JPS63136514A - Manufacture of amorphous silicon carbide film - Google Patents

Abstract

PURPOSE:To generate an a-SiC film of desired composition by using as C- containing gas of reaction gas C2H2 gas and ethylene unsaturated hydrocarbon or saturated hydrocarbon thereby to control decomposing capacity as the C- containing gas. CONSTITUTION:In order to form, for example, an a-SiC film doped with B on a substrate 17, first, second, third and fourth regulating valves 5, 6, 7 and 8 are opened to discharge SiH4 gas, mixture gas of C2H2, CmHn (m>=1, n>=4), B2H6 gas and H2 gas from first, second, third and fourth tanks l, 2, 3 and 4, respectively. These discharging amounts are controlled by mass flow controllers 9, 10, 11 and 12, respectively to be fed through a main pipe 13 to a reaction tube 15. The tube 15 is evacuated in vacuum stage of 0.1-2.0 Torr, at 50 to 40 deg.C of substrate temperature, a high frequency power is applied to a capacity type discharging electrode 16 to generate a glow discharge. Thus, the gas is decomposed to form a B-containing a-SiC film on the substrate at a high speed. Thus, since the C amount of the a-SiC film can be freely varied, the a-SiC film of desired characteristics can be formed.

Description

[Detailed Description of the Invention] [Field of the Invention] The present invention relates to a method for manufacturing an amorphous silicon carbide film, and more particularly to a method for manufacturing an amorphous silicon carbide film that facilitates the handling of raw material gas and the control of film quality. .

[Prior art]

In recent years, in addition to semiconductors made of single crystal materials, semiconductors made of three amorphous films have attracted attention, and their use as photoelectric conversion elements such as solar cells or photoreceptors for electrophotography is being actively carried out. .

The semiconductor material is amorphous silicon (A-5
i) or amorphous silicon carbide (a-3
iC) is attracting attention, and in particular a-3iC has a larger band gap than a-3i and has excellent heat resistance, thermal shock resistance, and abrasion resistance, so it is suitable for photoreceptors, light emitting materials,
Applications as light-receiving elements are being advanced.

This 3-5iC film is produced, for example, by a glow discharge decomposition method, and the production gas is methane, ethane, propane,
C (carbon)-containing gases such as ethylene, and Si (silicon)-containing gases such as silane, disilane, trisilane, and silicon tetrafluoride are used.

However, when a-3iCpIi is formed using the above gas, it is produced only at a low film formation rate of 1 μm/h or less, and for practical use, for example, in the production of electrophotographic photoreceptors, which require a high film formation rate. Approximately 5 to 30
Since a thickness of μm is required, it is desired to improve the film formation rate.

In response to such demands, the present inventors have found that a significantly high film formation rate can be obtained by using acetylene (C2H□) as the C-containing gas, and it is possible to apply the a-3iC film as a photoreceptor. It was suggested.

[Problem that the invention seeks to solve]

However, when C211□ gas is supplied into the reaction tube as a raw material gas, Cz! A high-pressure sealed cylinder can be used for Iz gas, but due to the nature of CZH2 itself, highly purified 0211
Since these materials have decomposition and explosive properties, it is necessary to take great care when handling them, and there are problems in terms of manufacturing efficiency. In other words, the filling pressure of the cylinder is 0゜5Kg/cm"
Therefore, the pure amount of gas per cylinder is much smaller than that of other C-containing gases, and the cylinders must be replaced frequently, reducing efficiency.

In addition, when forming a-SiC film, C211□ gas is
Although it has a high resolution compared to the contained gas, it is difficult to adjust the flow rate, and the produced a-5iC film itself C
There is a problem that the amount tends to increase, making it difficult to obtain a highly modified a-5iC film having a desired composition.

[Means for solving problems]

As a result of repeated research into the steam problem, the present inventors found that CZI! □ By using gas and ethylenically unsaturated carbon hydrogen or saturated carbon hydrogen, the decomposition and explosiveness of cznz under high pressure can be suppressed, making it possible to easily handle the reaction gas and reducing the C2H per book
Since the pure amount of the two gases can be increased, production efficiency can be improved, and the a-5iC film produced by controlling the resolution of the C-containing gas and making it easier to adjust the flow rate. The inventors have discovered that it is possible to improve the film quality and produce an a-SiC film with a desired composition, leading to the present invention.

The present invention will be explained in detail below.

According to the production method of the present invention, at least a Si-containing gas and a C-containing gas are used as the reaction gas,
A major feature of the present invention is that a mixed gas of CzHz gas and CmHn (where m≧1, n≧4) gas is used as the C-containing gas.

Specifically, the CmHn gas is preferably an ethylenically unsaturated hydrocarbon or a saturated carbon hydrogen gas which itself is a gas at room temperature, such as CzH6, C3! (a, CtH
+. +C3HI□, CzH4, CJ6. CtHa+Cs
11. . Examples include linear chains represented by the following and isomers thereof.

The ratio of C2H2 gas and CmHn gas is (CmHn/Cz
llz + Cmtln) ratio of 0.1 to 0.9, particularly 0.3 to 0.8; if this ratio is less than 0.1, it will be difficult to achieve the purpose of the present invention; if it exceeds 0.9, C2
High-speed film formation using H gas becomes impossible.

In addition, for the purpose of suppressing the decomposition and explosiveness of C2H2 under high pressure, this C-containing gas must always be mixed with C2H2 and CmHn gas and sealed at high pressure when sealed in a cylinder, etc. .

As the Si-containing gas, SiII 4+ Si t
Hb etc. can be used, and this Si-containing gas is C-containing gas:Si-containing gas・0.
It is preferable to blend in a ratio of 0.01:1 to 3:l, particularly 0.01:1 to 1:l.

According to the manufacturing method of the present invention, various gases can be mixed in addition to the above-mentioned C-containing gas and Si-containing gas,
For example, for the purpose of terminating the generated a-5iC dangling bond, +1. F.

A gas containing a monovalent element such as CI can be introduced.

After these reaction gases are introduced into the reaction system, they are decomposed by energy supply means such as heat, light, DC glow discharge, high frequency glow discharge, microwave plasma, etc., and a-5iC or a- Generate as SiC:)I. Specifically, a-3iC generated from use as a semiconductor is 5i(1-X, CM...(1) However, 0.01≦X≦0.9, especially 0.05≦X≦0.
It is represented by 5.

According to the manufacturing method of the present invention, various elements can be doped to change the characteristics of the a-3iC film depending on the use as the a-3iC. The a-5iC film itself is a weak n-type semiconductor, and contains elements of Group Va of the periodic table such as P, N, As, and Sb. It is possible to further strengthen the n-type by doping in a range of OOOppm or less, and conversely, it is possible to strengthen the n-type by doping in the range of OOO ppm or less, and conversely,
group elements from 0.1 to 10. It can be made into a P-type semiconductor by doping in the range of OOOppm.

In such a case, a gas containing each doping element in the reaction gas, for example, 82+1. , BF3. At(Cll3):+,G
a(Cll:+) 3In(CH3)z etc. is contained in the reaction gas at a ratio of 10-b to 1 mol χ, especially 10-5 to 0.1 mol χ, and also contains Group Va elements of the periodic table. PHi+Nz+Ast13+AsF3,5bF as gas
ff etc. in the reaction gas at 1 mol% or less, especially 0°1 mol%
It may be contained in the following proportions.

Next, a case in which a high frequency glow discharge decomposition method is adopted as an embodiment of the manufacturing method of the present invention will be described in detail.

FIG. 1 is a diagram for explaining a capacitively coupled glow discharge decomposition device used in one embodiment. Note that boron was selected as the doping element.

In the diagram, 1st, 2nd, 3rd, and 4th tanks (1) (2)
(3) and (4) respectively contain S i H, gas, and BzHb.
Gas, 112, C, H2 gas and CmHn gas are mixed in the above-mentioned ratio and are compressed and sealed.
is also used as a carrier gas. These gases are controlled by the corresponding first, second, third, and fourth regulating valves (5) (6)
(7) It is released by opening (8), and its flow rate is adjusted to the mass flow controller (9) (10) (1
1) Main pipe (13) controlled by (12)
sent to. Note that (14) is a stop valve.

The gas flowing through the main pipe (13) flows through the reaction tube (1
A capacitively coupled discharge electrode (16) is installed inside this reaction tube, and the power applied to this is 50-3 KW, and the frequency is IMH.
2 to 10 MIIz is suitable. Inside the reaction tube (15), a cylindrical conductive substrate for film formation (17) made of aluminum is placed on a sample holding table (18).
This holding table (18) is rotatably driven by a motor (19), and the substrate (17) is heated to about 50 to 400°C, preferably about 1°C, by suitable heating means.
It is heated uniformly to a temperature of 50 to 300°C. Furthermore, the inside of the reaction tube (15) is kept in a high vacuum state (discharge voltage 0.1 to 2.0 To
rr) is connected to the rotary pump (20) and the diffusion pump (21).

In the gummy discharge decomposition device configured as above,
For example, a B-doped a-3iC film is used as a substrate (17
), open the first, second, third, and fourth regulating valves (5), (6), (7), and (8) to form the first, second, third, and fourth tanks (1). (2) (3) (4)
S i II 4 gases, CzHz and Cmt, respectively.
1n mixed gas, B 2tl b gas, and 11□ gas are released, and the amount of these emissions is controlled by a mass flow controller (9
) (10) (11) (12) and is fed into the reaction tube (15) via the main pipe (13), and the inside of the reaction tube (15) is regulated by 0.1 to 2.
QTorr vacuum state, substrate temperature 50 to 400°
Frequency 1 to 10 M to C5 capacitive discharge electrode (16)
II Z high frequency power of 50 W to 3 KW is applied, a glow discharge occurs, the gas decomposes, and B
A containing a-3iC film is formed on the substrate at high speed.

Note that the manufacturing method of the present invention is not limited to the above-mentioned high-frequency glow discharge decomposition method, and high-speed film formation can be similarly achieved even if other film-forming methods are employed. Examples include chemical vapor deposition methods such as optical CVD, laser CVD, thermal CVD, direct current glow discharge decomposition, microwave plasma CVD, and ECR plasma CVD. By introducing the same composition ratio into the system and decomposing it, an a-3iC film can be produced at high speed.

The invention will now be explained with the following examples.

Example An aluminum cylindrical drum for a substrate finished to a mirror finish using an ultra-precision lathe using a diamond cutting tool was subjected to ultrasonic cleaning and steam cleaning using an organic solvent, and then dried.
The reaction tube (1
5) It was installed inside.

Then, 5illa gas from the first tank (1), 82H gas from the second tank (2), 11 gas from the third tank (3)
CzHz and Cmtln mixed in the proportions shown in Table 1 were discharged from the fourth tank (4) at the flow rates shown in Table 1, and the gas pressure was reduced to 0.5 Torr.
, set the high frequency power to 100W and the substrate temperature to 3.
When a film was formed for 1 hour based on the glow discharge decomposition method described above at a temperature of 00°C, a P-type a-5i film with excellent film quality was obtained.
A C:H;B film was obtained. And the obtained a-3iC:)
The thickness of the l:II film was measured.

[Margin below]

[Effects of the Invention] As detailed above, according to the method for producing an amorphous silicon carbide film of the present invention, C2 is used as the carbon-containing gas.
By using a mixture of H2 gas and CmHn gas (m≧1, n≧4), the decomposition and explosiveness of C,11 gas under high pressure can be alleviated, thereby making the gas easier to handle. In addition, it is possible to increase the pure amount of C211□ gas per cylinder, reducing the frequency of cylinder replacement and improving manufacturing efficiency. a-3i
It becomes possible to control the film formation speed when forming a C film at high speed, and in particular, it is possible to freely change the Ci of the produced a-5iC film, so that it is possible to form a-SiC with desired characteristics.
membrane can be obtained. This manufacturing method is applicable to all kinds of light-emitting elements and light-receiving elements, including electrophotographic photoreceptors, which require high-speed film formation and a-SiC films with various characteristics.

[Brief explanation of the drawing]

FIG. 1 is a diagram for explaining a capacitively coupled glow discharge decomposition device used in one embodiment of the present invention. 1.2, 3.4 Tank 15 Reaction tube 17 Substrate

Claims (1)

[Claims] In a method for producing an amorphous silicon carbide film in which at least a Si-containing gas and a C-containing gas are used as raw material gases and are decomposed to deposit amorphous silicon carbide on a substrate, C_2H_2 is used as the C-containing gas.
A method for producing an amorphous silicon carbide film characterized by using a gas and a C_mH_n (m≧1, n≧4) gas.