JPH0627337B2 - Deposited film forming apparatus by plasma CVD method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a deposited film on a substrate, particularly a functional film, particularly a semiconductor device, a photosensitive device for electrophotography, a line sensor for image input, and an imaging device. , Optimum plasma CVD for forming non-single crystalline deposition film such as amorphous or polycrystalline used for photovoltaic devices
Regarding the device.

[Description of Prior Art]

Conventionally, semiconductor devices, photosensitive devices for electrophotography,
As an element member used for a line sensor for image input, an imaging device, a photovoltaic element, etc., for example, an amorphous film containing silicon (hereinafter simply referred to as “a-Si”) film or silicon hydride is contained. Amorphous (hereinafter simply referred to as "a-SiH") films and the like have been proposed, and some of them are put to practical use. There have also been proposed several methods for forming such a-Si films and a-SiH films, as well as methods for forming such a-Si films and a-SiH films, and apparatuses for carrying them out, such as vacuum deposition and ion plating. Law,
There are so-called thermal CVD method, plasma CVD method, optical CVD method, etc. Among them, the plasma CVD method is put to practical use as an optimum method, and is generally widely used.

By the way, in the plasma CVD method, the deposited film forming gas is excited and seeded (radicalized) in the vicinity of the substrate surface by utilizing direct current, high frequency or microwave energy to cause a chemical interaction, and the substrate surface is exposed. It is to deposit a film, and various devices have been proposed for that purpose.

FIG. 2 is a schematic cross-sectional view showing a typical example of a conventional deposited film forming apparatus by the plasma CVD method.
Reference numeral 1 denotes the entire reaction vessel, 2 is a cathode electrode which also serves as a side wall of the reaction vessel, 3 is an upper wall of the reaction vessel, and 4 is a bottom wall of the reaction vessel. The cathode electrode 2, the upper wall 3 and the bottom wall 4 are insulated by an insulator 5, respectively.

Reference numeral 6 denotes a cylindrical substrate provided in the reaction vessel, and the cylindrical substrate 6 is grounded to serve as an anode electrode.
A heater 7 for heating a substrate is installed in the cylindrical substrate 6, and the substrate is heated to a set temperature before film formation, the substrate is maintained at the set temperature during film formation, or after film formation. It is used to anneal the base. The cylindrical substrate 6 is connected to the rotation driving means 8 via a shaft, and rotates the cylindrical substrate 6 during film formation.

Reference numeral 9 denotes a deposition film forming raw material gas discharge pipe provided on the coaxial outer circumferential circle of the cylindrical base member 6 along the longitudinal direction of the cylindrical base member 6, and each of the gas discharge pipes 9, 9 ... A large number of gas discharge holes 9a, 9a, ... Are provided for discharging the source gas toward the side wall of the reaction vessel. Further, the raw material gas supply system 20 for forming a deposited film is communicated with each other through the raw material discharge pipes 9, 9 ... And a gas introduction pipe 10 having a valve 11.

The raw material gas supply system 20 for forming a deposited film includes gas cylinders 201 to 205 in which a raw material gas for forming a deposited film is sealed, and a gas cylinder 20.
1 to 205, valves 211 to 215, mass flow controllers 221-225, inflow valves 231-235 to the mass flow controller, outflow valves 241-245 from the mass flow controller, and gas pressure regulator 251-2. twenty five
It starts from 5.

Reference numeral 12 denotes an exhaust pipe for evacuating the inside of the reaction vessel, and a vacuum exhaust device (not shown) via an exhaust valve 13.
Is in communication with.

Reference numeral 14 is a means for applying a voltage to the cathode electrode 2.

The operation of the conventional deposited film forming apparatus by the plasma CVD method is performed as follows. That is, the gas in the reaction vessel is evacuated through the exhaust pipe 12, the cylindrical substrate 6 is heated and held at a predetermined temperature by the heater 7 for heating, and further rotated by the rotation driving means 8. Next, for example, in the case of forming an a-SiH deposited film through the raw material gas introducing pipe 9, a raw material gas such as silane is introduced into the reaction vessel, and the raw material gas is released from the gas introducing pipe. It is emitted from the holes 9a toward the surface of the substrate. Simultaneously with this, for example, a high frequency is applied from the voltage applying means 14 between the cathode electrode 2 and the base body (ash electrode) 6 to generate plasma discharge. Thus, the raw material gas in the reaction vessel is excited to generate excited species, and radical particles such as Si ^* , SiH ^*, etc. (* represents an excited state), electrons, ion particles, etc. are generated, and these react with each other. A- on the surface of the cylindrical substrate
A deposited film of SiH is formed.

Although the above-described conventional deposited film apparatus by the plasma CVD method is widely used as an optimum apparatus, it has some problems as follows.

That is, in forming a deposited film by the plasma CVD method, it is known that the gas pressure, gas flow rate, input power, etc. of the source gas introduced into the reaction space affect the film quality and film thickness of the formed film. In order to form a deposited film having a uniform thickness and film quality, the distribution of the source gas released from the source gas release hole 9a of the gas introduction pipe 9 into the reaction space is an important factor. In the conventional apparatus as shown in the figure, since the peripheral wall (cathode electrode 2) of the reaction vessel is cylindrical, the source gas released from the source gas release holes 9a, 9a ... And the discharge formed in the reaction vessel. There is a problem that it is difficult to mix with plasma uniformly.

This point will be described with reference to FIG. 3 showing a cross section of the reaction vessel of the conventional apparatus shown in FIG. In the figure, 2 is the peripheral wall of the reaction container (cathode electrode), 6 is a cylindrical substrate (anode electrode), 9 is a source gas discharge pipe, and arrows show the flow of source gas. The raw material gas discharged toward the peripheral wall 2 from the gas discharge holes 9a, 9a ... Provided in the raw material gas discharge pipes 9, 9 ... Is rectified and flows because the peripheral wall 2 has a cylindrical shape. The gas and the discharge plasma are not uniformly mixed, and as a result, the film thickness and film quality of the formed deposited film vary in the circumferential direction of the cylindrical substrate.

Such a problem can be solved to some extent by rotating the cylindrical substrate 6 by the rotation driving means 8, but it cannot be said to be complete. Further, the installation of such rotation driving means 8 complicates the apparatus itself, and the apparatus design. There is also a problem that the above-mentioned unreasonableness increases.

By the way, the above-mentioned various devices have been diversified, and it is a social requirement to form a deposited film having various wide characteristics as an element member therefor and, in some cases, to form a deposited layer having a large area. Therefore, in order to develop an apparatus capable of steadily mass-producing a deposited film that meets these requirements, the distribution of the source gas in the reaction space is adjusted to achieve uniform film thickness and film quality of the formed deposited film. The problem is becoming more serious.

[Object of the Invention]

The present invention solves the above-mentioned problems and solves the above-mentioned demands with respect to a conventional apparatus for forming a deposited film used for a photovoltaic device, a semiconductor device, an image input line sensor, an imaging device, an electrophotographic photosensitive device, and the like. The purpose is to satisfy.

That is, the main object of the present invention is to improve the productivity of the film while at the same time making the film thickness, film quality and various characteristics of the film to be formed, in particular, enabling mass production, and at the same time increasing the area of the film. It is an object of the present invention to provide a deposited film forming apparatus by the plasma CVD method that enables the deposition.

Another object of the present invention is a plasma CV which has a simple apparatus configuration and can efficiently mass-produce deposited films having various characteristics.
It is to provide a deposited film forming apparatus by the D method.

[Constitution and effect of the invention]

The inventors of the present invention have earnestly studied to achieve the above-mentioned object by overcoming the above-mentioned problems of the conventional deposited film forming apparatus by the plasma CVD method, and as a result, the surrounding wall ( By making the shape of the cathode electrode) 2 into a shape in which the raw material gas diffuses, the above-mentioned problems are solved,
Moreover, the inventors have obtained the knowledge that the above-mentioned object can be achieved, and completed the present invention.

The deposited film forming apparatus by the plasma CVD method of the present invention includes a reaction container hermetically formed by an upper wall, a peripheral wall and a bottom wall,
A means for placing a cylindrical substrate in the reaction vessel, a deposition gas forming source gas discharge pipe provided on a coaxial outer circumferential circle of the cylindrical substrate along the longitudinal direction of the cylindrical substrate, and the source gas What is claimed is: 1. A deposited film forming apparatus by a plasma CVD method, comprising: a means for applying discharge energy for exciting to generate excited species; and a means for exhausting the inside of the reaction vessel, wherein the cylindrical shape is formed on a peripheral wall of the reaction vessel. The essence is that a plurality of recesses are provided along the longitudinal direction of the substrate, the source gas is discharged toward the recesses, and the source gas is diffused in a turbulent state.

Hereinafter, the apparatus of the present invention will be described in detail with reference to the drawings, but the present invention is not limited to the embodiments.

The apparatus of the present invention is the same as the conventional apparatus shown in FIG.

1 (A) to (C) are schematic cross-sectional views schematically showing a typical example of the shape of the peripheral wall in the device of the present invention. In the figure, 2 is a peripheral wall, 6 is a cylindrical substrate, 9 is a gas discharge pipe, and arrows show the flow of raw material gas.

In the apparatus of the present invention, the peripheral wall 2 of the reaction vessel is
By making the shape as shown in (A) to (C),
Since the raw material gas released from the gas release hole 9a under the gas release 9 becomes a turbulent flow as shown by the arrow, the raw material gas and the discharge plasma are uniformly distributed in the reaction vessel, and as a result, the surface of the cylindrical substrate is The film thickness and film quality of the deposited film formed are uniform in the circumferential direction of the cylindrical substrate.

The peripheral wall having the above-mentioned shape of the device of the present invention can be formed by various known methods, one of which is an extrusion molding method.

The source gas used for forming the deposited film by the apparatus of the present invention is of a type that excites species by high frequency or microwave energy and chemically interacts to form a desired deposited film on the substrate surface. Any one can be used as long as it is, for example, when forming an a-Si film, specifically, silanes in which hydrogen, halogen, hydrocarbon or the like is bonded to silicon. In addition, it is possible to use those in a gas state such as halogenated silanes, or gasified substances that can be easily gasified. These source gases may be used alone or in combination of two or more. Also, these source gases are He
It may be used after diluting with an inert gas such as Ar, Ar. Furthermore, the a-Si film can be doped with a P-type impurity element or an n-type impurity element, and a source gas containing these impurity elements as constituents is used alone.
Alternatively, it can be mixed with the above-mentioned raw material gas and / or the diluting gas and introduced into the reaction space.

The substrate may be conductive, semi-conductive, or electrically insulating, and specific examples thereof include metals, ceramics, and glass. The substrate temperature during the film forming operation is not particularly limited, but it is generally in the range of 30 to 450 ° C, and preferably 50 to 350 ° C.

Further, in forming the deposited film, it is preferable that the reaction space of the apparatus of the present invention is under a reduced pressure condition, but it may be a normal pressure condition and, in some cases, a pressurized condition. You can also When forming a deposited film under reduced pressure, the pressure in the reaction space before introducing the source gas is set to 5 × 10 ^-6 Torr or less, preferably 1 × 10 ^-6 Torr or less, and the reaction space is set when the source gas is introduced. It is desirable to set the internal pressure to 1 × 10 ^-2 to 1 Torr, preferably 5 × 10 ^{-1 to 1} Torr.

〔Example〕

Examples in which the apparatus of the present invention is operated to form a deposited film will be described below, but the present invention is not limited thereto.

In this example, the reaction vessel 1 of the plasma CVD apparatus shown in FIG. 2 is a reaction vessel having a peripheral wall (cathode electrode) 2 having a cross-sectional shape shown in FIG. A light-receiving layer including an injection blocking layer, a photosensitive layer and a surface layer was formed. The size of the device in this example is as follows.

In addition, the gas cylinder 201 is SiH ₄ gas and the gas cylinder 202.
The gas cylinder 203 was sealed with B ₂ H ₆ gas, the gas cylinder 203 was sealed with NO gas, the gas cylinder 204 was sealed with CH ₄ gas, and the gas cylinder 205 was sealed with H ₂ gas.

First of all, close all the valves 211 to 215 of the gas cylinder and the valves 231 to 235 and 241 to the other gas supply system 20.
245, 11 and the exhaust valve 13 were opened to reduce the pressure in the reaction vessel 1 to 10 ^-7 Torr. At the same time, the Al cylinder 6 was heated to 250 ° C. by the heating heater 7 and kept constant at 250 ° C. When the temperature of the Al cylinder is stable, all of the inflow valves 231-235, the outflow valves 241-245 and the valve 11 are closed, and the valve of the gas cylinder 205 is closed.
Open 215 and mass flow controller 225 to 300 SCCM
Set to inflow valve 235, outflow valve 245 and valve
11 was sequentially opened and H ₂ gas was introduced into the reaction vessel 1.

Next, SiH ₄ gas in gas cylinder 201 and B ₂ H in gas cylinder 202
₆ gas and NO gas in the gas cylinder 203 were sequentially introduced into the reaction vessel 1 by repeating the same operation as described above. The flow rates of SiH ₄ gas, B ₂ H ₆ gas, and NO gas are
The SiH ₄ gas was set at 150 SCCM, the B ₂ H ₆ gas was set at 1600 Vol ppm with respect to the SiH ₄ gas flow rate, and the NO gas was set at 3.4 Vol% with respect to the SiH ₄ gas flow rate.

When the flow rate of each gas becomes stable, the exhaust valve 13
Is adjusted so that the pressure in the system becomes 0.2 Torr, and when the pressure in the system becomes stable, high-frequency discharge (13.56 MHz, 150 W) is generated using the voltage applying means 14, and the film thickness of a- A charge injection blocking layer composed of Si: H: B: O was formed.

Next, a photosensitive layer made of a-Si: H having a film thickness of 20 μm was formed in the same manner as described above except that the inflow of B ₂ H ₆ gas and NO gas was stopped.

Furthermore, the amount of SiH ₄ gas was set to 35 SCCM, and the flow rate of CH ₄ gas was changed to SiH ₄
All were the same as above, except that SiH ₄ / CH ₄ = 1/30 was set for the gas flow rate.
i: A surface layer made of C (H) was formed.

Finally, all the gas valves were closed, the discharge and heating heaters were stopped, the inside of the reaction vessel was evacuated, the temperature of the Al cylinder was lowered to room temperature, and the formed light receiving member was taken out of the system.

Regarding the obtained light receiving member, the film thickness and the film potential are
Eight points in the circumferential direction of the center of the manufactured cylinder (No. 1 (A)
The measurements were made in FIGS. A, B, A, B ...). The results are shown in Table 1 below. The membrane potential is the surface potential of the membrane when it is mounted on a copier (NP-9030) manufactured by Canon Inc. as a photosensitive drum and subjected to corona charging of 7.5 KV.

Next, as Comparative Example 1, a light receiving member was formed under the same conditions as described above except that a reaction container (conventional device) having a cross-sectional shape shown in FIG. 3 was used. The size of the device in the comparative example is as shown below.

Further, as Comparative Example 2, a deposited film was formed under the same conditions as in Comparative Row 1 described above except that the Al cylinder 6 was rotated.

Regarding the light receiving members obtained in Comparative Examples 1 and 2, Example 1
The film thickness and the film potential were measured in the same manner as above, and the results shown in Table 1 below were obtained.

From the results shown in Table 1, the results obtained by the conventional apparatus were
When the manufacturing cylinder is not rotated, the unevenness in the film thickness and the film quality becomes large in the circumferential direction, whereas when the device of the present invention is used, the unevenness in the film thickness and the film quality in the circumferential direction is significantly improved even when the rotation is not performed. You can see that it is done.

[Brief description of drawings]

FIGS. 1 (A) to (C) are schematic cross-sectional views showing typical examples of the shape of the peripheral wall in the deposited film forming apparatus by the plasma CVD method of the present invention. FIG. 2 is a schematic cross-sectional view schematically showing a typical example of a conventional deposited film forming apparatus by the plasma CVD method, and FIG. 3 is a schematic cross-sectional view showing the shape of a peripheral wall in the conventional apparatus. Regarding FIGS. 1 to 3, 1 ... Reactor container, 2 ... Peripheral wall also serving as a cathode electrode,
3 ... Top wall, 4 ... Bottom wall, 5 ... Insulator, 6 ... Cylindrical substrate, 7 ... Heating heater, 8 ... Rotation drive means, 9 ...
… Gas inlet pipe, 9a …… Gas outlet, 10 …… Gas supply pipe,
11 ... Valve, 12 ... Exhaust pipe, 13 ... Exhaust valve, 14 ...
… Voltage applying means, 20 …… Source gas supply system for forming deposited film,
201-205 …… Gas cylinder, 211-215 …… Valve, 22
1 to 225 …… Masflo controller, 231-235 ……
Inflow valve, 241-245 ... Outflow valve, 251-255 ...
… Gas pressure regulator

Claims (1)

[Claims] 1. A reaction vessel hermetically formed by an upper wall, a peripheral wall and a bottom wall, a means for installing a cylindrical substrate in the reaction vessel, and a cylindrical substrate on a coaxial outer circumference of the cylindrical substrate. A deposition film forming raw material gas discharge pipe provided along the longitudinal direction of the, a means for applying discharge energy for exciting the raw material gas to generate excited species, and a means for exhausting the inside of the reaction vessel. And a plurality of recesses provided along the longitudinal direction of the cylindrical substrate on the peripheral wall of the reaction vessel, wherein the source gas is discharged toward the recesses. An apparatus for forming a deposited film by a plasma CVD method, characterized in that a gas is diffused in a turbulent state.