intersections of the lattice.

The plasma can be stably formed by increasing the width of the groove 132. However, since the plasma state tends to become unstable if the width is too wide, the groove 132 preferably does not exceed 10 mm. For this reason, the width of the groove 132 is set to 2 mm to 10 mm, for example. In addition, although the diameter of the opening part of the ejection hole 131 is dependent also on the number of the ejection holes 131 formed in the high frequency electrode 13, it is generally 1 mm or less.

<Modification>
FIG. 10 shows an example in which the pretreatment gas 121 and the reaction gas 122 pass through the inside of the high-frequency electrode 13 and these gases are ejected into the chamber 11 from the ejection holes 131 formed on the surface of the high-frequency electrode 13. However, the present invention can also be applied when the high-frequency electrode 13 is not a shower plate type electrode as described above.

For example, as shown in FIG. 12, the pretreatment gas 121 and the reaction gas 122 are directly introduced into the chamber 11 from the gas supply mechanism 15 without passing the pretreatment gas 121 and the reaction gas 122 through the inside of the high-frequency electrode 13. May be. Also in the thin film forming apparatus 10 shown in FIG. 12, the high-frequency electrode 13 having a groove 132 formed on the surface functions as a hollow cathode electrode. That is, electrons are confined by the hollow cathode effect in the groove 132 formed on the surface of the high-frequency electrode 13, and high-density plasma is stably generated.

As in the thin film forming apparatus 10 shown in FIG. 10, various configurations can be adopted for the layout of the grooves 132 in the thin film forming apparatus 10 shown in FIG. 12. That is, the grooves 132 may be formed in a lattice shape or a stripe shape. Alternatively, long cylindrical through holes having openings on the surface of the high-frequency electrode 13 may be arranged in a lattice pattern, and these openings may be connected by grooves 132.

(Other embodiments)
As described above, the present invention has been described according to the first to third embodiments. However, it should not be understood that the description and drawings constituting a part of this disclosure limit the present invention. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art.

In the description of the first to third embodiments already described, the pretreatment gas 121 is ammonia gas, but a mixed gas of ammonia and nitrogen, hydrogen gas, or the like may be used as the pretreatment gas 121.

Even if the thin film forming apparatus 10 is an apparatus used for a semiconductor process for forming a thin film other than the plasma CVD apparatus, the passivation effect of the substrate 100 is obtained by exposing the substrate 100 to plasma containing the pretreatment gas 121. Can be increased. As a result, the carrier lifetime in the substrate 100 becomes longer and the conversion efficiency can be improved.

Thus, it goes without saying that the present invention includes various embodiments that are not described herein. Therefore, the technical scope of the present invention is defined only by the invention specifying matters according to the scope of claims reasonable from the above description.

The thin film forming apparatus of the present invention can be used for an apparatus used in a semiconductor process for forming a thin film.

Claims (8)

1. A thin film forming apparatus for forming a thin film on a substrate,
   A chamber in which the substrate is stored;
   A substrate plate disposed in the chamber for mounting the substrate;
   A high-frequency electrode disposed in the chamber and facing the substrate on the substrate plate;
   A gas supply mechanism for supplying either a pretreatment gas containing hydrogen or a reaction gas containing a raw material gas for the thin film formed on the substrate into the chamber;
   AC power is supplied between the substrate plate and the high-frequency electrode to excite either the plasma containing the pretreatment gas or the plasma containing the source gas at different stages of the film formation process on the upper surface of the substrate. A thin film forming apparatus comprising: a power source.
2. The thin film forming apparatus according to claim 1, wherein a groove is formed on a surface of the high-frequency electrode facing the substrate on the substrate plate.
3. 3. The thin film forming apparatus according to claim 2, wherein the groove is formed so as to penetrate the substrate plate.
4. 3. The thin film forming apparatus according to claim 2, wherein openings of a plurality of ejection holes through which the pretreatment gas and the reaction gas pass are formed at the bottom of the groove formed in the high-frequency electrode. .
5. The substrate is a solar cell substrate in which an n-type semiconductor layer having a surface diffusion concentration of 1 × 10 ¹⁸ to 1 × 10 ²² is formed on a p-type silicon substrate, or a surface diffusion concentration of 1 × 10 6 on an n-type silicon substrate. ^2. The thin film forming apparatus according to claim 1, wherein the thin film forming apparatus is a solar cell substrate on which ¹⁸ to 1 × 10 ²² p-type semiconductor layers are formed.
6. The thin film formed on the substrate is an antireflection film made of silicon nitride having a refractive index of 1.8 to 3.0 and a film thickness of 50 to 150 nm disposed on the solar cell. The thin film forming apparatus according to claim 5.
7. A crystal solar cell comprising an antireflection film or a passivation film formed using the thin film forming apparatus according to claim 1.
8. A semiconductor element comprising an antireflection film or a passivation film formed using the thin film forming apparatus according to claim 1.

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