JP2000058465A - Plasma chemical vapor deposition equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable making distribution of film thickness markedly uniform as compared with the conventional case, when high frequency power is supplied by supplying power to an electrode with a multipoint power supplying system. SOLUTION: An anode electrode 23 which involves a heater and retains a substrate 29, and a plurality of cathode electrodes 22a-22h which are arranged facing the anode electrode 23 are installed, and a multipoint power supplying system is realized by supplying electric power to the respective cathode electrodes 22a-22h via a power distributor 60 or the like. High frequency power, whose frequency is at least 30 MHz and at most 200 MHz, is supplied from a high frequency power source 24 and glow discharge is generated with the supplied power. Thereby an amorphous thin film or a fine crystal thin film or a polycrystalline thin film is formed on the surface of the substrate 29.

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma chemical vapor deposition apparatus, and a thin film used for various electronic devices such as an amorphous silicon solar cell, a thin film semiconductor, an optical sensor, and a semiconductor protective film. It is useful as a plasma chemical vapor deposition apparatus (hereinafter, referred to as a plasma CVD apparatus) applied to the production of GaN. [0002] Amorphous silicon (hereinafter a-Si)
Thin film) or silicon nitride (hereinafter, referred to as SiNx)
Two typical examples of the configuration of a plasma CVD apparatus conventionally used for producing a thin film will be described. That is, a method using a ladder-type electrode for discharge, that is, an electrode also called a ladder inductance electrode or a ladder antenna type electrode, and a method using a parallel plate electrode will be described. First, as for a method using a ladder-type electrode, Japanese Patent Application Laid-Open No. 4-236681 discloses a plasma CVD apparatus using electrodes of various shapes as a ladder-like planar coil electrode. A representative example of this method will be described with reference to FIG. Reference numeral 1 in the drawing denotes a reaction vessel, in which a discharge ladder electrode 2 and a substrate heating heater 3 are provided.
And are arranged in parallel. The discharge ladder electrode 2
, A high frequency power of 13.56 MHz, for example, is supplied from a high frequency power supply 4 via an impedance matching unit 5.
As shown in FIG. 10, one end of the discharge ladder electrode 2 is connected to the high-frequency power supply 4 via the impedance matching device 5, and the other end is connected to the ground wire 7.
And grounded. The high-frequency power supplied to the discharge ladder electrode 2 generates a glow discharge plasma between the substrate heating heater 3 and the discharge ladder electrode 2 which are grounded together with the reaction vessel 1, and passes through the discharge space. Flows to the wall of the reaction vessel 1 and to the ground via the ground wire 7 of the ladder electrode 2 for discharge. Note that a coaxial cable is used for the ground wire 7. In the reaction vessel 1, a mixed gas of, for example, monosilane and hydrogen is supplied from a cylinder (not shown) through a reaction gas introduction pipe 8. The supplied reaction gas is
It is decomposed by the glow discharge plasma generated by the discharge ladder electrode 2, held on the substrate heating heater 3, and deposited on the substrate 9 heated to a predetermined temperature. The gas in the reaction vessel 1 is passed through an exhaust pipe 10 and a
Exhausted by Hereinafter, a case where a thin film is manufactured using the above apparatus will be described. First, after the inside of the reaction vessel 1 is evacuated by driving the vacuum pump 11, a mixed gas of, for example, monosilane and hydrogen is supplied through the reaction gas introduction pipe 8,
The pressure in the reaction vessel 1 is maintained at 0.05 to 0.5 Torr. In this state, when high-frequency power is applied from the high-frequency power supply 4 to the discharge ladder electrode 2, glow discharge plasma is generated. The reaction gas is decomposed by a glow discharge plasma generated between the discharge ladder electrode 2 and the substrate heating heater 3, and as a result, Si gas such as SiH ₃ or SiH ₂ is formed.
Is generated and adheres to the surface of the substrate 9 to cause a-S
An i thin film is formed. Next, a method using parallel plate electrodes will be described with reference to FIG. Reference numeral 21 in the figure denotes a reaction vessel, in which a high-frequency electrode, that is, a cathode electrode 22, and a substrate heating heater 23 are arranged in parallel. The high-frequency electrode 22 is connected to a high-frequency power source 24 via an impedance matching unit 25 at, for example, 13.56M.
Hz high frequency power is supplied. Substrate heating heater 23
Are grounded together with the reaction vessel 21 to form a ground electrode, that is, an anode electrode. Therefore, glow discharge plasma is generated between the high-frequency electrode 22 and the substrate heating heater 23. A mixed gas of, for example, monosilane and hydrogen is supplied into the reaction vessel 21 through a reaction gas introduction pipe 26 from a cylinder (not shown). The gas in the reaction vessel 21 is exhausted by a vacuum pump 28 through an exhaust pipe 27. The substrate 29 is held on the substrate heating heater 23,
It is heated to a predetermined temperature. Using such an apparatus, a thin film is manufactured as follows. First, the inside of the reaction vessel 21 is evacuated by driving the vacuum pump 28. Next, a mixed gas of, for example, monosilane and hydrogen is supplied through the reaction gas introduction pipe 26 to maintain the pressure in the reaction vessel 21 at 0.05 to 0.5 Torr, and a voltage is applied from the high frequency power supply 24 to the high frequency electrode 22. Then, glow discharge plasma is generated. Among the gases supplied from the reaction gas introduction pipe 26, the monosilane gas is decomposed by glow discharge plasma generated between the high-frequency electrode 22 and the heater 23 for heating the substrate. As a result, radicals containing Si, such as SiH ₃ and SiH _2, are generated and adhere to the surface of the substrate 29 to form a-S
An i thin film is formed. However, the conventional techniques, that is, the method using a ladder-type electrode and the method using a parallel plate electrode all have the following problems. (1) In FIG. 9, a ladder electrode 2 for discharge is used.
The reaction gas, for example, SiH ₄ is decomposed into Si, SiH, SiH ₂ , SiH ₃ , H, H _2, etc. by the electric field generated in the vicinity, and forms an a-Si film on the surface of the substrate 9. However, if the frequency of the high-frequency power supply is increased from the current 13.56 MHz to 30 MHz to 150 MHz in order to speed up the formation of the a-Si film, the discharge ladder electrode 2
The uniformity of the electric field distribution in the vicinity is lost, and as a result, a
-The thickness distribution of the Si film becomes extremely poor. FIG. 12 shows the relationship between the plasma power supply frequency and the film thickness distribution when the substrate area is 30 cm × 30 cm. Uniformity of film thickness distribution (within ± 10%)
Is about 5 cm × 5 cm to 20 cm × 20 cm. The reason why it is difficult to increase the frequency of the high-frequency power supply 4 by using a discharge ladder electrode is as follows. As shown in FIG. 13, because of the non-uniformity of impedance due to the structure of the ladder electrode for discharge,
A portion where plasma emission is strong becomes local. For example, strong plasma is generated at the periphery of the electrode, but not at the center. In particular, the decrease becomes remarkable as the frequency becomes higher than 60 MHz. Therefore, it is extremely difficult and impossible to improve the film forming speed by increasing the frequency of the plasma power supply for a large-area substrate necessary for improving mass productivity and reducing cost. Since the deposition rate of a-Si is proportional to the square of the frequency of the plasma power supply, research has been actively conducted at academic conferences in related technical fields, but there has been no successful example of increasing the area. (2) In FIG. 11, a reaction gas, for example, SiH ₄ is converted into Si, SiH, SiH ₂ , SiH by an electric field generated between the high-frequency electrode 22 and the heater 23 for heating the substrate.
It is decomposed into H ₃ , H, H _2, etc., and a-S
An i film is formed. However, the frequency of the high-frequency power supply 24 is set to 13.
When the frequency is increased from 56 MHz to 30 MHz to 200 MHz, the uniformity of the electric field distribution generated between the high-frequency electrode 22 and the substrate heating heater 23 is lost, and as a result, a
-The thickness distribution of the Si film becomes extremely poor. FIG. 12 is a characteristic diagram showing the relationship between the plasma power supply frequency and the film thickness distribution (deviation from the average film thickness) when the substrate area is 30 cm × 30 cm. The size, that is, the area of the substrate that can ensure the uniformity of the film thickness distribution (within ± 10%), that is, 5 cm × 5 cm to 20 cm
About 20 cm. The reason why it is difficult to increase the frequency of the high-frequency power supply 24 by the method using parallel plate electrodes is as follows.
Since the parallel plate type electrode has different electric characteristics between the electrode peripheral portion and the central portion, a strong plasma is generated at the electrode peripheral portion as shown in FIG. 14 (A), or the central portion as shown in FIG. 14 (B). There is a phenomenon that strong plasma is generated only in the portion. Therefore, it is extremely difficult and impossible to improve the film forming speed by increasing the frequency of the plasma power supply for a large-area substrate necessary for improving mass productivity and reducing costs. Since the deposition rate of a-Si is proportional to the square of the frequency of the plasma power supply, research has been actively conducted in academic societies in related technical fields, but there has been no successful example of increasing the area. In view of the above prior art, the present invention uses a multi-point power supply system for the electrodes to achieve a much more uniform film thickness distribution as compared with the related art even when the supply power is increased. An object of the present invention is to provide a plasma chemical vapor deposition apparatus that can be achieved. In the present invention, the electrode has a frequency of 30 MHz.
A plurality of supply points for supplying power for generating glow discharge of 200 to 200 MHz and the power distributor, and a configuration in which impedance converters electrically connected to the power distributors are arranged, respectively, to achieve a more excellent film thickness distribution. It is an object to provide a plasma chemical vapor deposition device obtained. The structure of the present invention that achieves the above object has the following features. 1) A reaction vessel, means for introducing a reaction gas into the reaction vessel, means for discharging the reaction gas from the inside of the reaction vessel, and a heater arranged in the reaction vessel and supporting an object to be processed It has a built-in anode electrode, a plurality of cathode electrodes placed opposite to the anode electrode, and a power supply for supplying power for generating glow discharge having a frequency of 30 MHz to 200 MHz to the cathode electrode. In a plasma chemical vapor deposition apparatus that generates a glow discharge by the applied power and forms an amorphous thin film, a microcrystalline thin film, or a polycrystalline thin film on the surface of the object to be processed, a plurality of vacuums for supplying high-frequency power to the respective cathode electrodes are provided. Power supply line, and a power distributor connected to each of the cathode electrodes via each vacuum power supply line to evenly distribute the power supply. . 2) A reaction vessel, means for introducing a reaction gas into the reaction vessel, means for discharging the reaction gas from the inside of the reaction vessel, and a heater arranged in the reaction vessel and supporting the object to be processed It has a built-in anode electrode, a cathode electrode disposed opposite to the anode electrode, and a power supply for supplying power for generating glow discharge having a frequency of 30 MHz to 200 MHz to the cathode electrode. The power supplied from the power supply In a plasma chemical vapor deposition apparatus that generates a glow discharge and forms an amorphous thin film, a microcrystalline thin film, or a polycrystalline thin film on the surface of the object to be processed, a plurality of vacuum power supply lines for supplying high-frequency power to the cathode electrode A power distributor connected to the cathode electrode via each vacuum power supply line to evenly distribute the power supply; Disposed between the distributor, these have a plurality of the impedance converter which is electrically connected. 3) In the invention described in 2) above, the impedance converter is a transmission line transformer system in which a transformer formed by winding two conductors around a magnetic material and a capacitor are combined. 4) In the invention described in 2) above, the impedance converter is of a π circuit type in which variable capacitors are connected in parallel to both ends of a coil and formed as a π type as a whole. Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is an overall view of a plasma CVD apparatus according to a first embodiment of the present invention. As shown in the figure,
In the reaction vessel 21, an anode electrode 23 which supports a substrate 29 as an object to be processed, supports the substrate 29, and has a built-in substrate heating heater for controlling the temperature is arranged. In the reaction vessel 21, a plurality of high-frequency electrodes made of SUS304 for generating glow discharge plasma in a plane parallel to the substrate heating heater 23 and at a distance of 30 mm to 50 mm, that is, cathode electrodes 22a to 22h
Is arranged. Although only the upper cathode electrodes 22a to 22d are clearly shown in FIG.
a to 22d, four similar cathode electrodes 22 are provided.
e to 22h are arranged, and a total of eight sheets form the cathode electrodes 22a to 22h. In the reaction vessel 21, reaction gas introduction pipes 37, 38, and 39 for introducing a reaction gas between the cathode electrodes 22a to 22h and the substrate heating heater 23 are arranged. A vacuum pump 28 is connected to the reaction vessel 21 via an exhaust pipe 27 for exhausting a gas such as a reaction gas in the reaction vessel 21. Earth shields 40a to 40h are arranged in the reaction vessel 21. These earth shields 40a to 40h suppress discharge at unnecessary portions. The pressure in the reaction vessel 21 is monitored by a pressure gauge (not shown),
Is controlled by adjusting the displacement of the exhaust gas. When SiH ₄ plasma is generated at each of the cathode electrodes 22 a to 22 h and the anode electrode 23, radicals such as SiH ₃ , SiH ₂ , and SiH existing in the plasma are diffused by a diffusion phenomenon and adsorbed on the surface of the substrate 29. As a result, an a-Si film, microcrystalline Si, or thin-film polycrystalline Si is deposited. A known a-Si film, microcrystalline Si, or thin-film polycrystalline Si can be formed by optimizing the ratio of SiH ₄ and H ₂ raw materials, the pressure, and the power for plasma generation in the film forming conditions. Since this is a technique, an a-Si film formation using a SiH ₄ gas will be described here as an example. Of course, it is also possible to form microcrystalline Si and thin-film polycrystalline Si. Each of the cathode electrodes 22a to 22h has a coaxial cable for vacuum 43a to 43h, an impedance converter 61a to 61h, a power distributor 60,
A high frequency power supply 24 is connected via an impedance matching device 25. FIG. 2 is an electrical wiring diagram showing the electrodes and power supply of the apparatus shown in FIG. As shown in the figure, in the present embodiment, a multi-point power supply system is employed in which high-frequency power is independently supplied to each of eight cathode electrodes 22a to 22h (this number is not particularly limited). I have. That is, in the plasma CVD apparatus of the present embodiment, for example, power of a frequency of 70 MHz is
The impedance matching unit 25, the power distributor 60, and the vacuum coaxial cables 41a to 41 as a vacuum power supply line
h, the impedance converters 61a to 61h, the current introduction terminals 42a to 42d, and the cathode electrodes 22a to 22h via the vacuum coaxial cables 43a to 43h.
To the eight power supply terminals 44 to 51 welded to the power supply terminals. As shown in FIG. 3, the power distributor 60 includes a power two distributor 62 and two power four distributors 63 and 6.
4 and has a function of equally dividing the input high-frequency power into eight. The power divider 60 may be a commonly used high frequency power divider, but may also be configured by combining a 30 MHz to 200 MHz high frequency transformer, a resistor, and a capacitor. In this case, it is suitable for application to the CVD apparatus. The impedance converters 61a to 61
In order to match the impedance of the power distributor 60, the vacuum coaxial cables 43a to 43h, and the cathode electrodes 22a to 22h, two insulated conductors are provided on a ferrite annular body 65 as shown in FIG. Turn ratio is 1
What was wound and manufactured so that it might become pair 4 was used.
The equivalent circuit is as shown in FIG. As shown in the figure, the impedance converters 61a to 61h are of a transmission line transformer type combining a transformer and a capacitor. Next, a method for manufacturing an a-Si film using the plasma CVD apparatus having the above-described configuration will be described. First, the vacuum pump 28 is operated to evacuate the inside of the reaction vessel 21 and the ultimate vacuum is set to 2-3 × 10 ⁻⁷ Torr. Subsequently, a reaction gas such as Si
H ₄ gas is supplied at a flow rate of about 500 to 800 SCCM. Thereafter, the pressure inside the reaction vessel 21 is set to 0.05 to 0.5.
While maintaining at Torr, high frequency power, for example, 70 MHz, is applied to the cathode electrodes 22a to 22h from the high frequency power supply 24 via the impedance matching unit 25, the power distributor 60, the impedance converters 61a to 61h, and the vacuum coaxial cables 43a to 43h. Supply. as a result,
Glow discharge plasma of SiH ₄ is generated between the cathode electrodes 22 a to 22 h and the substrate heater 23. This plasma decomposes the SiH ₄ gas, and a-
An Si film is formed. However, the deposition rate depends on the frequency and output of the high frequency power supply 24, but is about 0.5 to 3 nm / s. Table 1 below shows that the frequency of the high-frequency power supply 24 is 70 MHz using the cathode electrodes 22a to 22h shown in FIGS. 1 and 2, and a glass substrate having an area of 40 cm × 80 cm (trade name: Corning # 7059, Corning Corporation) Production) shows the result of forming an a-Si film. Here, the film forming conditions are as follows: SiH ₄ gas flow rate 800 SCCM, pressure 0.3
Torr, 700 W of high frequency power. [Table 1] (Power frequency 70MHz, board area 40cm × 80c
m) From the data shown in Table 1, the power supply frequency is 70 MHz, the substrate area is 40 cm × 80 cm, the thickness distribution is ± 14% when there is no impedance converter, and the film thickness distribution is ± 10% when there is an impedance converter. It can be seen that good results that could not be achieved with the conventional device were obtained. In the production of a-Si solar cells, thin film transistors, photosensitive drums, etc., the film thickness distribution is ±
If it is within 10%, there is no problem in performance. According to the above embodiment, the high-frequency electrodes, that is, the cathode electrodes 22a to 22h are formed in a size of 22 cm × 22c.
m, a plurality of them are installed on the same plane, and the power is separately supplied to the vacuum coaxial cables 43a to 43h, respectively.
Impedance converters 61a to 61h, power distributor 6
By supplying the power from the high frequency power supply 24 via the zero and the impedance matching unit 25, even when using the high frequency power of 70 MHz, which has been considered difficult in the prior art, it is significantly better than the conventional apparatus and method. It has become possible to obtain a film thickness distribution. In particular, the frequency 70 of the high frequency power supply 24
In the case of MHz, a film thickness distribution of ± 10% was realized with a substrate size of 40 cm × 80 cm. This means that the industrial value related to improvement in productivity and cost reduction in the field of manufacturing a-Si solar cells, thin film transistor (TFT) driven liquid crystal displays, a-Si photoconductors, etc. is extremely large. . Incidentally, in the conventional plasma deposition apparatus,
When a high frequency power supply of 30 MHz or more is used, the film thickness distribution is extremely poor, and 30 cm × 30 cm to 50 cm × 50 c
It has not been put to practical use with a substrate having a large area of about m or more. As described above, in the first embodiment, the transmission line transformer type shown in FIGS. 4 and 5 is used as the impedance converters 61a to 61h. In this case, the output frequency of the high frequency power supply 24 is 70 M
In the case of about Hz, it is possible to realize an extremely favorable film formation state as compared with the conventional case, but it is found that when the power supply frequency is further increased, the plasma generated at a frequency of about 120 MHz becomes unstable. Was. So, 120M
As a result of repeated experiments in order to stabilize the plasma even in a high frequency region of about Hz or higher and obtain a good film formation state, the desired characteristics are obtained by adopting the π circuit method for the impedance converters 61a to 61h. It turned out to be obtained. As shown in FIG. 7, the π circuit type impedance converter is an impedance converter in which variable capacitors are connected in parallel to both ends of a coil to form an equivalent circuit as a whole, as shown in FIG. FIG. 7 shows the characteristics obtained by measuring the reflected power per 150 W of input power with the CVD apparatus when the impedance converter of the transmission line transformer type is used and when the impedance converter of the π circuit type is used. FIG. The horizontal axis in the figure is the power supply frequency, and the vertical axis is the reflected power. Referring to the figure, in the case of the transmission line transformer method,
The reflected power sharply increases from around the power supply frequency exceeding 100 MHz, whereas the π circuit
It can be seen that the reflected power is sufficiently small even if it exceeds 0 MHz. Incidentally, the smaller the reflected power, the more efficiently the power is supplied to the load. In the first embodiment, the multipoint power supply system is realized by forming the cathode electrodes with the cathode electrodes 22a to 22h divided into eight sheets. However, the present invention is not limited to this. Even when a cathode electrode is formed using a ladder-type electrode, a multipoint power supply system can be realized. In this case, the same operation and effect as those of the split cathode electrodes 22a to 22h in the first embodiment can be obtained. be able to. Therefore, a CVD apparatus using a ladder electrode will be described as a second embodiment of the present invention. FIG.
It is an electrical wiring system diagram which extracts and shows the electrode and power supply part in the CVD apparatus using a ladder type electrode. The figure is the first
This embodiment corresponds to FIG. 2 of the embodiment, and the other configuration is the same as that of the electric wiring system diagram shown in FIG. 2 except for an electrode portion. Therefore, the same parts as those in FIG. 2 are denoted by the same reference numerals, and duplicate description will be omitted. As shown in FIG. 8, the ladder-shaped electrode 70 according to the present embodiment has 8
Power supply terminals 71 to 78 are dispersedly disposed, and each of the power supply terminals 71 to 78 has an impedance matching unit 25, a power distributor 60, and an impedance converter 61.
a to 61h and vacuum coaxial cables 43a to 43h
The high-frequency power from the high-frequency power supply 24 is supplied through the respective components. Here, the impedance converters 61a to 61h may be any of the transmission line transformer system shown in FIG. 5 and the π circuit system shown in FIG.
In this respect, there is no difference from the first embodiment. For the same reason, in the case of high-frequency power of about 120 MHz or more, the π circuit type is preferable. In the second embodiment as well, the first
The a-Si film can be manufactured in the same manner as in the embodiment. The same applies to the film formation state in this case. In the first and second embodiments, the cathode electrode is configured as an aggregate of a plurality of divided small electrodes (first embodiment), and the cathode electrode is configured as a ladder-type electrode. Although the present invention relates to the second embodiment, the cathode electrode need not be limited to these. The point is that there is no particular limitation on the types of electrodes as long as power can be supplied to a plurality of points of the cathode electrode from the power supply unit of the multi-point power supply system. As described above in detail with the embodiments, according to the present invention, the discharge high-frequency electrode, that is, the cathode electrode is divided into a plurality of small-area electrodes, and each small-area electrode is divided into a plurality of small-area electrodes. It is arranged in one plane, or a multi-point feeding system using a ladder electrode having a plurality of feeding points, and an impedance matching device, a power distributor, an impedance converter, a current introduction terminal, and a vacuum for each cathode electrode. By supplying high-frequency power output from a high-frequency power supply of 30 MHz to 200 MHz via a coaxial cable, compared to the related art,
This has the effect of obtaining a good film thickness distribution with significantly improved uniformity. The above effects are not limited to the application of the a-Si thin film, but the plasma CVD technique using a high frequency power supply of 30 MHz to 200 MHz class has a use as a manufacturing method of microcrystalline Si and thin film polycrystalline Si. , Solar cells, thin film transistors, photosensitive drums, and the like have extremely large industrial utility values. When an impedance converter is provided, the film thickness distribution can be made more uniform. In addition, at this time, in a high frequency region of about 120 MHz or more, a stable plasma can be generated by using a π circuit type impedance converter, and a desired thin film in a high frequency region, which was conventionally impossible, can be formed. It can be formed with high efficiency.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a plasma CV according to a first embodiment of the present invention.
1 is an overall view of a D device. FIG. 2 is an electric wiring system diagram for supplying high-frequency power to each cathode electrode of the divided electrodes in the apparatus of FIG. FIG. 3 is an explanatory diagram of a power distributor, which is a component of the device of FIG. FIG. 4 is an explanatory diagram of a transmission line type impedance converter which is a component of the device of FIG. 1; FIG. 5 is a circuit diagram showing an equivalent circuit of FIG. 4; FIG. 6 is an explanatory diagram of a π circuit type impedance converter, which is one component of the device of FIG. 1; 7 is a characteristic diagram showing respective reflected powers with respect to a supply power frequency when the transmission line system shown in FIG. 5 and the π circuit system impedance converter shown in FIG. 6 are used. FIG. 8 is an electrical wiring system diagram for supplying high-frequency power to ladder electrodes in the device according to the second embodiment of the present invention. FIG. 9 is an overall view of a conventional plasma CVD apparatus using a ladder electrode. FIG. 10 is an electrical wiring system diagram for supplying high-frequency power to a ladder-type electrode in the device shown in FIG. 9; FIG. 11 shows a conventional plasma CVD using parallel plate electrodes.
1 is an overall view of an apparatus. FIG. 12 is a characteristic diagram showing a relationship between a plasma power supply frequency and a film thickness distribution in a conventional apparatus. FIG. 13 is a diagram for explaining non-uniformity of impedance in the conventional device of FIG. 9; FIG. 14 is a diagram for explaining a difference in electrical characteristics between a peripheral portion and a central portion of the electrode in the conventional device of FIG. 11; [Description of Signs] 21 Reaction vessels 22a to 22h Cathode electrode 23 Anode electrode 24 High frequency power supply 25 Impedance matching device 27 Exhaust pipe 28 Vacuum pump 29 Substrate (object to be processed) 37 Reaction gas introduction pipes 40a to 40h Coaxial cable (power supply line) 42a-42d Current introduction terminal 60 Power distributor 61a-61h Impedance converter 70 Ladder type electrode

Claims (1)

Claims: 1. A reaction vessel, means for introducing a reaction gas into the reaction vessel, means for discharging the reaction gas from the inside of the reaction vessel, and An anode electrode with a built-in heater for supporting a processed object, a plurality of cathode electrodes disposed opposite to the anode electrode, and a power supply for supplying glow discharge power at a frequency of 30 MHz to 200 MHz to the cathode electrode. A glow discharge generated by the power supplied from the power source to form an amorphous thin film, a microcrystalline thin film, or a polycrystalline thin film on the surface of the workpiece; And a plurality of vacuum power supply lines for supplying power, and a power distribution unit connected to the respective cathode electrodes via the respective vacuum power supply lines to evenly distribute the power supply. Plasma chemical vapor deposition apparatus characterized by comprising and. 2. A reaction vessel, means for introducing a reaction gas into the reaction vessel, means for discharging the reaction gas from the inside of the reaction vessel, and a heater arranged in the reaction vessel and supporting an object to be processed. It has a built-in anode electrode, a cathode electrode provided opposite to the anode electrode, and a power supply for supplying glow discharge power at a frequency of 30 MHz to 200 MHz to the cathode electrode. In a plasma chemical vapor deposition apparatus for generating a glow discharge and forming an amorphous thin film, a microcrystalline thin film, or a polycrystalline thin film on the surface of the object to be processed, a plurality of vacuum power supply lines for supplying high-frequency power to the cathode electrode A power distributor connected to the cathode electrode via each vacuum power supply line to evenly distribute the power supply; and Disposed between distribution device, a plasma chemical vapor deposition apparatus characterized by comprising a plurality of the impedance converter which is electrically connected thereto. 3. The method according to claim 2, wherein
A plasma chemical vapor deposition apparatus characterized in that the impedance converter is of a transmission line transformer type combining a transformer formed by winding two conductors around a magnetic body and a capacitor. 4. The invention according to claim 2, wherein
A plasma chemical vapor deposition apparatus characterized in that the impedance converter is of a π circuit type in which variable capacitors are connected in parallel to both ends of a coil and formed as a π type as a whole.