JP2564753B2 - Plasma gas phase reaction method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma gas phase reaction method (hereinafter simply referred to as PCVD method). This invention is PCVD
The present invention relates to a method for forming a large amount of film by using a parallel plate type electrode system, disposing a substrate having a surface to be formed in a positive column region, and forming a large amount of film.

[0002]

2. Description of the Related Art Conventionally, in the parallel plate type PCVD method, the surface to be formed is formed on a cathode (cathode) or an anode (anode) or in a cathode dark area or an anode dark area which is generated in the vicinity of these electrodes. It is known as a method of arranging.

In such a conventionally known method, the area of the surface to be formed cannot be made larger than the area of the electrode. For this reason, the semiconductor, insulator, or conductor coating can be formed on a large-area substrate, but it cannot have a surface to be formed that is 5 to 30 times as large as the electrode area. That is, it had a drawback that mass production was not possible.

Therefore, when a non-single-crystal semiconductor containing amorphous silicon is to be produced, the production cost per 1 cm ^{2 of} the substrate is as high as 1 yen or more, and it is applied to the production of low-priced products such as solar cells. It has the major drawback of not being able to. In addition, the film formation rate is 1-2 Å
Therefore, a PCVD method having a large productivity and a large film growth rate of 3 to 10Å / second has been demanded.

[0005]

SUMMARY OF THE INVENTION The present invention aims to achieve a plasma vapor phase reaction method which has high productivity and a high film growth rate.

[0006]

In order to solve the above problems, a gas phase reaction method for forming a film on a surface to be formed by using a parallel plate type plasma glow discharge in which a pair of electrodes are arranged apart from each other. In, using a flat plate-shaped electrode having a curved surface provided with a curved surface in the opposite direction to the reaction space, a reactive gas is supplied to the reaction space through the opening or the groove, and the opening or the groove is formed. It was decided to cause the plasma gas phase reaction while concentrating the electric field in the reaction space by the groove.

That is, the method of the present invention uses a positive column of plasma glow discharge. The present invention is one in which substrates having a surface to be formed in a positive column region are arranged in parallel and spaced apart from each other. Regarding the PCVD method using such a positive column,
Patent application 57-163729, 57-163730 filed by the present inventor
(Plasma gas phase reactor) (filed September 20, 1982).

In the present invention, a reaction is caused by such a positive column,
This is a large-scale production. However, since the positive column generally spreads over a large space, the plasma density in the vicinity of the surface to be formed is reduced, and as a result, there is another drawback that the same film growth rate as in the method using the dark portion can be obtained.

By removing such a defect, the positive column is converged (stuck), that is, the spread of the discharge plasma is suppressed, the plasma density in the central portion is further increased, the active reactive gas is increased, and eventually the active reactive gas is increased. The feature is that the film growth rate is increased to 2 to 3 times.

FIG. 1 shows parallel plate electrodes (2) and (3) and their electric lines of force (5) in the conventional method, and equipotential surfaces (15) perpendicular to these lines of electric force. These electrodes are arranged in the reaction vessel (4) under reduced pressure, and the reactive gas (6) supplied from (7) is discharged from one of the electrodes and the other substrate (1) is discharged. A film is formed on the surface to be formed.

In FIG. 2 (A), 13.56 MHz is applied between the electrodes (2) and (3) from the high frequency power source (10). The unnecessary reaction product is exhausted to the outside by the exhaust system (8) through the valve (11), the pressure adjusting valve (12) and the vacuum pump (13). In such a conventional method, since the lines of electric force (5) are applied perpendicularly to the formation surface, there is another drawback that the formation surface is sputtered (damaged). Figure 1 (B)
Is a needle electrode (9) for one of the electrodes (2) in FIG. 1 (A)
Are spaced apart from each other. Here, the electrode (2) (50 cm x 50 cm), the interval between the electrodes (2) and (3) was 4 cm, the needle electrode length was 1 cm, and the interval was 5 cm. Such a needle electrode is shown in FIG.
Even when the device is arranged in the device (A), the lines of electric force are dispersed from the needle-shaped electrode and are supplied in the expanding direction, and are applied vertically to the substrate (1). The equipotential surface (15) is only provided perpendicular to the lines of electric force. Therefore, the needle-shaped electrode does not improve the film quality of the film and the film growth rate, although it has the feature of facilitating the start of discharge even when it is arranged in the device in FIG. 1 (A). It was

FIG. 2 shows an electrode in the PCVD method of the present invention and its outline. Other parts of this reactor are in accordance with the above-mentioned patent application of the present inventor. In the drawing, the pair of mesh electrodes (2) and (3) and the substrate (1) (1 ′) having the formation surface are provided. Supply of reactive gas (23)
It reaches the quartz hood (21) through the reticulated electrode (2) to reach the positive column region (5). Substrates (1) and (1 ') are arranged in the positive column region so that their back surfaces are in close contact with each other and parallel to the lines of electric force (5). The substrate is surrounded by a quartz basket. The reaction products are exhausted (24) through the lower hood (22).

High-frequency energy is externally supplied to the pair of electrodes (2) and (3) and is discharged to a region (20) where a uniform electric field is formed. In this drawing, the electrode area is 25 cmφ
(Electrode spacing 15 cm) or 70 cm x 70 cm (electrode spacing 35 cm), with a hole or groove (1
By forming 4), the first glow discharge in the equal electric field region of the present invention and the high glow second glow discharge in the opening or groove (14) were simultaneously generated. As can be seen from this figure, the lower electrode (13) is, for example, simply made with an aperture or groove (0.5-3 cm, eg about 1 cm φ or about 1 cm wide). In another example, like the upper electrode,
A curved surface (16) is provided in the opening or groove in the direction opposite to the positive column to make it concave.

As shown in FIG. 1 (B), the electric lines of force (5) converge in the regions (17) and (18) by making them not flat, that is, convex on the discharge surface, but conversely by making them flat or concave. However, it can be seen that the high-density electric flux region extends in a fibrous shape from one electrode toward the other electrode. By doing so, in addition to the first plasma discharge (27) (28) generated by the conventionally known uniform electric field, the high-intensity second plasma region ( 17) and (18) could be generated simultaneously. As a result, in the conventional case, the positive column (25) had a large lateral spread and the plasma was dispersed in the central part (20) of the electrode.
We were able to show a tendency to (35) gather within.

Further, by performing this high-intensity plasma discharge, the film growth rate could be increased 2-3 times. For example, using 100% silane, 0.1torr, 30W
(13.56MHz), when the electrode surface is 25cmφ and the electrode interval is 15cm, the substrate is 10cm and 6 sheets are arranged (total area 600cm ² ).
If there is no hole or groove (14),
The film growth rate was 1-2 Å / sec, but it is 4-6 Å only by providing several holes or grooves (14) on each electrode.
/ Sec and it became possible to increase it 2-3 times. Compared with the conventional method of FIG. 1, this means that the amount of substrates to be arranged can be increased by 5 to 20 times, and the film forming speed can be increased by 2 to 3 times, resulting in a double layer. It turns out to be excellent.

In addition, as a result of the positive columns converging, the positive columns sputter the inner wall of the reaction furnace and activate water and adhering impurities adsorbed on the inner wall and take them into the film, Considering that the possibility of degrading the film quality can be further reduced, it was found to be excellent in triplex. The present invention is complemented with the following examples.

[0017]

[Example] [Example 1] In the PCVD method using FIG.
Further, the outline of the discharge plasma is shown in FIG. The numbers correspond to those in FIG. In the drawing, three high-intensity plasma discharge regions are provided on the lower mesh electrode (3),
It is provided with four places on the upper side. The substrate (1) is arranged in a quartz holder, and this jig is rotated at 3 to 5 times / minute. Non-single-crystal silicon was produced from silane as a reactive gas. That is, substrate temperature 210 ℃, pressure 0.1 torr, silane
It has 30cc / min, discharge output of 30W, and has a thickness of 5000Å for 20 minutes, while the film growth rate is 4.1Å / sec.

Further, as is clear from the drawing, no discharge is observed in the outer space of the quartz holder in which the substrate is arranged, and there is a possibility that impurities such as water may be mixed by sputtering the stainless wall surface of the reaction vessel. You can see that there are few. Six pieces of 10 cm × 10 cm were arranged on the substrate, and the yield of the reactive gas (components forming the film / gas to be supplied, etc.) was nearly 8 times in addition to the shape as shown in FIG. Further, in FIG. 2, it was possible to double the height compared with the case where no opening or groove (14) was provided. In FIG. 3, it can be seen that no high-intensity discharge is generated in the needle electrode (9).

Example 2 Methane (CH ₄ ) and silane (Si
H ₄ ) and Si _x C _1-x (0 <x <
The coating of 1) was prepared. Compared with the case where there is no local discharge caused by the present invention, a large amount of Si—C bonds, which are silicon carbide, were formed, and a hard and dense film was formed even if chemical etching occurred. Others are the same as in the first embodiment.

As described above, according to the present invention, as shown in FIG. 2, the electrode is provided with the opening or groove, and the lines of electric force are converged in this region to generate the high-intensity discharge. In this system, when the substrate is arranged on the parallel plate electrodes as shown in FIG. 1, a part of the substrate may have a high flux reaction region. However, when considering the scatter effect due to the high-intensity discharge, it is effective to improve the film quality by disposing a surface to be formed in this discharge to reduce the spatter (damage), and as a result, the method of the present invention uses a positive column. It was found to be particularly effective for the PCVD method in which the substrate is placed parallel to the lines of electric force.

Further, the embodiment of the present invention is based on non-single crystal Si,
_X C _1-x . However, using silane and germane, Si _x
Ge (0 <x <1), Si _x Sn using silane and tin chloride
_{Even 1-x} (0 <x <1) is effective. Al to AlCl ₃
By and by a Si ₃ N ₄ and SiH ₄ and NH _3, a SiO ₂ Si
The present invention is also effective when the insulating film is formed by the PCVD method when it is formed of H ₄ and N ₂ O.

It is also possible to add B or P in addition to hydrogen or a halogen element into the semiconductor film obtained by the method of the present invention to obtain a P type or N type. In addition, the method of the present invention is also effective as a plasma vapor phase method in which ultraviolet light of 700 nm or less or infrared light of 8 μm or more is used in combination with the method of the present invention.

[0023]

INDUSTRIAL APPLICABILITY The present invention relates to a gas phase reaction method for forming a coating film on a surface to be formed by using a parallel plate type plasma glow discharge in which a pair of electrodes are arranged apart from each other, in a direction opposite to a reaction space. Using a flat plate electrode with a curved surface provided with an opening or groove, a reactive gas is supplied to the reaction space from the opening or groove, and an electric field is concentrated in the reaction space by the opening or groove. By carrying out the plasma vapor phase reaction while performing the plasma vapor phase reaction, it was possible to achieve a plasma vapor phase reaction method having high productivity and a high film growth rate.

[Brief description of drawings]

FIG. 1 shows a conventional plasma gas phase reactor.

FIG. 2 is an outline of the vicinity of an electrode substrate of the plasma vapor phase reaction apparatus of the method of the present invention.

[Explanation of symbols]

 1 substrate 2 electrode 3 electrode 14 open hole or open groove 15 equipotential surface

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hisato Shinohara 398 Hase, Atsugi City, Kanagawa Prefectural Board of Directors, Semiconductor Energy Laboratory Co., Ltd. Judge, Yasuyuki Kurachi, Yoshihiro Samura, Judge, Tadahiro Sanada

Claims (1)

(57) [Claims] At least one of the planar electrodes of 1. A pair of electrodes, the reaction space and reverse directions provided <br/> an opening or open groove having a curved surface Rutotomoni, its electrodes outside around the reaction space Reverse
A plasma gas phase reaction method characterized in that a plasma gas phase reaction is performed in the reaction space by providing a curved surface in a direction and generating plasma between a pair of electrodes.