JP2008294465A - Current inlet terminal, plasma surface treatment device with current inlet terminal and plasma surface treatment method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a plasma surface treatment device and a plasma surface treatment method for preventing power loss and realizing large area/uniform plasma surface treatment, by restricting plasma generation and abnormal discharge at positions other than between a pair of electrodes with respect to plasma generation in VHF band and its application to plasma surface treatment. <P>SOLUTION: In a current inlet terminal, one end of two rectangle sheet-shaped conductors 61, 62 insulated mutually with dielectric body and installed in a tube-like conductor 60 which passes through a wall of a vacuum container 1 and arranged at the wall, is arranged on a vacuum side and the other end is on the side of atmosphere, and at the same time, one end of the tube-like conductor 60 and a ground shield box 66 of a balance/unbalance conversion unit are contacted tightly. In addition, the plasma surface treatment device having the current inlet terminal and the plasma surface treatment method having the current inlet terminal are provided. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a surface treatment apparatus and a surface treatment method for performing a predetermined treatment on a surface of a substrate using plasma. In particular, the present invention relates to a surface treatment apparatus using an ultrahigh frequency plasma having a low electron temperature and capable of generating a high density plasma, that is, a plasma generated by a high frequency power having a frequency in the VHF band (30 MHz to 300 MHz) and The present invention relates to a surface treatment method.

  Various kinds of processing are performed on the surface of the substrate using plasma to manufacture various electronic devices, such as LSI (Large Scale Integrated Circuit), LCD (Liquid Crystal Display) TFT (Thin Film Transistor), amorphous silicon solar cell and microcrystal. It has already been put into practical use in fields such as silicon solar cells.

In recent years, as one of the important needs regarding a plasma surface treatment apparatus and a plasma surface treatment method, application to the production of thin film silicon solar cells is increasing.
In the field of thin-film silicon solar cells, integrated tandem thin-film solar cells combining amorphous silicon and microcrystalline silicon have attracted attention, and are expected to be put into practical use for their full-scale spread.
Integrated tandem thin-film silicon solar cells have a transparent electrode layer, an amorphous silicon photoelectric conversion unit layer, and a function of reflecting short-wavelength light and transmitting long-wavelength light onto a light-transmitting substrate (for example, glass). Is formed by sequentially laminating an intermediate layer, a crystalline silicon photoelectric conversion unit layer, and a back electrode layer.
The amorphous silicon photoelectric conversion unit layer is composed of a p-type semiconductor layer, an i-type semiconductor layer, an n-type semiconductor layer, and the like, and the thickness of the entire pin layer is about 0.3 μm.
The crystalline silicon photoelectric conversion unit layer is composed of a p-type microcrystalline semiconductor layer, an i-type microcrystalline semiconductor layer, an n-type microcrystalline semiconductor layer, etc., and the thickness of the entire pin layer is about 2.5 to 5 μm. . Note that the i-type microcrystalline semiconductor layer has a thickness of about 2 to 4 μm.
The production line for manufacturing solar cells combining amorphous silicon and crystalline silicon called so-called integrated tandem thin-film solar cells is expected to be able to manufacture high-efficiency modules with a photoelectric conversion efficiency of 10 to 13%. ing.

However, the integrated tandem-type thin film solar cell has the merit that the photoelectric conversion efficiency can be easily improved, but the i-type microcrystalline semiconductor of the crystalline silicon photoelectric conversion unit layer that requires a thickness of about 2 to 4 μm. A great deal of time is required to produce the layer. Therefore, it is necessary to install a plurality of i-type microcrystalline semiconductor layer manufacturing apparatuses, which has a demerit that production cost increases.
In recent years, in order to eliminate this disadvantage, development of a technique for improving the deposition rate of an i-type microcrystalline semiconductor layer and development of a plasma CVD apparatus capable of manufacturing a large area with high quality and good uniformity have been carried out. It has been broken.
Recently, as a technique for improving the film forming speed of the i-type microcrystalline semiconductor layer, a VHF (very high frequency band: 30 MHz to 300 MHz) plasma CVD apparatus is used, and as a film forming condition, it is diluted with a large amount of hydrogen. This can be realized by using silane gas (SiH4) and supplying high power at high pressure.
However, the development of a plasma CVD apparatus that can be manufactured with a large area, good uniformity, and high quality still has many problems and is in a state of frustration.

Non-Patent Document 1 discloses a technique relating to high-quality and high-speed film formation of a crystalline i-layer film for an integrated tandem-type thin film solar cell by VHF plasma CVD using parallel plate electrodes.
That is, as experimental conditions, the size of parallel plate electrodes: diameter 10 cm, source gas: high hydrogen diluted SiH4, pressure: 2-4 Torr (133-532 Pa), substrate temperature: 250 ° C., power supply frequency: 60 MHz, input power: film formation It is shown that high-quality microcrystalline Si can be obtained by setting the speed to 2.54 W / cm 2 at a speed of 1.7 nm / s and 3.4 W / cm 2 at 2.5 nm / s.
It has also been shown that high-quality microcrystalline Si can be obtained by using VHF plasma CVD with a frequency of 60 MHz even under high-speed film forming conditions of 1.7 to 2.5 nm / s.
The input power is 2.54 W / cm 2 when the film forming speed is 1.7 nm / s, and 3.4 W / cm 2 when the film forming speed is 2.5 nm / s, which means that very large power is required. For example, in the case where the substrate area is 110 cm × 140 cm (15400 cm 2), if proportional calculation is simply performed, 39.1 kW is necessary when the film forming speed is 1.7 nm / s, and 52.4 kW is necessary when the film forming speed is 2.5 nm / s. It means that.

Non-Patent Document 2 shows the results of research on power consumption in plasma generation using parallel plate electrodes.
That is, an N2 plasma generation experiment was conducted by applying 13.56 MHz power to a parallel plate electrode (size: diameter 15 cm, electrode interval: 5 cm) installed in a vacuum vessel having a diameter of 30 cm through an impedance matching device. It is shown that the amount of power consumed is measured.
As a result of the measurement, about 52% of the power output (300W) is consumed between the parallel plate electrodes, and the remaining 48% is consumed elsewhere (impedance matching device 12%, transmission circuit 24%, electrode and vacuum vessel It is shown that the ineffective plasma generation between the inner walls is 12%).
The above means that in an RF plasma CVD apparatus using parallel plate electrodes, about 52% of the electric power supplied from the power source is consumed between the target electrodes.

Non-Patent Document 3 shows the results of research on the development of a plasma CVD apparatus using a large-area, uniform VHF plasma generation method using a ladder-type electrode described in Patent Document 2 described later.
That is, Non-Patent Document 3 shows an outline of a plasma CVD apparatus used for research and a film forming experiment. As an apparatus used in the experiment, there is shown a plasma CVD apparatus having a structure in which a substrate heater, a ladder electrode, and a back plate are disposed facing each other in a vacuum vessel. The VHF power supply to the ladder-type electrode (two vertical bars of the same length installed in one plane and connected between them by a plurality of horizontal bars of the same length) is supplied to two opposing sides. This is done from the installed feeding point. At that time, the phase difference of the voltage of the power supplied to the two sides is changed with time, for example, changed into a sine wave shape and supplied. The output of the impedance matching unit is divided into eight branches using a plurality of T-type coaxial connectors and connected to eight feeding points. There are a total of 16 feeding points on both sides.
As an experimental result, the electrode dimensions are 1.2 mx 1.5 m, the substrate area is 1.1 mx 1.4 m, the power frequency is 60 MHz, the distance between the ladder electrode and the substrate heater is 20 mm, and the pressure is 45 Pa (0.338 Torr). The film formation rate of amorphous Si is 1.7 nm / s, and the non-uniformity of the film is ± 18%.

Non-Patent Document 4 shows the results of research on the development of a plasma CVD apparatus using a large-area, uniform VHF plasma generation method using a ladder-type electrode described in Patent Document 3 to be described later.
That is, Non-Patent Document 4 shows an outline of a plasma CVD apparatus used for research and a film forming experiment. As an apparatus used for the experiment, there is shown a plasma CVD apparatus having a structure in which a ladder electrode and a ground electrode are separated and installed in a vacuum container. The VHF power supply to the ladder-type electrode (two vertical bars of the same length installed in one plane and connected between them by a plurality of horizontal bars of the same length) is supplied to two opposing sides. This is done from the installed feeding point. At this time, the phase difference between the voltages of the electric power supplied to the two sides is supplied in a sine wave shape. An eight-branch power divider (Power Divider) is installed between the impedance matching device and a plurality of feeding points installed on one side.
As an experimental result, the electrode dimensions are 1.25 mx 1.55 m (rod diameter: 10 mm), the substrate area is 1.1 mx 1.4 m, the power supply frequency is 60 MHz, and the voltage phase difference is a sine wave with a frequency of 20 KHz. Under the conditions that the distance between the ladder electrode and the substrate heater is 20 mm and the pressure is 45 Pa (0.338 Torr), the amorphous Si film formation rate is 0.5 nm / s, and the non-uniformity of the film is ± 15%.

Patent Document 1 discloses an invention related to a VHF plasma CVD apparatus using a ladder-type electrode and a method therefor.
That is, the technique described in Patent Document 1 is a method for manufacturing a photoelectric conversion apparatus using a plasma CVD apparatus in which a discharge electrode and a ground electrode are disposed in a chamber so as to face each other. (B) a step of setting the distance between the substrate and the discharge electrode to 8 mm or less, (C) the substrate Is heated to 180 to 220 ° C. by a heater built in the ground electrode, (D) a material gas is supplied into the chamber, and (E) the pressure in the chamber is set to 600 Pa to 2000 Pa. (F) forming a power generation layer on the substrate by supplying ultrahigh-frequency power to the discharge electrode and converting the material gas into plasma; and (G) n on the power generation layer. Process for forming a layer A process for producing a photovoltaic device comprising a.
The technique described in Patent Document 1 is characterized in that, in the step (F), the power density of the super-high frequency power is 3.0 KW / m 2 or more.
The technique described in Patent Document 1 is characterized in that, in the step (F), the frequency of the ultrahigh frequency power is 40 MH or more.
Further, as a condition for obtaining a conversion efficiency of 12 to 12.5% at a film forming speed of 3 to 3.5 nm / s, data of a power density of 5 to 6 kW / m 2 at a pressure of 800 Pa is shown.

Patent Document 2 discloses a method of generating a large area and uniform VHF plasma.
That is, in the technique described in Patent Document 2, a substrate to be processed held by a single holding electrode and a single discharge electrode are arranged facing each other in a discharge container, and the discharge electrode and the substrate to be processed are arranged. A method of supplying power to a discharge electrode that generates a substantially uniform discharge state in a wide range between the two, wherein the power is supplied to one power supply point when power is supplied to the discharge electrode through a plurality of power supply points. The voltage distribution generated in the discharge electrode is changed by temporally changing the difference between the phase of the voltage waveform of the high frequency power and the phase of the voltage waveform of the high frequency power supplied to at least one other feeding point. Thus, the average value per unit time or the integrated value per unit time of the voltage distribution is made substantially uniform, and the occurrence of standing waves in the voltage distribution of the discharge electrode in the previous period is suppressed. .
Moreover, the technique described in Patent Document 2 is characterized in that the discharge electrode is a ladder-type electrode.
Moreover, the high frequency used is in the range of 30 to 800 MHz.

Patent Document 3 discloses an apparatus that generates a uniform plasma with a large area using a ladder-type electrode.
That is, the technique described in Patent Document 3 is a structure of a ladder-type discharge electrode for generating plasma in a plasma chemical vapor deposition apparatus, and feeds high-frequency power having a first same frequency to power supply portions at both ends of the ladder-type discharge electrode. And a cycle for feeding a high frequency of a second different frequency, and the cycle is alternately switched to feed the power, and the crossbar is perpendicular to the axial direction of the discharge electrode. In addition, the plasma generated by changing the standing wave shape is made uniform.
The technique described in Patent Document 3 is a structure of a ladder-type discharge electrode for generating plasma in a plasma chemical vapor deposition apparatus, and feeds high-frequency power having a first same frequency to power supply portions at both ends of the ladder-type discharge electrode. And a cycle for feeding a high frequency of a second different frequency, and the cycle is alternately switched to feed the power, and the crossbar is perpendicular to the axial direction of the discharge electrode. In addition, the diameter of the ladder-type discharge electrode is reduced within a range in which the standing wave wavelength is increased, and the generated plasma is made uniform.
The technique described in Patent Document 3 is a structure of a ladder-type discharge electrode for generating plasma in a plasma chemical vapor deposition apparatus, and feeds high-frequency power having a first same frequency to power supply portions at both ends of the ladder-type discharge electrode. And a cycle for feeding a high-frequency wave of a second different frequency. The cycle is alternately switched to feed power, and the discharge electrode is divided into a plurality of parts in a direction perpendicular to the axial direction. Further, the present invention is characterized in that the power balance in the left-right direction of the discharge electrode is achieved to reduce the deviation of plasma density.

Patent Document 4 discloses a method capable of generating a large VHF plasma with a large area by alternately generating two standing waves between a pair of electrodes in terms of time.
That is, the technique described in Patent Document 4 generates a plasma in which a substrate is set, a vacuum vessel provided with an exhaust system, a discharge gas supply system that supplies a discharge gas into the vacuum vessel, and plasma. A pair of electrodes composed of a first electrode and a second electrode; a first high-frequency power source capable of arbitrary pulse modulation and capable of arbitrarily setting a phase difference between two outputs and the voltage of the two outputs; The first and second impedance matching units connected to the two output terminals of one high frequency power source and arbitrary pulse modulation synchronized with the pulse modulation signal of the first high frequency power source are possible, and two outputs are provided. A power supply system comprising a second high-frequency power source capable of arbitrarily setting a phase difference between the voltages of the two outputs, and third and fourth impedance matching units connected to two output terminals of the second high-frequency power source; And use the generated plasma. Then, a plasma surface treatment method for treating a surface of a substrate, wherein a position of an antinode of a first standing wave generated between the pair of electrodes by two outputs of the first high-frequency power source and the second The distance of the antinode position of the second standing wave generated between the pair of electrodes by the two outputs of the high frequency power source is set to a quarter of the wavelength λ of the power used, that is, λ / 4. The plasma surface treatment method is characterized.
Further, the technique described in Patent Document 4 generates a plasma in which a substrate is set, a vacuum vessel provided with an exhaust system, a discharge gas supply system that supplies a discharge gas into the vacuum vessel, and plasma. A pair of electrodes composed of a first electrode and a second electrode; a first high-frequency power source capable of arbitrary pulse modulation and capable of arbitrarily setting a phase difference between two outputs and the voltage of the two outputs; The first and second impedance matching units connected to the two output terminals of one high frequency power source and arbitrary pulse modulation synchronized with the pulse modulation signal of the first high frequency power source are possible, and two outputs are provided. A power supply system comprising a second high-frequency power source capable of arbitrarily setting a phase difference between the voltages of the two outputs, and third and fourth impedance matching units connected to two output terminals of the second high-frequency power source; And use the generated plasma. A plasma surface treatment method for treating a surface of a substrate, comprising: a Si-based film having a phase difference between two outputs of the first high-frequency power source and a sinusoidal film thickness distribution formed on the substrate surface A first step for grasping the relationship with the position where the film thickness becomes maximum, a phase difference between two outputs of the second high-frequency power source, and a Si film having a sinusoidal film thickness distribution formed on the substrate surface. A second step of grasping the relationship with the position where the film thickness of the system film is maximized, and two output positions of the first and second high-frequency power sources respectively grasped in the first and second steps. A third Si film is formed on the substrate by setting the phase difference between the two outputs of the first and second high-frequency power sources based on the relationship between the phase difference and the position where the film thickness is maximized. A plasma surface treatment method comprising the steps of:
If the first standing wave and the second standing wave are generated between the pair of electrodes and the distance between the antinodes is a quarter of the wavelength λ of the power used, the pair of electrodes The power intensity I (x) between them is as follows, and is uniform (constant value) regardless of the frequency.
I (x) = cos ² (2πx / λ + Δθ / 2) + sin ² (2πx / λ + Δθ / 2)
Where x is the distance in the propagation direction of the supplied power, λ is the wavelength of the used power, and Δθ is the initial phase difference at the feeding point.

Patent Document 5 discloses an apparatus and a method related to a technique for installing a balance-unbalance conversion device between an impedance matching unit and a feeding point on an electrode in a power supply circuit.
That is, the technique described in Patent Document 5 is an impedance matching between a vacuum vessel provided with an exhaust system, a discharge gas supply system that supplies a discharge gas into the vacuum vessel, a plasma generation electrode, and a high-frequency power source. And a substrate holding means for arranging a substrate to be plasma-processed, and used for a plasma surface processing apparatus for processing the surface of the substrate using the generated plasma. A balanced transmission circuit in which two outer conductors of coaxial cables having substantially the same length are short-circuited at both ends, and each core wire at one end of the two coaxial cables is input. A balanced transmission circuit having a configuration in which each core wire at the other end is used as an output unit.
In addition, the technique described in Patent Document 5 includes impedance matching between a vacuum vessel provided with an exhaust system, a discharge gas supply system that supplies a discharge gas into the vacuum vessel, an electrode for plasma generation, and a high-frequency power source. And a substrate holding means for arranging a substrate to be plasma-processed, and used for a plasma surface processing apparatus for processing the surface of the substrate using the generated plasma. A balanced transmission circuit, in which two outer conductors of coaxial cables having substantially the same length are short-circuited by other conductors at both ends, and each of one ends of the two coaxial cables The balanced transmission circuit has a configuration in which the core wire is used as an input unit, and each core wire at the other end is used as an output unit.
The technique described in Patent Document 5 includes a vacuum vessel provided with an exhaust system, a discharge gas supply system that supplies a discharge gas into the vacuum vessel, and first and second electrodes that generate plasma. A pair of electrodes, a power supply system including a high-frequency power source, an impedance matching unit, and a balance-unbalance conversion device, and substrate holding means for arranging a substrate to be plasma-treated, and using the generated plasma, In the plasma surface treatment apparatus for treating a surface, a balanced transmission circuit having a plurality of openings is provided in the pair of electrodes, a power supply point is arranged on each peripheral edge of the pair of electrodes, and the above configuration is used. The plasma surface treatment apparatus has a configuration in which an output circuit of the balance-unbalance conversion device of the power supply system component is connected to a power supply point of the pair of electrodes.
The technique described in Patent Document 5 includes a vacuum vessel provided with an exhaust system, a discharge gas supply system that supplies a discharge gas into the vacuum vessel, and first and second electrodes that generate plasma. A pair of electrodes, a power supply point for the pair of electrodes, a power supply system including a high-frequency power source, an impedance matching device, and a balance-unbalance converter, a substrate holding means for arranging a substrate to be plasma-treated, An apparatus configuration of a power supply circuit that supplies a power from the power supply system to the pair of electrodes in a plasma surface treatment apparatus that includes a balanced transmission circuit having a configuration and processes the surface of a substrate using generated plasma. The high-frequency power supply, the impedance matching device, the balance-unbalance conversion device, the balanced transmission circuit, and the power supply point are arranged in order from the upstream side to the downstream side of the flow of power. A plasma surface treatment apparatus.
Patent Document 5 discloses that a conventional plasma CVD apparatus using a parallel plate electrode and a plasma CVD apparatus using a ladder-type electrode generate a leakage current in a power feeding portion to the electrode used in the apparatus. It has been pointed out that abnormal discharge or arcing occurs, and that plasma is generated at a place other than the pair of electrodes, making uniform film formation difficult.
That is, in the conventional plasma CVD apparatus, the connection portion between the coaxial cable for supplying power and the electrode has a shape in which lines having different structures are connected to each other, and a leakage current is generated at the connection portion. The coaxial cable is a transmission system in which the inner conductor (core wire) and the inner surface of the outer conductor are the forward path and the return path, respectively, and the pair of electrodes has a structure corresponding to two parallel lines.
The concept of the leakage current shown here is as shown in FIG. In the figure, the current I flowing from the core wire of the coaxial cable 108 to the pair of electrodes 107a and 107b flows back between the current I1 flowing back between the pair of electrodes and the other without flowing between the pair of electrodes. Divided into current I2. The current I2 is a leakage current. Note that the current shown in FIG. 12 conceptually shows a certain moment and is an AC phenomenon, so naturally the magnitude and direction of the current shown change with time.
Further, in order to prevent abnormal discharge or arcing due to the leakage current, an apparatus combining a balanced / unbalanced converting apparatus 201 and a balanced transmission circuit composed of two coaxial cables 205a and 205b shown in FIG. 13 is used. It has been shown that In FIG. 13, the core wire and the outer conductor at the end of the power transmission coaxial cable 200 are connected to the input terminals 202 a and 202 b of the balance-unbalance conversion apparatus 201, and the output terminals 203 a and 203 b include two coaxial cables 205 a, 205b is connected to the core wire of the input part of the balanced transmission circuit. The outer conductors at both ends of the two coaxial cables 205a and 205b are short-circuited. The core wire of the output part of the balanced transmission circuit is connected to the addition 207.
In the balanced transmission circuit, since the outer conductors of the two coaxial cables 205a and 205b are short-circuited to form a closed loop, there is no leakage of current. As a result, the output current I of the balance-unbalance conversion device 201 can be supplied to the addition 207 without leaking.

Patent Document 6 discloses an apparatus and a method related to a technique for installing a balance-unbalance conversion device between an impedance matching unit and a feeding point on an electrode in a power supply circuit.
In Patent Document 6, in a surface treatment apparatus that processes the surface of a substrate disposed in a vacuum vessel using plasma, a pair of electrodes opposed to each other in the vacuum vessel and power to the pair of electrodes are respectively supplied. A coaxial cable to be supplied, a power supply point that is installed on each of the pair of electrodes and connected to a core wire of the coaxial cable, and power is supplied from the coaxial cable, and power is supplied to one electrode of the pair of electrodes. It has other conductors connecting the outer conductor of the coaxial cable to be supplied and the outer conductor of the coaxial cable that supplies power to the other electrode in the vicinity of the respective feeding points, and is supplied to the pair of electrodes. Further, there is described a surface treatment apparatus characterized in that the phase difference of the voltage of the electric power is 180 °.
Further, Patent Document 6 discloses a pair of electrodes opposed to each other in a vacuum vessel, a coaxial cable that supplies power to each of the pair of electrodes, and a core wire of the coaxial cable that is installed on each of the pair of electrodes. Are connected, a feeding point to which power is supplied from the coaxial cable, an outer conductor of the coaxial cable that supplies power to one electrode of the pair of electrodes, and the coaxial cable that supplies power to the other electrode Using a surface treatment apparatus provided with other conductors for connecting the outer conductors of each of the outer conductors in the vicinity of each of the feeding points, the substrate is disposed between the pair of electrodes, and the surface of the substrate is removed using plasma. In the surface treatment method to be processed, the method includes the steps of exhausting the inside of the vacuum vessel, supplying the discharge gas into the vacuum vessel, and supplying power to both the pair of electrodes, Serial describes a surface treatment wherein the phase difference between the voltage of the pair of the power supplied to the electrode is 180 °.

JP-A-2006-216911 (FIGS. 6, 9, 10) Japanese Patent No. 3316490 (FIGS. 1-3, 6, 7) Japanese Patent No. 3611309 (FIGS. 1, 2, 3, 4) JP-A-2005-123203 (FIGS. 1-4, 8, 9) Japanese Patent No. 3590955 (Figs. 1-8 and 15-17) Japanese Patent No. 3810748 (Fig. 1-5)

M.M. Kondo, M .; Fukawa, L .; Guo, A.A. Matsuda: High rate growth of microcrystalline silicon at low temperatures, Journal of Non-Crystalline Solids 266-269 (2000), 84-89. J. et al. A. Baggerman, R.A. J. et al. Visser, and E.M. J. et al. H. Collart: Power distribution measurements in a low-pressure N2 radio-frequency discharge, J. Biol. Appl. Phys. Vol. 76, no. 2, 15 July 1994, 738-746. H. Takatsuka, Y. et al. Yamauchi, K .; Kawamura, H .; Masima, Y. et al. Takeuchi: World's large amorphous silicon photovoltaic module, Thin Solid Films 506-507 (2006), 13-16. K. Kawamura, H .; Masima, Y. et al. Takeuchi, A .; Takano, M .; Noda, Y. et al. Yonekura, H .; Takatoka: Development of large-area a-S: H films deposition using controlled VHF plasma, Thin Solid Films 506-507 (2006), 22-26.

In addition to the problems pointed out in Non-Patent Documents 1 to 4 and Patent Documents 1 to 6, the present inventor as a problem related to the plasma CVD apparatus used for manufacturing the integrated tandem-type thin film solar cell. We found that there are the following problems peculiar in the field of manufacturing tandem-type thin film solar cells.
That is, in the manufacturing field of the integrated tandem-type thin film solar cell, there is a demand for a plasma CVD apparatus and method that can satisfy the following items (ii) to (v). However, no device and technology have been established for this.
The creation of plasma CVD apparatuses and methods related to the following (b) to (v) is important for the production of integrated tandem thin-film solar cells in order to achieve production with good reproducibility, production with high yield, and reduction in production costs. It is a problem.
The matters required in the field of manufacturing the integrated tandem thin film solar cell are as follows.
(Ii) High-speed film formation is possible and a high-quality crystalline i-layer film can be formed. For example, the film forming speed is 2 nm / s or more, and the manufactured film has good Raman spectral characteristics.
(B) A high-quality i-layer film with good uniformity can be formed at high speed on a large-area substrate having a substrate area of about 1 mx 1 m or more. For example, the substrate area is 1.1 mx 1.4 m, the film forming speed is 2 nm / s or more, and the film thickness non-uniformity is ± 10% or less (if the non-uniformity is about ± 10% or more, the integrated tandem thin film solar In the laser processing step in the battery manufacturing process, it is difficult to ensure the accuracy of film processing by laser, and it is difficult to ensure the battery performance and the yield).
(A) Abnormal discharge (arcing) does not occur in the vicinity of the power feeding section.
(Ii) Supply power is effectively used to form a high-quality crystalline i-layer film, that is, plasma is generated only between the ground electrode and the non-ground electrode on which the substrate is installed, and between the pair of electrodes Otherwise, no plasma is generated.
(E) Less power is consumed in the transmission line supplying the supplied power.
In addition, when the power loss due to the abnormal discharge (arcing) and plasma generation other than between the pair of electrodes and the power loss in the power transmission line are large, the running cost in the production line of the integrated tandem thin film solar cell is It increases and it becomes difficult to reduce the product manufacturing cost.

  Hereinafter, problems and the like in a plasma CVD apparatus using a plate type electrode and a plasma CVD apparatus using a ladder type electrode, which are conventional typical plasma CVD apparatuses, will be described.

First, an outline of the structure and technology of a plasma CVD apparatus using parallel plate electrodes, which is a typical plasma CVD apparatus in the field of thin film silicon solar cells, is described in Non-Patent Documents 1 and 2, for example. Is.
In this apparatus, a non-grounded plate-type electrode and a grounded plate-type electrode are installed facing each other, and while supplying a raw material gas therebetween, electric power is supplied to generate plasma, and the above-described ground electrode is previously formed. A silicon film is deposited on the installed substrate.
In this case, a feeding point where the core wire of the coaxial cable that supplies power to the electrode and the non-grounded electrode is connected is provided on the back surface of the non-grounded electrode. The back side surface is a surface on the back side as viewed from the plasma side generated between the non-ground electrode and the ground electrode, among the two surfaces of the non-ground electrode.
A power wave propagating as an electromagnetic wave (wave) from the feeding point is provided with a space (or an earth shield) between the non-grounded electrode and the vacuum vessel wall from one point on the back surface of the non-grounded electrode. In this case, it propagates through the space between the non-ground electrode and the earth shield and reaches between the electrodes. Then, plasma is generated between the electrodes.
In the plasma CVD apparatus using the parallel plate type electrode having the above structure, when the frequency of the power used is 10 MHz-30 MHz band and VHF band (30 MHz-300 MHz), power loss and unnecessary plasma generated other than between the electrodes are generated. In addition to the problem of generation, a standing wave that is difficult to control is generated between the electrodes, and it is difficult to generate uniform plasma. A VHF plasma CVD apparatus targeting the above has not been put into practical use.

Non-Patent Document 1 discloses that when a high quality and high speed film formation of a crystalline i-layer film for an integrated tandem thin film solar cell is performed, the input power is 2.54 W when the film formation speed is 1.7 nm / s. In the case of / cm 2 and 2.5 nm / s, it is shown to be 3.4 W / cm 2.
For example, when the substrate area is 110 cm × 140 cm (15400 cm 2), if the substrate area is simply proportionally calculated, 39.1 kW is obtained at a film forming speed of 1.7 nm / s, and 52.4 kW is obtained at 2.5 nm / s. is necessary.
Even if the power supply device of VHF has an output of about 5 to 10 kW, the purchase price of the device is as high as 80 to 100 million yen. If the output is 39.1 KW or 52.4 KW, the device is very expensive, from 400 million yen to 500 million yen.
In an actual production line, the introduction of such a very expensive apparatus greatly increases the product cost. Therefore, the plasma CVD apparatus using the parallel plate type electrode and the film forming conditions are not adopted. Have difficulty.
Further, assuming that the condition of 52.4 kW is selected for the production line of the crystalline i-layer film for the integrated tandem thin film solar cell with the substrate area of 110 cm × 140 cm and 2.5 nm / s, the following is shown. Such power consumption and power charges are required.
When the operation rate of the production line is 85%, the annual power consumption is 52.4 kW × 365 days × 24 hours / day × 0.85 = 390170.4 kWh with only one room for forming the crystalline i-layer film. . If the electricity bill is 20 yen per kWh, it will be about 7.8 million yen (even if it is 15 yen per kWh, it will be about 5.85 million yen).
In an actual production line, the enormous electricity bill as described above increases the product cost. Therefore, it is difficult to adopt the plasma CVD apparatus using the parallel plate type electrode and the film forming conditions.

According to the research results shown in Non-Patent Document 2, about 52% of the power output is consumed between the parallel plate electrodes, and the remaining 48% is consumed elsewhere (impedance matching device 12%, transmission circuit 24). %, 12% of ineffective plasma is generated between the electrode and the inner wall of the vacuum vessel.
In other words, in the application to the production of a power generation film for solar cells, about 52% is effectively consumed in the production of the power generation film, and about 48% is discarded as wasted (or harmful) power. is doing.
Considering the power consumption described in Non-Patent Document 1 in the research results of Non-Patent Document 2, annual power consumption 52.4KWx365 in only one of the film forming rooms of the crystalline i-layer film for the above production line. It means that 48% of day × 24 hours / day × 0.85 = 390170.4 kWh, that is, 187282 kWh, is discarded as wasted (or harmful) power.

As described above, the conventional plasma CVD apparatus using a parallel plate type electrode has a problem of power loss and generation of unnecessary plasma generated other than between the electrodes.
In addition, even if the specific numerical values of Non-Patent Documents 1 and 2 include an error, the existence of the power loss problem cannot be denied.

Next, in a plasma CVD apparatus using a ladder-type electrode, there are a problem that the thickness distribution of a semiconductor film to be formed is not uniform and a power loss problem as described below.
In this apparatus, for example, as described in Non-Patent Document 3, Non-Patent Document 4, Patent Document 1, Patent Document 2, and Patent Document 3, a substrate heater that also serves as a ground electrode in a vacuum vessel, The ladder electrode and the back plate installed on the back side (viewed from the substrate heater side) of the ladder electrode are spaced apart from each other. A ladder-type electrode is a structure in which two vertical bars having the same length are installed in one plane and connected between them by a plurality of horizontal bars having the same length.
The source gas may be ejected from the ladder-type electrode or from the back plate, both of which are converted into plasma by the ladder-type electrode, and a silicon-based film is formed on the substrate previously set on the substrate heater. Deposit.
The feeding point where the core wire of the coaxial cable that supplies power to the electrode and the non-grounded electrode is connected is set at the outer peripheral portion of the ladder electrode and at a point facing each other.
A power wave propagating as an electromagnetic wave (wave) from the feeding point propagates through the space between the ladder electrode and the substrate heater and the space between the ladder electrode and the back plate, and generates plasma in each of the spaces. That is, this apparatus is characterized in that plasma is generated on both sides of the ladder electrode.
In this case, the phase difference of the voltage of the power supplied from the feeding points facing each other is changed with time, for example, changed into a sine wave with a frequency of 1 KHz and supplied. As a result, in the space between the ladder electrode and the substrate heater and the space between the ladder electrode and the back plate, a standing wave that moves so as to reciprocate at a speed of, for example, 1 KHz between the feeding points facing each other. appear.
In this apparatus and method, uniform VHF plasma can be generated for a large area substrate having a substrate area of about 1 mx 1 m or more by the effect of the moving standing wave.
According to Non-Patent Document 3, the electrode dimensions are 1.2 mx 1.5 m, the substrate area is 1.1 mx 1.4 m, the power frequency is 60 MHz, the distance between the ladder electrode and the substrate heater is 20 mm, and the pressure is 45 Pa (0.338 Torr). The film formation rate of amorphous Si is 1.7 nm / s, and the non-uniformity of the film is ± 18%.
According to Non-Patent Document 4, the electrode dimensions are 1.25mx1.55m (rod diameter: 10mm), the substrate area is 1.1mx1.4m, the power frequency is 60MHz, the voltage phase difference is 20KHz sine wave, ladder electrode and substrate Under the conditions of a heater interval of 20 mm and a pressure of 45 Pa (0.338 Torr), the amorphous Si film formation rate is 0.5 nm / s, and the nonuniformity of the film is ± 15%.

Regarding the problem of the power loss and the generation of unnecessary plasma generated between the electrodes other than between the electrodes with respect to the plasma CVD apparatus using the ladder-type electrode, Non-Patent Document 3, Non-Patent Document 4, Patent Document 1, Patent Document 2, and Patent It is not described in Document 3.
However, when the structures of the devices described in Non-Patent Document 3, Non-Patent Document 4, Patent Document 1, Patent Document 2, and Patent Document 3 are viewed, power loss and other than between electrodes occur as shown below. It is easily pointed out that there is a problem of unnecessary plasma generation.
First, there is a problem of wasteful power consumption caused by the electrodes and the power feeding method. It is a double-sided discharge system that uses plasma generated on both sides of the ladder electrode, but in reality, the discharge on one side is used without setting a substrate on both sides. ing. Therefore, it can be said that the discharge on the other surface has a problem of ineffective discharge, that is, generation of unnecessary plasma. As a result, it is considered that about 30% to 40% of the total power supplied from the feeding point is wasted. That is, there is a power loss problem of wasteful plasma generation.
Note that the above-described double-sided discharge method, that is, the method of setting substrates on both sides is actually difficult to control the stable generation of double-sided plasma. It seems that the device is not so adopted.
Second, it is caused by the first problem, and has the problem of generation of powder and particles due to generation of unnecessary plasma. This problem is an important problem that causes troubles such as a reduction in the operating rate of the production line and a reduction in the performance of the power generation film to be produced.
Thirdly, when a large-area substrate having a substrate area of about 1 mx 1 m or more is targeted, a plurality of the feeding points are provided for the generation of uniform VHF plasma. A power distribution circuit used by a plurality of T-type coaxial connectors is used for a power transmission circuit that supplies power to the plurality of power supply points. For example, in Non-Patent Document 3, seven T-type coaxial connectors are used for power feeding at one end of the ladder electrode and are branched into eight branches. This branching means generates power loss at the connection between the coaxial cable and the T-type coaxial connector.
Generally, in power transmission in the VHF region, it is known that there is a power loss of 2 to 3% at the connection portion. If the loss is assumed to be 3%, the power loss due to the T-type coaxial connector is 3% × 7 × 2 (both ends) = 42%. This number is extremely large and problematic in an actual production line.
Note that Non-Patent Document 4 uses a power divider, but generally, when the number of branches increases in the power divider, the power loss within the power divider is 10-15. It can be said that it is a numerical value that is a problem.

Next, as a technique described in Patent Document 4, there is provided a first high-frequency power source of a pulse modulation system capable of arbitrarily setting the phase of the voltage of the output with two outputs, and the first high-frequency power source. Using a second high frequency power source of a pulse modulation method that is transmitted in a time zone different from the output transmission time zone, has two outputs, and can arbitrarily set the phase of the voltage of the output, A uniform plasma is generated between a pair of electrodes by generating a standing wave and a second standing wave, and setting the antinode position of the two standing waves to a quarter of the wavelength. To do.
That is, if the wavelength of the power used is λ, the propagation direction of the power is x, and the phase difference is Δθ, the strength of the first standing wave and the second standing wave generated on the pair of electrodes. Is
First standing wave = cos ² {2πx / λ + Δθ / 2}
First standing wave = sin ² {2πx / λ + Δθ / 2}
First standing wave + second standing wave = cos ² {2πx / λ + Δθ / 2} + sin ² {2πx / λ + Δθ / 2} = 1
In general, the strength of power and the strength of plasma are proportional.
The plasma intensity I (x) is expressed as follows.
I (x) = cos ² {2πx / λ + Δθ / 2} + sin ² {2πx / λ + Δθ / 2}
= 1 (means that uniform plasma generation is possible without depending on the wavelength λ of the power used)
However, among the conditions to be satisfied by the high frequency plasma CVD apparatus and method required in the field of manufacturing the above integrated tandem thin film solar cell, (ii) the power supply is effectively used for forming a high quality crystalline i layer film. That is, plasma is generated only between the ground electrode and the non-ground electrode on which the substrate is installed, and no harmful plasma is generated except between the pair of electrodes. It is not described that abnormal discharge (arcing) does not occur in the vicinity and that (e) less power is consumed in the transmission circuit that supplies the supplied power.
That is, it can be said that the technique described in Patent Document 4 has a problem of power loss due to leakage current generated at the connection portion between the end portion of the coaxial cable and the feeding point.

Next, as a technique described in Patent Document 5, a balanced / unbalanced conversion device is installed between an impedance matching device and a feeding point on an electrode in a power supply circuit, and the balanced / unbalanced conversion device and a pair of electrodes are connected. The feeding points of the two coaxial cable outer conductors that are approximately equal in length are short-circuited at least at both ends, and each core wire at one end of the two coaxial cables is used as an input unit, Since each core wire at the other end is used as the output unit, it is possible to suppress leakage current, abnormal discharge, and the like in the power feeding unit, which are problems in the prior art. As a result, the power loss problem can be effectively solved.
In addition, it is described that it is effective for uniformizing large-area plasma because abnormal discharge or the like in the power feeding unit can be suppressed.
However, with only the technique described in Patent Document 5, it is practically difficult to apply a large plasma area and uniform plasma. As a result, it is limited to application as a device that suppresses abnormal discharge or the like in the power feeding unit.
That is, among the conditions to be satisfied by the high-frequency plasma CVD apparatus and method required in the manufacturing field of the integrated tandem thin-film solar cell, (ro) high-speed, uniform on a large-area substrate having a substrate area of about 1 mx 1 m It can be said that there is a problem regarding the possibility of forming a good high-quality i-layer film.
In addition, the balanced transmission circuit described in Patent Document 5 has two coaxial cables constituting it connected by a connection terminal (current introduction terminal) installed on the wall of the vacuum vessel. There is a problem that loss occurs.
In Patent Document 5, there is no description about the power loss problem related to the connection between the coaxial cable arranged on the atmosphere side and the coaxial cable arranged on the vacuum side.

In the technique described in Patent Document 6, since the power having a voltage phase difference of 180 ° is supplied to the first and second power supply points arranged on each of the pair of electrodes, Similarly to the case, it is possible to suppress the leakage current, abnormal discharge, and the like in the power feeding unit, which are problems in the prior art. As a result, the power loss problem can be effectively solved.
However, with only the technique described in Patent Document 6, it is practically difficult to apply a large area and uniform plasma. As a result, it is limited to application as a device that suppresses abnormal discharge or the like in the power feeding unit.
That is, among the conditions to be satisfied by the high-frequency plasma CVD apparatus and method required in the manufacturing field of the integrated tandem thin-film solar cell, (ro) high-speed, uniform on a large-area substrate having a substrate area of about 1 mx 1 m It can be said that there is a problem regarding the possibility of forming a good high-quality i-layer film.
In addition, since the two coaxial cables constituting the power transmission device in the balanced transmission mode described in Patent Document 6 are connected by connection terminals (current introduction terminals) installed on the wall of the vacuum vessel, the connection terminals There is a problem that power loss occurs.
In Patent Document 6, there is no description about the power loss problem related to the connection between the coaxial cable disposed on the atmosphere side and the coaxial cable disposed on the vacuum side.

As described above, in the prior art, it is extremely difficult and impossible to satisfy all the above items (ii) to (v).
In other words, the specific technical problems of the conventional high-frequency plasma CVD technology field are, firstly, the generation of plasma only between a pair of electrodes while suppressing the occurrence of abnormal discharge, and having a large area and uniformization The second is the creation of technology that can suppress power loss in the power transmission line.

  Therefore, the present invention enables high-speed, large-area, and uniform plasma surface treatment, suppresses the occurrence of abnormal discharge and the loss of power to be supplied, and applies plasma only between a pair of electrodes. An object of the present invention is to create an idea of a technology that can be generated, and to provide a high-frequency plasma CVD apparatus and a plasma CVD method for realizing the idea.

Hereinafter, means for solving the problem will be described using the numbers and symbols used in the best mode for carrying out the present invention. These numbers and symbols are added with parentheses in order to clarify the correspondence between the description of the scope of claims and the best mode for carrying out the invention.
However, these numbers and symbols should not be used for interpreting the technical scope of the invention described in the claims.

  The current introduction terminal according to the first aspect of the present invention includes a vacuum vessel (1) provided with an exhaust system, and a discharge gas supply system (6, 7, 8, 9) for supplying a discharge gas into the vacuum vessel. A pair of electrodes (2, 3) including first and second electrodes for generating plasma, a high-frequency power source (25), an impedance matching unit (31), a balance-unbalance conversion device (33), and a current introduction terminal A plasma surface treatment apparatus comprising a power supply system comprising (40) and a substrate holding means (3) for arranging a substrate (11) to be plasma-treated, and treating the surface of the substrate using the generated plasma. The current introduction terminal (40) to be used has two tubular conductors (60) that penetrate the wall of the vacuum vessel and are installed on the wall of the vacuum vessel, and are insulated from each other by a dielectric (63). Rectangular plate conductor, ie first rectangular plate conductor (61) and a second rectangular plate-shaped conductor (62), and the first rectangular plate-shaped conductor and the second rectangular plate-shaped conductor are installed inside the tubular conductor via a dielectric (64). And one end in the length direction of the first rectangular plate conductor and the second rectangular plate conductor is disposed inside the vacuum vessel, that is, on the vacuum side, and the other end is placed in the vacuum vessel. And the other end of the tubular conductor (65) and a conductor ground shield box (66, 68) surrounding the balance-unbalance converter are brought into close contact with each other. The first and second rectangular plate conductors have an air-side end portion as an input portion, and the first and second rectangular plate conductors have a vacuum-side end portion as an output portion. To do.

  A current introduction terminal according to a second aspect of the present invention includes a vacuum vessel (1) provided with an exhaust system, and a discharge gas supply system (6, 7, 8, 9) for supplying a discharge gas into the vacuum vessel. And a pair of electrodes (2, 3) composed of first and second electrodes for generating plasma, and the first and second standing waves that are independent of each other are superimposed on the pair of electrodes. The distance between the antinode of the first standing wave and the antinode of the second standing wave is 0.22 to 0.22 of the wavelength λ of the electromagnetic wave propagating through the generated plasma between the pair of electrodes. A high frequency power source (25a, 25b, 24, 28a, 28b, 29a, 29b), an impedance matching device (31a, 31b), and a balun device (33a) set to 0.28 times, that is, 0.22 to 0.28λ. 33b) and a current introduction terminal (40), and all plasma processing. In the current introduction terminal (40) used in the plasma surface treatment apparatus for treating the surface of the substrate by using the generated plasma, the substrate holding means (3) for disposing the substrate (11) is used. Two rectangular plate-like conductors having a tubular conductor (60) installed on the wall of the vacuum vessel and penetrating the walls of the vacuum vessel and insulated from each other by a dielectric (63), that is, a first rectangular plate-like shape It has a conductor (61) and a second rectangular plate conductor (62), and the first rectangular plate conductor and the second rectangular plate conductor are placed inside the tubular conductor via a dielectric (64). One end in the length direction of the first rectangular plate conductor and the second rectangular plate conductor is placed inside the vacuum vessel, that is, on the vacuum side, and the other end is vacuumed It is arranged outside the container, that is, on the atmosphere side, and has one end (65) of the tubular conductor. A ground shield box (66, 68) made of a conductor surrounding the balance-unbalance conversion device is brought into close contact with each other, and the ends on the atmosphere side of the first and second rectangular plate conductors are used as input parts. The second rectangular plate-shaped conductor has a configuration in which an end portion on the vacuum side is an output portion.

  A current introduction terminal according to a third aspect of the present invention is the current introduction terminal of the first or second aspect, wherein the dielectric constant of the dielectric (63) between the first and second rectangular plate conductors is A current introduction terminal characterized by being 3 or more.

  A current introduction terminal according to a fourth aspect of the present invention is the current introduction terminal according to any one of the first to third aspects, wherein the first rectangular plate conductor (61) constituting the current introduction terminal (40) is provided. ) And the second rectangular plate conductor (62) are ungrounded.

  A current introduction terminal according to a fifth aspect of the present invention is the current introduction terminal according to any one of the first to fourth aspects, wherein the first rectangular plate conductor (61) and the second rectangular plate conductor ( 62) is characterized in that the dielectric (63) interposed between them has a wedge shape.

  A current introduction terminal according to a sixth aspect of the present invention is the current introduction terminal according to any one of the first to fourth aspects, wherein the characteristic impedance of the current introduction terminal (40) is from the input section to the output section. It is characterized in that the structure has a gradient type distribution that continuously decreases along.

  A balanced transmission method according to a seventh aspect of the present invention is a vacuum vessel (1) having an exhaust system, and a discharge gas supply system (6, 7, 8, 9) for supplying a discharge gas into the vacuum vessel. A pair of electrodes (2, 3) including first and second electrodes for generating plasma, a high-frequency power source (25), an impedance matching unit (31), a balance-unbalance conversion device (33), and a current introduction terminal A plasma surface treatment apparatus comprising a power supply system comprising (40) and a substrate holding means (3) for arranging a substrate (11) to be plasma-treated, and treating the surface of the substrate using the generated plasma. In the balanced transmission method used, the areas of the opposed surfaces of the pair of electrodes (2, 3) are substantially equal, and the pair of electrodes are installed in an ungrounded state, and the balanced / unbalanced conversion device (33) Output circuit and the pair of electrodes (2, 3 Are connected to the current supply terminal (40) of any of the first to sixth inventions, and the output of the balance-unbalance conversion device (33) is connected to the power supply point (20, 21). It is transmitted to the point (20, 21).

  According to an eighth aspect of the present invention, there is provided a plasma surface treatment apparatus comprising: a vacuum vessel (1) having an exhaust system; and a discharge gas supply system (6, 7, 8, 9) for supplying a discharge gas into the vacuum vessel. ), A pair of electrodes (2, 3) composed of first and second electrodes for generating plasma, a high-frequency power source (25), an impedance matching unit (31), a balance-unbalance conversion device (33), and current introduction A plasma surface treatment apparatus comprising a power supply system comprising a terminal (40) and a substrate holding means (3) for arranging a substrate (11) to be plasma treated, and treating the surface of the substrate using the generated plasma And the pair of electrodes (2, 3) have substantially equal areas, and the pair of electrodes are installed in a non-grounded state, and the balance-unbalance conversion device ( 33) output circuit and the pair of electrodes Power supply point (20, 21) is characterized by having a configuration that is connected in the first to sixth one of the current introducing terminals of the invention of (40).

  The plasma surface treatment apparatus according to the ninth aspect of the present invention comprises a vacuum vessel (1) having an exhaust system and a discharge gas supply system (6, 7, 8, 9) for supplying a discharge gas into the vacuum vessel. And a pair of electrodes (2, 3) composed of first and second electrodes for generating plasma, and the first and second standing waves that are independent of each other are superimposed on the pair of electrodes. The distance between the antinode of the first standing wave and the antinode of the second standing wave is 0.22 to 0.22 of the wavelength λ of the electromagnetic wave propagating through the generated plasma between the pair of electrodes. A high frequency power source (25a, 25b, 24, 28a, 28b, 29a, 29b), an impedance matching device (31a, 31b), and a balun device (33a) set to 0.28 times, that is, 0.22 to 0.28λ. 33b) and a current introduction terminal (40), and a plasma treatment A substrate holding means (3) for disposing a substrate (11) to be processed, and a plasma surface treatment apparatus for treating the surface of the substrate using the generated plasma, wherein the pair of electrodes (2, 3) The areas of the surfaces facing each other are substantially equal, and the pair of electrodes are installed in an ungrounded state, and the output circuit of the balance-unbalance conversion device (33a, 33b) of the component of the power supply system and the pair of electrodes The power supply points (20a, 20b, 21a, 21b) are connected by the current introduction terminal (40) of any one of the first to sixth inventions.

  A plasma surface treatment apparatus according to a tenth aspect of the present invention comprises a vacuum vessel (1) having an exhaust system, and a discharge gas supply system (6, 7, 8, 9) for supplying a discharge gas into the vacuum vessel. ), A pair of electrodes (2, 3) including first and second electrodes for generating plasma, a power supply point (20, 21) of the pair of electrodes, a high frequency power source (25), and impedance matching A substrate on which a device (31), a balance-unbalance conversion device (33), a power supply system comprising the current introduction terminal of any of the first to sixth inventions, and a substrate (11) to be plasma-processed are arranged A plasma surface treatment apparatus comprising a holding means (3) and treating the surface of the substrate using the generated plasma, wherein the power supply circuit for supplying power from the power supply system to the pair of electrodes is configured as follows: , From upstream to downstream of power flow The high-frequency power source (25), the impedance matching unit (31), the balance-unbalance conversion device (33), the current introduction terminal (40), and the power supply points (20, 21) are arranged in this order. And

  A plasma surface treatment apparatus according to an eleventh aspect of the present invention is a vacuum vessel (1) having an exhaust system, and a discharge gas supply system (6, 7, 8, 9) for supplying a discharge gas into the vacuum vessel. ), A pair of electrodes (2, 3) composed of first and second electrodes for generating plasma, and first and second standing waves that are independent of each other are superimposed on the pair of electrodes. The distance between the antinode of the first standing wave and the antinode of the second standing wave is 0.22 of the wavelength λ of the electromagnetic wave propagating through the generated plasma between the pair of electrodes. A high frequency power source (25a, 25b, 24, 28a, 28b, 29a, 29b), an impedance matching device (31a, 31b), and a balance-unbalance conversion device (set to .about.0.28 times, that is, 0.22 to 0.28λ. 33a, 33b) and the current introduction terminal of any one of the first to sixth inventions A plasma surface treatment apparatus that treats the surface of a substrate using generated plasma, the power supply system comprising: a power supply system comprising: The apparatus configuration of the power supply circuit for supplying power to the electrodes is the order of the high-frequency power source, impedance matching unit, balance-unbalance conversion device, current introduction terminal, and power supply point from the upstream side to the downstream side of the power flow. It is made to arrange in.

  A plasma surface treatment apparatus according to a twelfth aspect of the present invention is the plasma surface treatment apparatus according to any one of the eighth to eleventh aspects, wherein the current introduction terminal (40) according to any one of the first to sixth aspects. And the power supply points (20, 21) are connected by flat conductors (70, 71).

  A plasma surface treatment method according to a thirteenth aspect of the present invention comprises a vacuum vessel (1) provided with an exhaust system, and a discharge gas supply system (6, 7, 8, 9) for supplying a discharge gas into the vacuum vessel. ), A pair of electrodes (2, 3) composed of first and second electrodes for generating plasma, power supply points (20, 21) of the pair of electrodes, a high frequency power source (25), and an impedance matching device (31), a balance-unbalance conversion device (33), a power supply system comprising the current introduction terminal (40) of any one of the first to sixth inventions, and a substrate on which a substrate (11) to be plasma-processed is disposed. And a holding means (3) for processing the surface of the substrate using the generated plasma. The apparatus constituting the power supply system is arranged from the upstream side to the downstream side of the power flow. The high frequency power source (25) -Impedance matcher (31), the balanced-unbalanced converter (33), and performing the plasma surface treatment by placing the order of the current introduction terminal (40) and power supply point (20, 21).

  A plasma surface treatment method according to a fourteenth aspect of the present invention comprises a vacuum vessel (1) having an exhaust system, and a discharge gas supply system (6, 7, 8, 9) for supplying a discharge gas into the vacuum vessel. ), A pair of electrodes (2, 3) including first and second electrodes for generating plasma, a high-frequency power source (25), an impedance matching unit (31), a balance-unbalance conversion device (33), and the first A power supply system comprising the current introduction terminal according to any one of the first to sixth aspects of the present invention and a substrate holding means (3) for disposing a substrate (11) to be plasma-treated, and using the generated plasma, the substrate In the plasma surface treatment method for treating the surfaces of the pair of electrodes (2, 3), the opposing surfaces of the pair of electrodes (2, 3) are substantially equal, and the pair of electrodes are installed in an ungrounded state, and the balance-unbalance conversion is performed. The output of the device (33) is the current Is transmitted to the power supply point of installation to the electrodes through the input terminals (40) (20, 21), characterized in that the plasma surface treatment is performed.

  According to a fifteenth aspect of the plasma surface treatment method of the present application, a vacuum vessel (1) having an exhaust system and a discharge gas supply system (6, 7, 8, 9) for supplying a discharge gas into the vacuum vessel. ), A pair of electrodes (2, 3) composed of first and second electrodes for generating plasma, power supply points (20, 21) of the pair of electrodes, and the pair of electrodes independent of each other The first and second standing waves are superimposed on each other, and the distance between the antinode position of the first standing wave and the antinode position of the second standing wave is set between the pair of electrodes. A high frequency power source (25a, 25b, 24, 28a, 28b, 29a, 29b) set to 0.22 to 0.28 times the wavelength λ of the electromagnetic wave propagating through the generated plasma; Impedance matching devices (31a, 31b), balance-unbalance conversion devices (33a, 33b), and the first A power supply system comprising the current introduction terminal according to any one of the first to sixth aspects of the present invention and a substrate holding means (3) for disposing a substrate (11) to be plasma-treated, and using the generated plasma, the substrate In the plasma surface treatment method for treating the surface of the power supply, the high-frequency power supplies (25a, 25b, 24, 28a, 28b, 29a, 29b), impedance matching devices (31a, 31b), balance-unbalance conversion devices (33a, 33b), current introduction terminals (40), and power supply points (20a, 20b, 21a, 21b) are arranged in this order. A surface treatment is performed.

  According to a sixteenth aspect of the present invention, there is provided a plasma surface treatment method comprising: a vacuum vessel (1) having an exhaust system; and a discharge gas supply system (6, 7, 8, 9) for supplying a discharge gas into the vacuum vessel. ), A pair of electrodes (2, 3) composed of first and second electrodes for generating plasma, and first and second standing waves that are independent of each other are superimposed on the pair of electrodes. The distance between the antinode of the first standing wave and the antinode of the second standing wave is 0.22 of the wavelength λ of the electromagnetic wave propagating through the generated plasma between the pair of electrodes. A high frequency power source (25a, 25b, 24, 28a, 28b, 29a, 29b), an impedance matching device (31a, 31b), and a balance-unbalance conversion device (set to .about.0.28 times, that is, 0.22 to 0.28λ. 33a, 33b) and the current introduction terminal of any one of the first to sixth inventions In the plasma surface treatment method for treating a surface of a substrate using the generated plasma, a power supply system comprising: a substrate holding means (3) for disposing a substrate (11) to be plasma treated; The areas of the electrodes (2, 3) facing each other are substantially equal, and the pair of electrodes are installed in an ungrounded state, and the output of the balance-unbalance conversion device (33a, 33b) is the current introduction terminal. It is transmitted to the power supply points (20a, 20b, 21a, 21b) installed on the electrodes via (40), and plasma surface treatment is performed.

  A plasma surface treatment method according to a seventeenth aspect of the present invention is the plasma surface treatment method according to any one of the thirteenth to sixteenth aspects, wherein the two outputs of the balance-unbalance conversion device (33, 33a, 33b) The voltage phase difference is set to 180 °.

According to the present invention, it is possible to supply electric power having a voltage phase difference of 180 ° to the feeding point of the pair of electrodes, that is, electric power having the same amplitude of the forward and return currents and a phase difference of 180 °. Therefore, in the plasma generation by the pair of electrodes, the abnormal discharge in the vicinity of the feeding point is suppressed almost completely.
That is, according to the present invention, the phase difference of the voltage of the power is connected to the connection between the power supply point that is the power supply point to the electrode installed on the vacuum side and the balance-unbalance conversion device installed on the atmosphere side. Since it is possible to use a current introduction terminal that transmits power having a phase difference of 180 ° while maintaining its phase difference, abnormal discharge (arcing) does not occur in the vicinity of the power feeding point, and a pair of Plasma is generated only between the electrodes, and plasma generation other than between the pair of electrodes can be suppressed.
Further, according to the present invention, two standing waves whose antinode positions are between 0.22 and 0.28 times the wavelength λ of the electromagnetic wave propagating through the generated plasma between the pair of electrodes are generated according to the present invention. In a method that can generate and generate uniform plasma, the connection between the power supply point that is the power supply point to the electrode installed on the vacuum side and the balance-unbalance conversion device installed on the atmosphere side, Since it is possible to use a current introduction terminal that transmits power with a phase difference of 180 ° in the voltage while maintaining the phase difference, abnormal discharge (arcing) occurs near the power supply point In addition, plasma is generated only between the pair of electrodes, and plasma generation outside the pair of electrodes can be suppressed.
As a result, generation of abnormal discharge (arcing) in the vicinity of the feeding point, which is very difficult with the conventional technology, suppression of plasma generation other than between the pair of electrodes, and generation of uniform VHF plasma over a large area are achieved. Easily possible.
This means that VHF plasma capable of processing a high-quality film at high speed can be applied to a field targeting a large area substrate.
Accordingly, the present invention can be used for production lines in fields such as the manufacture of integrated tandem thin film solar cell modules and the manufacture of various devices using microcrystalline silicon films, thereby improving productivity and yield. The performance improvement effect is remarkably large. Moreover, the effect of reducing the manufacturing cost is remarkably large. Furthermore, it is expected that the manufacturing cost can be reduced by minimizing the use of electric power.

  In other words, the specific technical problems of the conventional high-frequency plasma CVD technology field are, firstly, the generation of plasma only between a pair of electrodes while suppressing the occurrence of abnormal discharge, and having a large area and uniformization The second is the creation of a technology that can be used, and the second is the creation of a technology that can suppress power loss in the power transmission line. The present invention can solve the first problem, and the second problem also. A solution can be expected. This indicates that the effect of the present invention is remarkably great.

Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the drawings. In each figure, the same code | symbol is attached | subjected to the same member and the overlapping description is abbreviate | omitted.
In the following description, an apparatus and a method for manufacturing an amorphous silicon semiconductor layer for a solar cell are described as an example of a plasma CVD apparatus and a plasma CVD method, but the subject matter of the present invention is limited to the following examples. It is not something.

Example 1
A current introduction terminal, a plasma surface treatment apparatus (plasma CVD apparatus) and a plasma surface treatment method (plasma CVD method) having the current introduction terminal according to the first embodiment of the present invention will be described with reference to FIGS. I will explain.

  FIG. 1 is a schematic view showing the entire plasma surface processing apparatus (plasma CVD apparatus) having a current introduction terminal according to the first embodiment of the present invention, and FIG. 2 is a current introduction according to the first embodiment of the present invention. FIG. 3 is a schematic diagram showing the entire terminal, FIG. 3 is an explanatory diagram relating to a connection portion between a balance-unbalance converter, a current introduction terminal, and an electrode in the power supply system of the plasma surface treatment apparatus shown in FIG. 1, and FIG. It is explanatory drawing regarding the characteristic impedance of the current introduction terminal concerning the 1st Embodiment of this invention.

First, the configuration of a plasma surface treatment apparatus (plasma CVD apparatus) provided with a current introduction terminal according to the first embodiment of the present invention will be described.
1 to 3, reference numeral 1 denotes a vacuum vessel. The vacuum vessel 1 is provided with a pair of electrodes for converting a discharge gas, which will be described later, into plasma, that is, a first non-ground electrode 2 and a second non-ground electrode 3, and a substrate heater 4.
The first non-grounded electrode 2 is installed in the vacuum vessel 1 via insulator supports 5a and 5b and a discharge gas mixing box 6 described later. The second non-grounded electrode 3 is installed on the substrate heater 4 via insulator support members 5c and 5d.
The first and second non-grounded electrodes 2 and 3 are installed with the areas of the opposing surfaces being substantially equal.
The discharge gas mixing box 6 is used in combination with the rectifying plate 7, the gas supply pipe 8 and the first non-grounded electrode 2, and discharge gas is uniformly distributed between the first and second non-grounded electrodes from the gas ejection hole 9. To erupt. In addition, the diameter of the gas ejection hole 9 is about 0.2-0.8 mm, for example, 0.6 mm.
Reference numerals 10a and 10b are exhaust pipes, and the gas in the vacuum vessel 1 is discharged by a vacuum pump (not shown).
Reference numeral 11 denotes a substrate to be plasma-processed. The substrate 11 is placed on the second non-grounded electrode 3 by opening and closing a gate valve (not shown). Then, the substrate heater 4 is heated to a predetermined temperature.

  The pressure in the vacuum vessel 1 is monitored by a pressure gauge (not shown), and is automatically adjusted and set to a predetermined value by a pressure adjustment valve (not shown). In this embodiment, when the discharge gas has a flow rate of about 500 sccm to 1,500 sccm, the pressure can be adjusted to about 0.01 Torr to 10 Torr (1.33 Pa to 1,330 Pa). The vacuum ultimate pressure of the vacuum vessel 1 is about 2 to 3E-7 Torr (2.66 to 3.99E-5 Pa).

Reference numeral 25 denotes a high-frequency power source, which generates power having a frequency of 30 MHz to 300 MHz (VHF band), for example, 60 MHz. The high frequency power supply 25 adjusts and outputs electric power of an arbitrary magnitude within an output range of 0.5 to 10 kW. The output is supplied to the power supply points 20 and 21 of the pair of electrodes 2 and 3 via the coaxial cable 30, the impedance matching unit 31 described later, the coaxial cable 32, the balance-unbalance conversion device 33 described later, and the current introduction terminal 40 described later. To be supplied.
Reference numeral 33 denotes a balanced / unbalanced conversion device, for example, an LC bridge type balanced / unbalanced conversion device, which converts unbalanced transmission power input to this device into balanced transmission power. Note that balanced transmission power is a form of power transmission that is transmitted through two parallel lines called rehel lines used for TV and radio antennas, etc., and the amplitudes of the forward and return currents are equal and the phase is 180 °. It is characterized by being different. Non-equilibrium transmission power is a form of power transmission that is transmitted using a coaxial cable, and a ground (vacuum container, parts built in a vacuum container, etc.) is used as a part of the transmission circuit, and the current of the forward and return paths is measured. The phase is not 180 °.
In addition, the balance-unbalance converter used in the plasma surface treatment apparatus (plasma CVD apparatus) provided with the current introduction terminal of the first embodiment related to the present invention shown in FIG. For example, a super-top type balance / unbalance conversion device, a balance / unbalance conversion device using a branch conductor, and a balance / unbalance conversion device using a transformer may be used.

Reference numeral 40 is a current introduction terminal. As shown in FIGS. 2 and 3, the current introduction terminal 40 includes a tubular conductor 60, a flange 65, a first rectangular plate-shaped conductor 61, a second rectangular plate-shaped conductor 62, and a first dielectric 63. And a second dielectric 64. Examples of the first and second dielectrics include silicon oxide SiO2 (relative dielectric constant = about 4), silicon nitride SiN4 (relative dielectric constant = about 7), and alumina Al2O3 (relative dielectric constant = 8.5 to 11). Choose from ceramics. Here, for example, alumina having a relative dielectric constant of 10 is used.
A flange 65 used for joining to the vacuum vessel 1 is fixed to one end of the tubular conductor 60. Connection terminals 61 a and 62 a used for connection to the first and second electrodes 2 and 3 are fixed to one end of the first and second rectangular plate-like conductors 61 and 62.
In FIG. 3, the balanced transmission circuit 40 is installed in the vacuum vessel 1 through the flange 65 of the tubular conductor 60 that constitutes the current introduction terminal 40. At this time, one end of the current introduction terminal 40 is installed on the atmosphere side and the other is installed on the vacuum side. Note that the airtightness is maintained between the vacuum vessel 1 and the current introduction terminal 40 by an O-ring. The tubular conductor 60 is supported on the vacuum vessel 1 by a tubular conductor support conductor 67.

In the plasma surface treatment apparatus (plasma CVD apparatus) having the current introduction terminal illustrated in FIG. When supplying the first and second electrodes 2 and 3, the balance-unbalance conversion device 33 is used to connect the first and second electrodes 2 and 3. At that time, maintaining the phase difference between the two output voltages of the balance-unbalance conversion device 33 at 180 ° and supplying it to the first and second electrodes 2 and 3 is extremely important for preventing abnormal discharge. .
Therefore, in FIG. 1 and FIG. 3, the step of confirming that the voltage phase difference between the two outputs of the balance-unbalance conversion device 33 is 180 ° using a voltage phase difference measuring device (not shown) described later is extremely is important.

Here, the characteristics of the current introduction terminal 40 as a transmission circuit will be described.
In FIG. 3, the flange 65 on the atmosphere side of the current introduction terminal 40 is connected to a ground shield box 66 of the balance-unbalance conversion device 33 described later, and the power radiated from the electric circuit components inside the balance-unbalance conversion device 33 and The power radiated from the first and second rectangular plate conductors 61 and 62 of the current introduction terminal 40 is shielded.
The earth shield box 66 is a box that surrounds the balance-unbalance conversion device 33 with a conductor, and prevents leakage of electric power generated from the balance-unbalance conversion device 33.
Further, it is extremely important to connect the flange 65 and the flange 68 of the earth shield box 66 in order to prevent the power radiation.
One of the two outputs of the balun 33 is connected to a connection point 70 at the end of the first rectangular plate-shaped conductor 61 of the input portion of the current introduction terminal 40, and the other is connected to the input portion of the current introduction terminal 40. The second rectangular plate conductor 62 is connected to the connection point 71 at the end.
An end portion 61 a of the first rectangular plate conductor at the output portion of the current introduction terminal 40 is connected to the first electrode 2. Here, the connection point between the end portion 61 a of the first rectangular plate-shaped conductor 61 and the first electrode 2 is referred to as a first power supply point 20.
The end portion 62 a of the second rectangular plate conductor 62 at the output portion of the current introduction terminal 40 is connected to the second electrode 3. Here, a connection point between the end portion 62 a of the second rectangular plate conductor and the second electrode 3 is referred to as a second power supply point 21.
With the above configuration, as shown in FIG. 3, the output power of the high-frequency power supply 25 is transmitted to the balanced / unbalanced conversion device 33 via the impedance matching device 31 and the coaxial cable which is an unbalanced transmission line, and the balanced / unbalanced conversion is performed. The power converted into the balanced transmission form by the device 33 is supplied to the power supply points 20 and 21 of the pair of electrodes 2 and 3 via the current introduction terminal 40.
In this configuration, the direction of the electric field of power propagating between the first and second rectangular plate conductors 61 and 62 constituting the current introduction terminal 40 is determined by the first and second rectangular plate conductors 61 and 62. Since it is in the normal direction of the surface, the power transmission form functions as a balanced transmission circuit. Here, the balanced transmission circuit and the balanced transmission line are used as the same meaning.
In this configuration, since the first and second rectangular plate conductors 61 and 62 are surrounded by the tubular conductor 60 and the earth shield 66, the first and second rectangular plate conductors 61 and 62 are separated from each other. There is no radiation to the atmosphere of the strong leakage electric field generated from the atmosphere.

According to the characteristics of the current introduction terminal 40, in addition to the function as the current introduction terminal, the current introduction terminal 40 is an electric circuit as a balanced transmission circuit, like two parallel lines called Rehel lines. It has the function of.
Due to this feature, in the application to the plasma surface treatment apparatus (plasma CVD apparatus) shown in FIG. 1, the amplitudes of the forward and return currents are equal and the phases are 180 ° different at the power supply points of the pair of electrodes 2 and 3. It is possible to supply power characterized by the above. As a result, plasma can be generated only between the pair of electrodes 2 and 3.

The value of the characteristic impedance of the current introduction terminal 40 depends on the width W and interval h of the first and second rectangular plate conductors 61 and 62 and the relative dielectric constant of the dielectric therebetween.
As a calculation method of the characteristic impedance value, for example, several calculation formulas have been proposed in wireless engineering or transmission circuit science. Here, the characteristic impedance Z ₀ (Ω) of the current introduction terminal 40 is evaluated by the following commonly used calculation formula.
Z ₀ (Ω) = 120π / ε ^1/2 {W / h + 1.393 + 0.667ln (W / h + 1.444)} (1)
Where Z ₀ (Ω) is the characteristic impedance of the flat plate transmission line, ε is the relative dielectric constant, W is the width of the flat plate (m), and h is the distance (m) between the two flat plates.
FIG. 4 shows the value of the characteristic impedance of the current introduction terminal 40 calculated using the formula (1) for calculating the characteristic impedance Z ₀ (Ω). However, this is the case where the relative dielectric constant ε is 3, 6.5 and 10.
Here, high-purity alumina having a relative dielectric constant ε = about 10 is used. Then, the following three current introduction terminals 40 are prepared. However, the length and width of the first and second rectangular plate conductors 61 and 62 are the same.
First current introduction terminal 40a... Length of tubular conductor 60 = 10 cm (thickness = 1.5 cm), inner diameter = 14 cm (thickness = 1.5 cm), first and second rectangular plate conductors 61, 62 length = 14 cm, width W = 5 cm (thickness 3 mm), the interval h = 2.5 cm, that is, W / h = 2, characteristic impedance Z ₀ = about 30Ω.
Second current introduction terminal 40b... Length of tubular conductor 60 = 10 cm (thickness = 1.5 cm), inner diameter = 14 cm (thickness = 1.5 cm), first and second rectangular plate conductors 61, 62 length = 14 cm, width W = 5 cm (thickness 3 mm), the interval h = 1 cm, that is, W / h = 5, characteristic impedance Z ₀ = about 15Ω.
Third current introduction terminal 40c... Length of tubular conductor 60 = 10 cm (thickness = 1.5 cm), inner diameter = 14 cm (thickness = 1.5 cm), first and second rectangular plate conductors 61, 62 length = 14 cm, width W = 5 cm (thickness 3 mm), the interval h = 0.5 cm, that is, W / h = 10, characteristic impedance Z ₀ = about 10Ω.

The relative dielectric constants of the first and second rectangular plate conductors 61 and 62 may generally be selected from arbitrary values, but if the relative dielectric constant is small, the first and second rectangular dielectric conductors 61 and 62 may be selected. As a result, the dimension of the current introduction terminal 40 is increased.
In order to design the outer dimension of the tubular conductor 60 of the current introduction terminal 40 within about 15 cm, a relative dielectric constant of 3 or more is practical.

Next, a characteristic selection test (referred to as a selection process) of the current introduction terminal 40 that is performed in advance when the amorphous Si for an a-Si solar cell is formed using the plasma surface treatment apparatus having the above configuration will be described. .
Here, specifically, one suitable for the following amorphous Si film forming conditions is selected from the three current introduction terminals 40a, 40b, and 40c.
The film formation conditions for amorphous Si are as follows.
(Film forming conditions)
● Discharge gas: SiH4,
● Flow rate: 500sccm,
● Pressure: 0.5 Torr (66.5 Pa),
● Electrode size: 70cm x 5cm,
● Electrode spacing: 2.5cm,
● Power supply frequency: 60 MHz
● Power: 800W
-Substrate temperature: 180 ° C.

From the three current introduction terminals 40, that is, the first current introduction terminal 40a, the second current introduction terminal 40b, and the third current introduction terminal 40c, a balanced transmission circuit suitable for the film formation conditions of the amorphous Si is selected. As a current introduction terminal that can match the distance between the electrodes 2 and 3 under the above-described amorphous Si film forming condition = 2.5 cm, the distance between the first and second rectangular plate conductors 61 and 62 is 2. There is only a first current introduction terminal 40a of .5 cm.
That is, the length of the first and second rectangular plate-shaped conductors 61 and 62 is 14 cm, the width W is 5 cm (thickness 3 mm), the distance h is 2.5 cm, that is, the characteristic impedance Z is W / h = 2. The first current introduction terminal 40a having the characteristic of ₀ = about 30Ω must be selected.

Next, in response to the result of the selection test of the current introduction terminal 40, the process proceeds to the film forming process.
Then, the substrate 11 is previously set on the second non-grounded electrode 3 and a vacuum pump (not shown) is operated to remove impurity gas and the like in the vacuum vessel 1. For example, while supplying at 500 sccm and a pressure of 0.5 Torr (66.5 Pa), high-frequency power, for example, power at a frequency of 60 MHz, for example, 800 W is supplied to the pair of electrodes 2 and 3. The substrate temperature is kept in the range of 80 to 350 ° C., for example, 180 ° C.

That is, in FIGS. 1 to 3, the output of the high frequency power supply 25 is set to 800 W at 60 MHz, for example, and the output is passed through the coaxial cable 30, the impedance matching unit 31, the coaxial cable 32, the balance-unbalance conversion device 33, and the current introduction terminal 40a. Then, the power is supplied to the feeding points 20 and 21 of the first and second electrodes 2 and 3.
In this case, the LC adjuster of the impedance matching unit 31 and the traveling wave and reflected wave power value monitors attached to the high-frequency power source 31 are used in combination to reflect the supplied power on the upstream side of the impedance matching unit 31. You can prevent the waves from returning.
However, when viewed from the impedance matching unit 31 side, the balance / unbalance conversion device 33 on the downstream side, the current introduction terminal 40a (characteristic impedance Z ₀ = about 30Ω), and a pair of amorphous Si film forming conditions When impedance matching with a load made of plasma generated between the electrodes 2 and 3 is not good, a certain amount of reflected wave returns. Generally, it is about 1 to 5%, that is, about 8 to 40 W with respect to the output 800 W of the high frequency power supply 31.
Further, the phase difference of the voltage of the output of the balun 33 is 180 degrees at the input portion of the current introduction terminal 40, that is, at the end of the first and second rectangular plate conductors 61 and 62 on the atmosphere side. This is monitored by a voltage measuring device (not shown).
When electric power is supplied to the feeding points 20 and 21 of the first and second electrodes 2 and 3, plasma of SiH 4 gas is generated between the pair of electrodes 2 and 3. In this plasma generation, the pair of electrodes 2 and 3 have substantially the same area and are not grounded, and the power is different from the power supply points 20 and 21 by a voltage phase difference of 180 °, that is, the forward path. Since electric power having the same return current amplitude and a phase difference of 180 ° is supplied, abnormal discharge in the vicinity of the feeding points 20 and 21 is completely suppressed. The generated plasma is only between the pair of electrodes 2 and 3.
The reason why plasma is generated except between the pair of electrodes 2 and 3 is that the power transmission circuit supplied to the electrodes is leaked due to the unbalanced transmission circuit and one of the pair of electrodes is grounded. Leakage current generated by
In addition, the main cause of abnormal discharge in the vicinity of the feeding points 20 and 21 is that the power transmission circuit supplied to the electrodes is leaked due to the unbalanced transmission circuit and one of the pair of electrodes is grounded. The leakage current generated by

That is, in the power supply from the output portion of the current introduction terminal 40, that is, the vacuum side end portions of the first and second rectangular plate conductors 61 and 62 to the power supply points 20 and 21, the pair of electrodes 2 and 3 are Since it has the same electrical characteristics as a balanced transmission line similar to the current introduction terminal 40, the occurrence of leakage current is suppressed.
As a result, no abnormal discharge or local discharge occurs. Furthermore, as described above, since the phase difference between the voltages applied to the power supply points 20 and 21 is 180 degrees, that is, since a positive and negative voltage is applied to the pair of electrodes, the electrodes 2 and 3 There is no generation of plasma outside the gap.
Therefore, there is no generation of plasma due to the leakage current related to the ground structure and wiring situation around the pair of electrodes, which is a problem in the prior art, and stable plasma generation with high reproducibility is possible.

  However, when the impedance matching device 31 is arranged downstream of the balance-unbalance conversion device 33, that is, between the balance-unbalance conversion device 33 and the balanced transmission circuit 40, the LC built-in in the impedance matching device 31 is provided. Since the circuit is adjusted for impedance matching between the load, the power source, and the transmission path, the phase difference of the voltage applied to the current introduction terminal 40 cannot be secured at 180 degrees. Therefore, it is important that the place where the impedance matching device 31 is disposed is upstream of the balance-unbalance conversion device 33.

In the above process, when SiH 4 gas is turned into plasma, 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 12, thereby depositing an a-Si film. To do.
It is a well-known technique that microcrystalline Si, thin-film polycrystalline Si, or the like can be formed by optimizing the flow ratio, pressure, and power of SiH4 and H2 in the film forming conditions.

Here, a-Si having a film forming speed of 1 nm / s and a film thickness distribution of ± 10% is formed on a glass substrate 11 having a size of about 700 mm × 50 mm (thickness 3 mm).
The film forming conditions are as follows.
(Film forming conditions)
● Discharge gas: SiH4,
● Flow rate: 500sccm,
● Pressure: 0.5 Torr (66.5 Pa),
● Electrode size: 70cm x 5cm,
● Electrode spacing: 2.5cm,
● Power supply frequency: 60 MHz
● Power: 800W
-Substrate temperature: 180 ° C.

When plasma is generated under the above-mentioned film forming conditions, the output of the high frequency power supply 25 is transmitted to the balance / unbalance conversion device 33 via the coaxial cable 30 and the impedance matching unit 31 which are unbalanced transmission circuits, and the transmitted power is balanced. Since it is converted into balanced power by the unbalanced converter 33 and can be supplied to the power supply points 20 and 21 of the pair of electrodes 2 and 3 through the current introduction terminal 40 having the characteristics of a balanced transmission circuit, the power supply system and the load Transmission characteristics at a connection portion between a certain pair of electrodes 2 and 3 are matched, and generation of leakage current is suppressed.
Therefore, the spatial distribution of the density of the generated plasma is uniform with good reproducibility compared to the conventional case. As a result, the film thickness distribution of the a-Si film to be formed becomes uniform with good reproducibility compared to the conventional case. Numerically, film formation is possible when the a-Si film thickness distribution is within ± 10%.

A balanced transmission circuit (or balanced transmission line) is a transmission form in which a current flowing through both lines is equal in amplitude and phase is 180 ° different in a power transmission circuit composed of two conductors. It is.
In addition, the LC bridge type unbalanced conversion device used in this embodiment is means for converting the power transmission of the unbalanced transmission method input to the device into the balanced transmission method. Thus, a super-top type balance-unbalance converter, a half-wavelength bypass type balance-unbalance converter, and the like can be used. Also, a device combining a power distributor and a phase shifter can be used.

In the present embodiment, since the feeding point is set to one point (a pair) for each of the pair of electrodes 2 and 3, the substrate size is limited to about 700 mm × 50 mm. However, if the number of feeding points is increased, the width of the size is increased. It is natural that it can be expanded.
In addition, if a plurality of pairs of electrodes are installed and a plurality of the above-described power supply systems are arranged according to the number of the electrodes, it is natural that the width of the substrate size can be expanded.

Further, in the manufacture of a-Si solar cells, thin film transistors, and photosensitive drums, there is no problem in performance as long as the film thickness distribution is within ± 10%. According to the above embodiment, it is possible to obtain a remarkably good film thickness distribution as compared with the conventional apparatus and method even when a power supply frequency of 60 MHz is used.
This means that the industrial value related to productivity improvement and cost reduction in the manufacturing field of a-Si solar cells, thin film transistors, and photosensitive drums is remarkably large.

(Example 2)
A current introduction terminal, a plasma surface treatment apparatus (plasma CVD apparatus) and a plasma surface treatment method (plasma CVD method) provided with the current introduction terminal according to the second embodiment of the present invention will be described with reference to FIGS. I will explain. Moreover, FIGS. 1-4 is referred as needed.

  FIG. 5 is a conceptual diagram showing a current introducing terminal and electrode connecting means according to the second embodiment of the present invention, and FIG. 6 is a first of the current introducing terminal and electrode connecting means according to the second embodiment of the present invention. FIG. 7 and FIG. 7 are explanatory views showing a second specific example of the means for connecting the current introduction terminal and the electrode according to the second embodiment of the present invention.

First, the configuration of the current introduction terminal according to the second embodiment of the present invention will be described. However, the same members as those shown in FIG. 1 to FIG.
Note that the first and second non-grounded electrodes 2 and 3 used here are installed so that the areas of the opposed surfaces are substantially equal.
In FIG. 5, reference numeral 72 denotes a first connecting conductor plate, which is a conductor plate that electrically connects the first electrode 2 and the first rectangular plate conductor 61. Reference numeral 73 denotes a second connecting conductor plate, which is a conductor plate that electrically connects the second electrode 3 and the second rectangular plate-shaped conductor 62.
The first and second connection conductor plates 72 and 73 are respectively the vacuum side end portions of the first and second rectangular plate-like conductors 61 and 62 that are output portions of the current introduction terminal 40, and the first and second connection conductor plates 72 and 73, respectively. The feeding points 20 and 21 of the two electrodes are connected. As a result, the output of the high-frequency power supply 25 can be supplied to the feeding points 20 and 21 of the first and second electrodes 2 and 3 via the impedance matching unit 31, the balance-unbalance conversion device 33, and the current introduction terminal 40. it can.
The first and second connecting conductor plates 72 and 73 are made of thin conductor plates, so that the distance between the first and second rectangular plate conductors 61 and 62 and the first and second electrodes 2 are reduced. Even when the intervals of 3 are different, the electrical connection between them can be easily performed.
In FIG. 6, reference numerals 72 a and 73 a are first specific examples of the first and second connection conductors 72 and 73, and are made of thin triangular conductor plates with apexes cut off. Although the size depends on the electrode size, for example, the long side = 10 cm, the short side = 5 cm, the height = 5 cm, the thickness = 0.3 mm, and the material is steel, aluminum, copper, gold, silver, etc. A metal, for example, SUS304.
Note that the first and second rectangular plate conductors 61 are formed by using the first and second connection conductors 72a and 73a made of a thin triangular conductor plate with a vertex cut as shown in FIG. , 62 and the widths of the first and second electrodes 2 and 3 can be easily connected to each other.
Further, when the widths of the first and second electrodes 2 and 3 are wider than the widths of the first and second rectangular plate-like conductors 61 and 62, as will be described later, plasma for a large area substrate is used. Application of surface treatment becomes possible.
In FIG. 7, reference numerals 72 b and 73 b are second specific examples of the first and second connection conductors 72 and 73, and the long sides of the thin triangular conductor plate with the vertices cut out are the first and second. The short side is connected to the first and second rectangular plate conductors 61 and 62. Although the size depends on the electrode size, for example, the long side = 10 cm, the short side = 5 cm, the height = 5 cm, the thickness = 0.3 mm, and the material is steel, aluminum, copper, gold, silver, etc. A metal, for example, SUS304.
In addition, the 1st and 2nd rectangular plate-shaped conductor 61 is used by using the 1st and 2nd connection conductors 72b and 73b made from the triangular thin conductor board by which the vertex was cut as shown in FIG. , 62 and the widths of the first and second electrodes 2 and 3 can be easily connected to each other.
Further, when the widths of the first and second electrodes 2 and 3 are wider than the widths of the first and second rectangular plate-like conductors 61 and 62, as will be described later, plasma for a large area substrate is used. Application of surface treatment becomes possible.

Next, a characteristic selection test (referred to as a selection process) of the balanced transmission circuit 40 that is performed in advance when the amorphous Si for an a-Si solar cell is formed using the plasma surface treatment apparatus having the above configuration will be described. .
Here, specifically, one suitable for the following amorphous Si film forming conditions is selected from the three current introduction terminals 40a, 40b, and 40c.
The film formation conditions for amorphous Si are as follows.
(Film forming conditions)
● Discharge gas: SiH4,
● Flow rate: 500sccm,
● Pressure: 0.5 Torr (66.5 Pa),
● Electrode size: 70cm x 30cm,
● Electrode spacing: 2.5cm,
Connection of electrodes and current introduction terminals: first and second connection conductors 72a, 73a,
● Power supply frequency: 60 MHz
● Power: 800W
-Substrate temperature: 180 ° C.

1 to 7, first, for example, as the current introduction terminal 40 of FIG. 1, the length of the first current introduction terminal 40a, that is, the tubular conductor 60 = 10 cm (thickness = 1.5 cm), and the inner diameter = 14 cm (thickness = 1.5 cm), the length of the first and second rectangular plate conductors 61 and 62 = 14 cm, the width W = 5 cm (thickness 3 mm), and the distance h = 2.5 cm, that is, W / h = 2 and the current introduction terminal 40a having the characteristic impedance Z ₀ = about 30Ω is installed.
Next, the substrate 11 is previously placed on the second non-grounded electrode 3 and a vacuum pump (not shown) is operated to remove impurity gas and the like in the vacuum vessel 1, and then the SiH 4 gas is discharged from the discharge gas supply pipe 8. Is supplied at a pressure of 0.5 Torr (66.5 Pa), for example, and high-frequency power is supplied to the pair of electrodes 2 and 3, for example, power at a frequency of 60 MHz, for example, 800 W. The substrate temperature is kept in the range of 80 to 350 ° C., for example, 180 ° C.

That is, in FIG. 1, the output of the high frequency power supply 25 is set to 800 W at 60 MHz, for example, and the output is a coaxial cable 30, impedance matching unit 31, coaxial cable 32, unbalance conversion device 33, and current introduction terminal as a current introduction terminal 40. The power is supplied to the feeding points 20 and 21 of the first and second electrodes 2 and 3 through 40a.
In this case, the LC adjuster of the impedance matching unit 31 and the traveling wave and reflected wave power value monitors attached to the high-frequency power source 31 are used in combination to reflect the supplied power on the upstream side of the impedance matching unit 31. You can prevent the waves from returning.
However, when the impedance matching between the current introduction terminal 40a (characteristic impedance Z ₀ = about 30Ω) and the pair of electrodes 2 and 3 under the amorphous Si film forming condition is not good, a certain amount of reflected wave is generated. Come back. Assume that the reflected wave in the case of the first balanced transmission circuit 40 a is 30 W with respect to the output 800 W of the high frequency power supply 31, for example.
In addition, the phase difference of the voltage of the output of the balun 33 at the input part of the current introduction terminal 40a, that is, the atmospheric end of the first and second rectangular plate conductors 61 and 62 is 180 degrees. This is monitored by a voltage measuring device (not shown).
When electric power is supplied to the feeding points 20 and 21 of the first and second electrodes 2 and 3, plasma of SiH 4 gas is generated between the pair of electrodes 2 and 3. In this plasma generation, the pair of electrodes 2 and 3 have substantially the same area and are not grounded, and the power is different from the power supply points 20 and 21 by a voltage phase difference of 180 °, that is, the forward path. Since electric power having the same return current amplitude and a phase difference of 180 ° is supplied, abnormal discharge in the vicinity of the feeding points 20 and 21 is suppressed almost completely.
The reason why plasma is generated except between the pair of electrodes 2 and 3 is that the power transmission circuit supplied to the electrodes is leaked due to the unbalanced transmission circuit and one of the pair of electrodes is grounded. Leakage current generated by
In addition, the main cause of abnormal discharge in the vicinity of the feeding points 20 and 21 is that the power transmission circuit supplied to the electrodes is leaked due to the unbalanced transmission circuit and one of the pair of electrodes is grounded. The leakage current generated by

That is, in the power supply from the output portion of the current introduction terminal 40, that is, the vacuum side end portions of the first and second rectangular plate conductors 61 and 62 to the power supply points 20 and 21, the pair of electrodes 2 and 3 are Since it has the same electrical characteristics as a balanced transmission line similar to the current introduction terminal 40, the occurrence of leakage current is suppressed.
As a result, no abnormal discharge or local discharge occurs. Furthermore, as described above, since the phase difference between the voltages applied to the power supply points 20 and 21 is 180 degrees, that is, in a state where positive and negative voltages are applied to the pair of electrodes, There is no generation of plasma other than between three.
Therefore, there is no generation of plasma due to the leakage current related to the ground structure and wiring situation around the pair of electrodes, which is a problem in the prior art, and stable plasma generation with high reproducibility is possible.

However, when the impedance matching device 31 is arranged downstream of the balance-unbalance conversion device 33, that is, between the balance-unbalance conversion device 33 and the current introduction terminal 40, the LC built-in in the impedance matching device 31 is provided. Since the circuit is adjusted for impedance matching between the load, the power source, and the transmission path, the phase difference of the voltage applied to the current introduction terminal 40 cannot be secured at 180 degrees. Therefore, it is important that the place where the impedance matching device 31 is disposed is upstream of the balance-unbalance conversion device 18.
That is, the device configuration of the power supply circuit from the high-frequency power source 25 to the power supply points 20 and 21 of the pair of electrodes extends from the upstream side to the downstream side of the power flow from the high-frequency power source, the impedance matching device, Arranging in the order of the converter, the current introduction terminal, and the power supply point is important in order to ensure a voltage phase difference of 180 °.

Next, in the same manner as described above, in FIGS. 1 to 7, as the current introduction terminal 40 in FIG. , The inner diameter = 14 cm (thickness = 1.5 cm), the length of the first and second rectangular plate conductors 61, 62 = 14 cm, the width W = 5 cm (thickness 3 mm), and the distance h = 1 cm, that is, W A current introduction terminal 40b having a characteristic impedance / h = 5 and characteristic impedance Z ₀ = about 15Ω is installed.
Next, the substrate 11 is previously placed on the second non-grounded electrode 3 and a vacuum pump (not shown) is operated to remove impurity gas and the like in the vacuum vessel 1, and then the SiH 4 gas is discharged from the discharge gas supply pipe 8. Is supplied at a pressure of 0.5 Torr (66.5 Pa), for example, and high-frequency power is supplied to the pair of electrodes 2 and 3, for example, power at a frequency of 60 MHz, for example, 800 W. The substrate temperature is kept in the range of 80 to 350 ° C., for example, 180 ° C.

That is, in FIGS. 1 to 7, the output of the high frequency power supply 25 is set to 800 W at 60 MHz, for example, and the output is used as the coaxial cable 30, the impedance matching unit 31, the coaxial cable 32, the balance-unbalance conversion device 33, and the current introduction terminal 40. The power is supplied to the feeding points 20 and 21 of the first and second electrodes 2 and 3 through the current introduction terminal 40b.
In this case, the LC adjuster of the impedance matching unit 31 and the traveling wave and reflected wave power value monitors attached to the high-frequency power source 31 are used in combination to reflect the supplied power on the upstream side of the impedance matching unit 31. You can prevent the waves from returning.
However, when the impedance matching between the current introduction terminal 40b (characteristic impedance Z ₀ = about 25Ω) and the pair of electrodes 2 and 3 under the amorphous Si film forming condition is not good, a certain amount of reflected wave is generated. Come back. Assume that the reflected wave in the case of the first balanced transmission circuit 40b is 20 W with respect to the output 800 W of the high frequency power supply 31, for example.
Further, the phase difference of the voltage of the output of the balun 33 is 180 degrees at the input part of the current introduction terminal 40b, that is, at the end of the first and second rectangular plate conductors 61 and 62 on the atmosphere side. This is monitored by a voltage measuring device (not shown).
When electric power is supplied to the feeding points 20 and 21 of the first and second electrodes 2 and 3, plasma of SiH 4 gas is generated between the pair of electrodes 2 and 3. In this plasma generation, the pair of electrodes 2 and 3 have substantially the same area and are not grounded, and the power is different from the power supply points 20 and 21 by a voltage phase difference of 180 °, that is, the forward path. Since electric power having the same return current amplitude and a phase difference of 180 ° is supplied, abnormal discharge in the vicinity of the feeding points 20 and 21 is suppressed almost completely.
The reason why plasma is generated except between the pair of electrodes 2 and 3 is that the power transmission circuit supplied to the electrodes is leaked due to the unbalanced transmission circuit and one of the pair of electrodes is grounded. Leakage current generated by
In addition, the main cause of abnormal discharge in the vicinity of the feeding points 20 and 21 is that the power transmission circuit supplied to the electrodes is leaked due to the unbalanced transmission circuit and one of the pair of electrodes is grounded. The leakage current generated by

Next, in the same manner as described above, in FIGS. 1 to 7, as the current introduction terminal 40 of FIG. 1, the length of the third current introduction terminal 40c, that is, the tubular conductor 60 = 10 cm (thickness = 1.5 cm). The inner diameter = 14 cm (thickness = 1.5 cm), the length of the first and second rectangular plate conductors 61, 62 = 14 cm, the width W = 5 cm (thickness 3 mm), and the distance h = 0.5 cm, , W / h = 10, and a balanced transmission circuit 40c having characteristics of characteristic impedance Z ₀ = about 10Ω is installed.
Next, the substrate 11 is previously placed on the second non-grounded electrode 3 and a vacuum pump (not shown) is operated to remove impurity gas and the like in the vacuum vessel 1, and then the SiH 4 gas is discharged from the discharge gas supply pipe 8. Is supplied at a pressure of 0.5 Torr (66.5 Pa), for example, and high-frequency power is supplied to the pair of electrodes 2 and 3, for example, power at a frequency of 60 MHz, for example, 800 W. The substrate temperature is kept in the range of 80 to 350 ° C., for example, 180 ° C.

That is, in FIGS. 1 to 7, the output of the high frequency power supply 25 is set to 800 W at 60 MHz, for example, and the output is used as the coaxial cable 30, the impedance matching unit 31, the coaxial cable 32, the balance-unbalance conversion device 33, and the current introduction terminal 40. The current is supplied to the feeding points 20 and 21 of the first and second electrodes 2 and 3 through the current introduction terminal 40c.
In this case, the LC adjuster of the impedance matching unit 31 and the traveling wave and reflected wave power value monitors attached to the high-frequency power source 31 are used in combination to reflect the supplied power on the upstream side of the impedance matching unit 31. You can prevent the waves from returning.
However, when the impedance matching between the 40c (characteristic impedance Z ₀ = about 15Ω) and the pair of electrodes 2 and 3 under the amorphous Si film forming condition is not good, a certain amount of reflected wave returns. . It is assumed that the reflected wave in the case of the first current introduction terminal 40c is 25 W with respect to the output 800 W of the high frequency power supply 31, for example.
Further, the phase difference of the voltage of the output of the balun 33 is 180 degrees at the input part of the current introduction terminal 40c, that is, at the end on the atmosphere side of the first and second rectangular plate conductors 61 and 62. This is monitored by a voltage measuring device (not shown).
When electric power is supplied to the feeding points 20 and 21 of the first and second electrodes 2 and 3, plasma of SiH 4 gas is generated between the pair of electrodes 2 and 3. In this plasma generation, the pair of electrodes 2 and 3 have substantially the same area and are not grounded, and the power is different from the power supply points 20 and 21 by a voltage phase difference of 180 °, that is, the forward path. Since electric power having the same return current amplitude and a phase difference of 180 ° is supplied, abnormal discharge in the vicinity of the feeding points 20 and 21 is suppressed almost completely.
The reason why plasma is generated except between the pair of electrodes 2 and 3 is that the power transmission circuit supplied to the electrodes is leaked due to the unbalanced transmission circuit and one of the pair of electrodes is grounded. Leakage current generated by
In addition, the main cause of abnormal discharge in the vicinity of the feeding points 20 and 21 is that the power transmission circuit supplied to the electrodes is leaked due to the unbalanced transmission circuit and one of the pair of electrodes is grounded. The leakage current generated by

As a result of the selection test of the current introduction terminal 40, in the above case, the magnitude of the reflected wave is 30W at the current introduction terminal 40a, 20W at the current introduction terminal 40b, and 25W at the current introduction terminal 40c.
In this case, a current introduction terminal 40b that can create a condition with the least number of reflected waves is selected.

Next, in response to the result of the selection test of the current introduction terminal 40, the process proceeds to the film forming process. As the current introduction terminal 40, the current introduction terminal 40b which is the best in suppressing the reflected wave with respect to the amorphous Si film forming condition is adopted.
Then, the substrate 11 is previously set on the second non-grounded electrode 3 and a vacuum pump (not shown) is operated to remove impurity gas and the like in the vacuum vessel 1. For example, while supplying at 500 sccm and a pressure of 0.5 Torr (66.5 Pa), high-frequency power, for example, power at a frequency of 60 MHz, for example, 800 W is supplied to the pair of electrodes 2 and 3. The substrate temperature is kept in the range of 80 to 350 ° C., for example, 180 ° C.

That is, in FIGS. 1 to 3 and 6, the output of the high frequency power supply 25 is set to 800 W at 60 MHz, for example, and the output is the coaxial cable 30, impedance matching unit 31, coaxial cable 32, balun The power is supplied to the feeding points 20 and 21 of the first and second electrodes 2 and 3 via 40b.
In this case, the LC adjuster of the impedance matching unit 31 and the traveling wave and reflected wave power value monitors attached to the high-frequency power source 31 are used in combination to reflect the supplied power on the upstream side of the impedance matching unit 31. You can prevent the waves from returning.
However, when the impedance matching between the current introduction terminal 40b (characteristic impedance Z ₀ = about 15Ω) and the pair of electrodes 2 and 3 under the amorphous Si film forming condition is not good, a certain amount of reflected wave is generated. Come back. Here, it is the same as the result of the selection step, and is about 20 W with respect to the output 800 W of the high frequency power supply 31.
Further, the phase difference of the voltage of the output of the balun 33 is 180 degrees at the input portion of the current introduction terminal 40, that is, at the end of the first and second rectangular plate conductors 61 and 62 on the atmosphere side. This is monitored by a voltage measuring device (not shown).
When electric power is supplied to the feeding points 20 and 21 of the first and second electrodes 2 and 3, plasma of SiH 4 gas is generated between the pair of electrodes 2 and 3. In this plasma generation, the pair of electrodes 2 and 3 have substantially the same area and are not grounded, and the power is different from the power supply points 20 and 21 by a voltage phase difference of 180 °, that is, the forward path. Since electric power having the same return current amplitude and a phase difference of 180 ° is supplied, abnormal discharge in the vicinity of the feeding points 20 and 21 is completely suppressed.
The reason why plasma is generated except between the pair of electrodes 2 and 3 is that the power transmission circuit supplied to the electrodes is leaked due to the unbalanced transmission circuit and one of the pair of electrodes is grounded. Leakage current generated by
In addition, the main cause of abnormal discharge in the vicinity of the feeding points 20 and 21 is that the power transmission circuit supplied to the electrodes is leaked due to the unbalanced transmission circuit and one of the pair of electrodes is grounded. The leakage current generated by

That is, in the power supply from the output portion of the current introduction terminal 40, that is, the vacuum side end portions of the first and second rectangular plate conductors 61 and 62 to the power supply points 20 and 21, the pair of electrodes 2 and 3 are Since it has the same electrical characteristics as a balanced transmission line similar to the current introduction terminal 40, the occurrence of leakage current is suppressed.
As a result, no abnormal discharge or local discharge occurs. Further, as described above, since the phase difference between the voltages applied to the power supply points 20 and 21 is 180 °, that is, since a positive and negative voltage is applied to the pair of electrodes, the electrodes 2 and 3 There is no generation of plasma outside the gap.
Therefore, there is no generation of plasma due to the leakage current related to the ground structure and wiring situation around the pair of electrodes, which is a problem in the prior art, and stable plasma generation with high reproducibility is possible.

  However, when the impedance matching device 31 is arranged downstream of the balance-unbalance conversion device 33, that is, between the balance-unbalance conversion device 33 and the current introduction terminal 40, the LC built-in in the impedance matching device 31 is provided. Since the circuit is adjusted for impedance matching between the load, the power source, and the transmission line, the phase difference of the voltage applied to the current introduction terminal 40 cannot be secured at 180 °. Therefore, it is important that the place where the impedance matching device 31 is disposed is upstream of the balance-unbalance conversion device 33.

In the above process, when SiH 4 gas is turned into plasma, 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 12, thereby depositing an a-Si film. To do.
It is a well-known technique that microcrystalline Si, thin-film polycrystalline Si, or the like can be formed by optimizing the flow ratio, pressure, and power of SiH4 and H2 in the film forming conditions.

  Specific conditions in the case of film formation by the above procedure will be described below. A-Si having a film forming speed of 1 nm / s and a film thickness distribution of ± 10% is formed on a glass substrate 11 having a size of about 700 mm × 300 mm (thickness 3 mm).

The film forming conditions are as follows.
(Film forming conditions)
● Discharge gas: SiH4,
● Flow rate: 500sccm,
● Pressure: 0.5 Torr (66.5 Pa),
● Electrode size: 70cm x 30cm,
● Electrode spacing: 2.5cm,
Connection of electrodes and current introduction terminals: first and second connection conductors 70a, 71a,
● Power supply frequency: 60 MHz
● Power: 800W
-Substrate temperature: 180 ° C.

When plasma is generated under the above-mentioned film forming conditions, the output of the high-frequency power supply 25 is transmitted to the balance-unbalance conversion device 33 via the coaxial cable 30 and the impedance matching unit 31 which are unbalanced transmission circuits, and the transmitted power is balanced. Since it is converted into balanced power by the unbalanced converter 33 and can be supplied to the power supply points 20 and 21 of the pair of electrodes 2 and 3 through the current introduction terminal 40 having the characteristics of a balanced transmission circuit, the power supply system and the load Transmission characteristics at a connection portion with a certain pair of electrodes are matched, and generation of leakage current is suppressed.
Therefore, the spatial distribution of the density of the generated plasma is uniform with good reproducibility compared to the conventional case. As a result, the film thickness distribution of the a-Si film to be formed becomes uniform with good reproducibility compared to the conventional case. Numerically, film formation is possible when the a-Si film thickness distribution is within ± 10%.

A balanced transmission circuit (or balanced transmission line) is a transmission form in which a current flowing through both lines is equal in amplitude and phase is 180 ° different in a power transmission circuit composed of two conductors. It is.
In addition, the LC bridge type unbalanced conversion device used in this embodiment is means for converting the power transmission of the unbalanced transmission method input to the device into the balanced transmission method. Thus, a super-top type balance-unbalance converter, a half-wavelength bypass type balance-unbalance converter, and the like can be used. Also, a device combining a power distributor and a phase shifter can be used.

Further, in this embodiment, since the feeding point is set to one point (a pair) for each of the pair of electrodes 2 and 3, the substrate size is limited to about 700 mm × 300 mm. However, if the number of feeding points is increased, the width of the size is increased. It is natural that it can be expanded.
In addition, if a plurality of pairs of electrodes are installed and a plurality of the above-described power supply systems are arranged according to the number of the electrodes, it is natural that the width of the substrate size can be expanded.

Further, in the manufacture of a-Si solar cells, thin film transistors, and photosensitive drums, there is no problem in performance as long as the film thickness distribution is within ± 10%. According to the above embodiment, it is possible to obtain a remarkably good film thickness distribution as compared with the conventional apparatus and method even when a power supply frequency of 60 MHz is used.
This means that the industrial value related to productivity improvement and cost reduction in the manufacturing field of a-Si solar cells, thin film transistors, and photosensitive drums is remarkably large.

(Example 3)
A current introduction terminal, a plasma surface treatment apparatus (plasma CVD apparatus) and a plasma surface treatment method (plasma CVD method) having the current introduction terminal according to the third embodiment of the present invention will be described with reference to FIGS. I will explain. Moreover, FIG. 1 is referred as needed.

  FIG. 8 is a conceptual diagram showing the connection means between the current introduction terminal and the electrode according to the third embodiment of the present invention, and FIG. 9A is a current introduction using a rectangular tube according to the third embodiment of the present invention. FIG. 9B is an explanatory view showing the external appearance of the terminal, and FIG. 9B is an explanatory view showing the external appearance of the current introduction terminal using the circular tube according to the third embodiment of the present invention.

First, the configuration of the current introduction terminal according to the third embodiment of the present invention will be described. However, the same members as those shown in FIG. 1 to FIG.
8 and 9, reference numeral 400 denotes a current introduction terminal provided with a tubular conductor having a rectangular cross-sectional shape. As shown in FIGS. 8 and 9, the current introduction terminal 400 includes a rectangular tubular conductor 60a, a flange 65a, a first rectangular plate conductor 61a, a second rectangular plate conductor 62a, and a first rectangular conductor 60a. It consists of a dielectric 63a and a second dielectric 64a.
As the first and second dielectrics 63a and 64a, silicon oxide SiO2 (relative dielectric constant = about 4), silicon nitride SiN4 (relative dielectric constant = about 7) and alumina Al2O3 (relative dielectric constant = 8.5-11) ) And other ceramics. Here, for example, alumina having a relative dielectric constant of 10 is used.
A flange 65a used for joining to the vacuum vessel 1 is fixed to one end of the tubular conductor 60a. Further, connection conductors 72a and 73a used for connection to the first and second electrodes 2 and 3 are fixed to one end portions of the first and second rectangular plate conductors 61a and 62a. .
8 and 9, the current introduction terminal 400 is installed in the vacuum vessel 1 through the flange 65 a of the tubular conductor 60 a constituting the current introduction terminal 400. At this time, the current introduction terminal 400 is installed so that one end is on the atmosphere side and the other is on the vacuum side. The space between the vacuum vessel 1 and the flange 65a of the current introduction terminal 400 is kept airtight by an O-ring. The tubular conductor 60 a is supported by the vacuum vessel 1 with a tubular conductor support conductor 67.

Here, the interval h at both ends of the first rectangular plate conductor 61a and the second rectangular plate conductor 62a is set to a different value. That is, the first dielectric 63a in the first rectangular plate conductor 61a and the second rectangular plate conductor 62a has a wedge shape.
Here, as a first specific example, the length of the rectangular tubular conductor 60a is 10 cm, and the cross-sectional arrangement of the first rectangular plate-shaped conductor 61a and the second rectangular plate-shaped conductor 62a at the end on the atmosphere side is as follows. In the inner dimension 14 cm × 14 cm (thickness = 1.5 cm) of the rectangular tubular conductor 60 a, the length of the first and second rectangular plate-like conductors 61 a and 62 a = 14 cm, the width W = 5 cm (thickness 3 mm), and the distance between them h = 2.5 cm, that is, W / h = 2. This set value has the meaning of characteristic impedance Z ₀ = about 30Ω from FIG.
The cross-sectional arrangement of the first rectangular plate-like conductor 61a and the second rectangular plate-like conductor 62a at the end on the vacuum side is within the width 10 W × 10 cm (thickness = 1.5 cm) of the rectangular tubular conductor 60a. = 5 cm (thickness 3 mm), the interval h = 1 cm, that is, W / h = 5. This set value has the meaning of characteristic impedance Z ₀ = about 15Ω from FIG.
That is, in the case of this first specific example, the characteristic impedance Z ₀ at the input part of the current introduction terminal 400 is about 30Ω, and the characteristic impedance Z ₀ at the output part is about 15Ω. Distribution, that is, a current introduction terminal having a tapered distribution.

As a second specific example, the length of the rectangular tubular conductor 60a is 10 cm, and the cross-sectional arrangement of the first rectangular plate-shaped conductor 61a and the second rectangular plate-shaped conductor 62a at the end on the atmosphere side is as follows. The inner dimension of the rectangular tubular conductor 60a is 14 cm × 14 cm (thickness = 1.5 cm), the length of the first and second rectangular plate-like conductors 61 and 62 is 14 cm, the width W = 5 cm (thickness 3 mm), and the distance h = 2. Set to 5 cm, ie, W / h = 2. This set value has the meaning of characteristic impedance Z ₀ = about 30Ω from FIG.
The cross-sectional arrangement of the first rectangular plate conductor 61a and the second rectangular plate conductor 62a at the end on the vacuum side is such that the inner dimension of the rectangular tubular conductor 60a is 10 cm × 10 cm (thickness = 1.5 cm), and the width W = 5 cm ( The thickness is set to 3 mm) and the interval h = 0.5 cm, that is, W / h = 10. This set value has the meaning of characteristic impedance Z ₀ = about 10Ω from FIG.
That is, in the case of this second specific example, the characteristic impedance Z ₀ at the input portion of the current introduction terminal 400 is about 30Ω, and the characteristic impedance Z ₀ at the output portion is about 10Ω is a taper type characteristic impedance. It can be said that the current introduction terminals are distributed.

8 and 9, reference numeral 401 denotes a current introduction terminal provided with a tubular conductor having a circular cross section. The current introduction terminal 401 (here, the balanced transmission circuit and the balanced transmission line are used as the same meaning) includes a circular tubular conductor 60b, a flange 65b, and a first rectangular plate shape as shown in FIGS. A conductor 61b, a second rectangular plate conductor 62b, a first dielectric 63b, and a second dielectric 64b are included.
As the first and second dielectrics 63b and 64b, silicon oxide SiO2 (relative dielectric constant = about 4), silicon nitride SiN4 (relative dielectric constant = about 7), and alumina Al2O3 (relative dielectric constant = 8.5-11) ) And other ceramics. Here, for example, alumina having a relative dielectric constant of 10 is used.
A flange 65b used for joining with the vacuum vessel 1 is fixed to one end of the tubular conductor 60b. Also, connection conductors 72a and 73a used for connection to the first and second electrodes 2 and 3 are fixed to one end of the first and second rectangular plate-like conductors 61b and 62b. .
8 and 9, the current introduction terminal 401 is installed in the vacuum vessel 1 through the flange 65 b of the tubular conductor 60 b constituting the current introduction terminal 401. At this time, one end of the current introduction terminal 401 is installed on the atmosphere side, and the other is installed on the vacuum side. The space between the vacuum vessel 1 and the flange 65b of the current introduction terminal 401 is kept airtight by an O-ring. The tubular conductor 60 b is supported on the vacuum vessel 1 by a tubular conductor support conductor 67.

Here, the interval h at both ends of the first rectangular plate conductor 61b and the second rectangular plate conductor 62b is set to a different value. That is, the first dielectric 63b existing between the first rectangular plate conductor 61b and the second rectangular plate conductor 62b has a wedge shape.
Here, as a first specific example, the length of the circular tubular conductor 60b is 10 cm, and the cross-sectional arrangement of the first rectangular plate-like conductor 61b and the second rectangular plate-like conductor 62b at the end on the atmosphere side The inner dimensions of the circular tubular conductor 60a are 14 cm in diameter (thickness = 1.5 cm), the lengths of the first and second rectangular plate conductors 61b and 62b are 14 cm, the width W = 5 cm (thickness 3 mm), and the distance between them. h = 2.5 cm, that is, W / h = 2. This set value has the meaning of characteristic impedance Z ₀ = about 30Ω from FIG.
The cross-sectional arrangement of the first rectangular plate conductor 61b and the second rectangular plate conductor 62b at the end on the vacuum side is such that the inner dimension of the circular tubular conductor 60a is 10 cm in diameter (thickness = 1.5 cm). The width W = 5 cm (thickness 3 mm) and the interval h = 1 cm, that is, W / h = 5 are set. This set value has the meaning of characteristic impedance Z ₀ = about 15Ω from FIG.
That is, in the case of this first specific example, the characteristic impedance Z ₀ at the input part of the current introduction terminal 401 is about 30Ω, and the characteristic impedance Z ₀ at the output part is about 15Ω, and the characteristic impedance is inclined. Distribution, that is, a current introduction terminal having a tapered distribution.

As a second specific example, the length of the circular tubular conductor 60a is 10 cm, and the cross-sectional arrangement of the first rectangular plate conductor 61b and the second rectangular plate conductor 62b at the end on the atmosphere side is as follows. The inside dimension of the circular tubular conductor 60a is 14 cm in diameter (thickness = 1.5 cm), the length of the first and second rectangular plate conductors 61b, 62b = 14 cm, the width W = 5 cm (thickness 3 mm), The interval h is set to 2.5 cm, that is, W / h = 2. This set value has the meaning of characteristic impedance Z ₀ = about 30Ω from FIG.
The cross-sectional arrangement of the first rectangular plate conductor 61b and the second rectangular plate conductor 62b at the end on the vacuum side is such that the inner dimension of the rectangular tubular conductor 60a is 10 cm in diameter (thickness = 1.5 cm). The width W = 5 cm (thickness 3 mm) and the interval h = 0.5 cm, that is, W / h = 10 are set. This set value has the meaning of characteristic impedance Z ₀ = about 10Ω from FIG.
That is, in the case of this second specific example, the characteristic impedance Z ₀ at the input part of the current introduction terminal 401 is about 30Ω, and the characteristic impedance Z ₀ at the output part is about 10Ω. Distribution, that is, a balanced transmission circuit having a tapered distribution.

Next, a characteristic selection test (referred to as a selection process) of the current introduction terminal 40 that is performed in advance when the amorphous Si for an a-Si solar cell is formed using the plasma surface treatment apparatus having the above configuration will be described. .
However, in order to avoid complicating the description, in the following description, the current introduction terminal including the tubular conductor having the rectangular cross section and the current introduction terminal including the tubular conductor having the circular cross section are used. Of the two, the former will be described as an example.
Specifically, the current introduction terminal 400 having a tubular conductor having a rectangular cross-sectional shape is suitable for the following amorphous Si film formation conditions from the first specific example and the second specific example. Select one.
In the case of the first specific example of the current introduction terminal 400 having a tubular conductor having a rectangular cross section, the characteristic impedance Z ₀ at the input part of the current introduction terminal 400 is about 30Ω, The characteristic impedance Z ₀ is a current introduction terminal whose characteristic impedance having a characteristic of about 15Ω is a tapered distribution.
Further, in the case of the second specific example of the current introduction terminal 400 having a tubular conductor having a rectangular cross section, the characteristic impedance Z ₀ at the input portion of the current introduction terminal 400 is about 30Ω, This is a current introduction terminal whose characteristic impedance having a characteristic impedance Z ₀ of about 10Ω is a tapered distribution.
The film formation conditions for amorphous Si are as follows.
(Film forming conditions)
● Discharge gas: SiH4,
● Flow rate: 500sccm,
● Pressure: 0.5 Torr (66.5 Pa),
● Electrode size: 70cm x 30cm,
● Electrode spacing: 2.5cm,
Connection of electrodes and current introduction terminals: first and second connection conductors 72a, 73a,
● Power supply frequency: 60 MHz
● Power: 800W
-Substrate temperature: 180 ° C.

In FIG. 1, FIG. 8, and FIG. 9, first, the current introduction terminal 400 in the case of the first specific example is installed. That is, a current introduction terminal having a characteristic impedance taper-type distribution in which the characteristic impedance Z ₀ at the input portion of the current introduction terminal 400 is about 30Ω and the characteristic impedance Z ₀ at the output portion is about 15Ω is installed. .
Next, the substrate 11 is previously placed on the second non-grounded electrode 3 and a vacuum pump (not shown) is operated to remove impurity gas and the like in the vacuum vessel 1, and then the SiH 4 gas is discharged from the discharge gas supply pipe 8. Is supplied at a pressure of 0.5 Torr (66.5 Pa), for example, and high-frequency power is supplied to the pair of electrodes 2 and 3, for example, power at a frequency of 60 MHz, for example, 800 W. The substrate temperature is kept in the range of 80 to 350 ° C., for example, 180 ° C.

That is, in FIG. 1, the output of the high frequency power supply 25 is set to 800 W at 60 MHz, for example, and the output is a coaxial cable 30, impedance matching unit 31, coaxial cable 32, unbalance conversion device 33, and current introduction terminal as a current introduction terminal 40. The power is supplied to the feeding points 20 and 21 of the first and second electrodes 2 and 3 via 400.
In this case, the LC adjuster of the impedance matching unit 31 and the traveling wave and reflected wave power value monitors attached to the high-frequency power source 31 are used in combination to reflect the supplied power on the upstream side of the impedance matching unit 31. You can prevent the waves from returning.
However, when the impedance matching between the current introduction terminal 400 (characteristic impedance Z ₀ = taper type) in the case of the first specific example and the pair of electrodes 2 and 3 under the amorphous Si film forming conditions is not good. Will return a certain amount of reflected waves. It is assumed that the reflected wave when the first current introduction terminal 400 is used is, for example, 30 W with respect to the output 800 W of the high frequency power supply 31.
In addition, the output of the balance-unbalance conversion device 33 at the input portion of the current introduction terminal 400 in the case of the first specific example, that is, the end portions on the atmosphere side of the first and second rectangular plate conductors 61a and 62a. The fact that the phase difference of the voltage is 180 ° is monitored by a voltage measuring device (not shown).
When electric power is supplied to the feeding points 20 and 21 of the first and second electrodes 2 and 3, plasma of SiH 4 gas is generated between the pair of electrodes 2 and 3. In this plasma generation, the pair of electrodes 2 and 3 have substantially the same area and are not grounded, and the power is different from the power supply points 20 and 21 by a voltage phase difference of 180 °, that is, the forward path. Since electric power having the same return current amplitude and a phase difference of 180 ° is supplied, abnormal discharge in the vicinity of the feeding points 20 and 21 is suppressed almost completely.

That is, the power supply from the output portion of the current introduction terminal 400 in the case of the first specific example, that is, the vacuum side end portions of the first and second rectangular plate conductors 61 and 62 to the power supply points 20 and 21. The pair of electrodes 2 and 3 have the same electrical characteristics as a balanced transmission line as the current introduction terminal 40, so that the generation of leakage current is suppressed.
As a result, no abnormal discharge or local discharge occurs. Further, as described above, since the phase difference between the voltages applied to the power supply points 20 and 21 is 180 °, that is, since a positive and negative voltage is applied to the pair of electrodes, the electrodes 2 and 3 There is no generation of plasma outside the gap.
Therefore, there is no generation of plasma due to the leakage current related to the ground structure and wiring situation around the pair of electrodes, which is a problem in the prior art, and stable plasma generation with high reproducibility is possible.

However, when the impedance matching device 31 is arranged downstream of the balance-unbalance conversion device 33, that is, between the balance-unbalance conversion device 33 and the current introduction terminal 400, the impedance matching device 31 has a built-in LC. Since the circuit is adjusted for impedance matching between the load, the power source, and the transmission path, the phase difference of the voltage applied to the current introduction terminal 400 cannot be secured at 180 degrees. Therefore, it is important that the place where the impedance matching device 31 is disposed is upstream of the balance-unbalance conversion device 33.
That is, the device configuration of the power supply circuit from the high-frequency power source 25 to the power feeding points 20 and 21 of the pair of electrodes is from the upstream side to the downstream side of the power flow. Arranging in the order of the converter, the current introduction terminal, and the power supply point is important in order to ensure a voltage phase difference of 180 degrees.

Next, in the same manner as described above, the current introduction terminal 401 in the case of the second specific example is installed in FIGS. That is, the current introduction terminal having a characteristic distribution in which the characteristic impedance Z ₀ at the input portion of the current introduction terminal 401 is about 30Ω and the characteristic impedance Z ₀ at the output portion is about 10Ω is a taper type distribution. .
Next, the substrate 11 is previously placed on the second non-grounded electrode 3 and a vacuum pump (not shown) is operated to remove impurity gas and the like in the vacuum vessel 1, and then the SiH 4 gas is discharged from the discharge gas supply pipe 8. Is supplied at a pressure of 0.5 Torr (66.5 Pa), for example, and high-frequency power is supplied to the pair of electrodes 2 and 3, for example, power at a frequency of 60 MHz, for example, 800 W. The substrate temperature is kept in the range of 80 to 350 ° C., for example, 180 ° C.

That is, in FIGS. 1, 8, and 9, the output of the high frequency power supply 25 is set to 800 W at 60 MHz, for example, and the output is the coaxial cable 30, the impedance matching unit 31, the coaxial cable 32, the balance-unbalance conversion device 33, and the current introduction terminal. The power is supplied to the feeding points 20 and 21 of the first and second electrodes 2 and 3 via 401.
In this case, the LC adjuster of the impedance matching unit 31 and the traveling wave and reflected wave power value monitors attached to the high-frequency power source 31 are used in combination to reflect the supplied power on the upstream side of the impedance matching unit 31. You can prevent the waves from returning.
However, when the impedance matching between the current introduction terminal 401 (characteristic impedance Z ₀ = taper type) in the case of the second specific example and the pair of electrodes 2 and 3 under the amorphous Si film forming conditions is not good. Will return a certain amount of reflected waves. It is assumed that the reflected wave when the first current introduction terminal 401 is used is 20 W with respect to the output 800 W of the high frequency power supply 31, for example.
In addition, the output of the balance-unbalance conversion device 33 at the input portion of the current introduction terminal 401 in the case of the second specific example, that is, at the end on the atmosphere side of the first and second rectangular plate-like conductors 61 and 62, is output. The fact that the phase difference of the voltage is 180 ° is monitored by a voltage measuring device (not shown).
When electric power is supplied to the feeding points 20 and 21 of the first and second electrodes 2 and 3, plasma of SiH 4 gas is generated between the pair of electrodes 2 and 3. In this plasma generation, the pair of electrodes 2 and 3 have substantially the same area and are not grounded, and the power is different from the power supply points 20 and 21 by a voltage phase difference of 180 °, that is, the forward path. Since electric power having the same return current amplitude and a phase difference of 180 ° is supplied, abnormal discharge in the vicinity of the feeding points 20 and 21 is suppressed almost completely.

As a result of the selection test of the current introduction terminal 40, the magnitude of the reflected wave is 30 W in the case of the first specific example 400 and 20 W in the case of the second specific example 401.
In this case, the current introduction terminal 400 in the case of the second specific example 401 capable of creating a condition with few reflected waves is selected.

Next, in response to the result of the selection test of the current introduction terminals 400 and 401, the process proceeds to the film forming process. In FIG. 1, as the current introduction terminal 40, the current introduction terminal 401 in the case of the second specific example which is the best in terms of suppression of reflected waves with respect to the amorphous Si film forming condition is employed.
Then, the substrate 11 is previously set on the second non-grounded electrode 3 and a vacuum pump (not shown) is operated to remove impurity gas and the like in the vacuum vessel 1. For example, while supplying at 500 sccm and a pressure of 0.5 Torr (66.5 Pa), high-frequency power, for example, power at a frequency of 60 MHz, for example, 800 W is supplied to the pair of electrodes 2 and 3. The substrate temperature is kept in the range of 80 to 350 ° C., for example, 180 ° C.

That is, in FIGS. 1, 6 and 8, the output of the high frequency power supply 25 is set to 800 W at 60 MHz, for example, and the output is the coaxial cable 30, the impedance matching unit 31, the coaxial cable 32, the balance-unbalance conversion device 33, and the second. The power supply points 20 and 21 of the first and second electrodes 2 and 3 are supplied via the current introduction terminal 401 of the specific example.
In this case, the LC adjuster of the impedance matching unit 31 and the traveling wave and reflected wave power value monitors attached to the high-frequency power source 31 are used in combination to reflect the supplied power on the upstream side of the impedance matching unit 31. You can prevent the waves from returning.
However, when the combination of the current introduction terminal 401 (characteristic impedance Z ₀ = taper type) of the second specific example and the pair of electrodes 2 and 3 under the amorphous Si film forming conditions is not good in impedance matching, Some reflected waves will come back. Here, it is the same as the result of the selection step, and is about 20 W with respect to the output 800 W of the high frequency power supply 31.
Further, the phase difference of the voltage of the output of the balun 33 is 180 ° at the input portion of the current introduction terminal 401, that is, at the end of the first and second rectangular plate conductors 61a and 62a on the atmosphere side. This is monitored by a voltage measuring device (not shown).
When electric power is supplied to the feeding points 20 and 21 of the first and second electrodes 2 and 3, plasma of SiH 4 gas is generated between the pair of electrodes 2 and 3. In this plasma generation, the pair of electrodes 2 and 3 have substantially the same area and are not grounded, and the power is different from the power supply points 20 and 21 by a voltage phase difference of 180 °, that is, the forward path. Since electric power having the same return current amplitude and a phase difference of 180 ° is supplied, abnormal discharge in the vicinity of the feeding points 20 and 21 is completely suppressed.
The reason why plasma is generated except between the pair of electrodes 2 and 3 is that the power transmission circuit supplied to the electrodes is leaked due to the unbalanced transmission circuit and one of the pair of electrodes is grounded. Leakage current generated by
In addition, the main cause of abnormal discharge in the vicinity of the feeding points 20 and 21 is that the power transmission circuit supplied to the electrodes is leaked due to the unbalanced transmission circuit and one of the pair of electrodes is grounded. The leakage current generated by

That is, in the power supply from the output portion of the current introduction terminal 401, that is, the vacuum side end portions of the first and second rectangular plate conductors 61 and 62 to the power supply points 20 and 21, the pair of electrodes 2 and 3 are Since it has the same electrical characteristics as a balanced transmission line similar to the current introduction terminal 401, the occurrence of leakage current is suppressed.
As a result, no abnormal discharge or local discharge occurs. Further, as described above, since the phase difference between the voltages applied to the power supply points 20 and 21 is 180 °, that is, since a positive and negative voltage is applied to the pair of electrodes, the electrodes 2 and 3 There is no generation of plasma outside the gap.
Therefore, there is no generation of plasma due to the leakage current related to the ground structure and wiring situation around the pair of electrodes, which is a problem in the prior art, and stable plasma generation with high reproducibility is possible.

  However, when the impedance matching device 31 is arranged downstream of the balance-unbalance conversion device 33, that is, between the balance-unbalance conversion device 33 and the current introduction terminal 401, the impedance matching device 31 has a built-in LC. Since the circuit is adjusted for impedance matching between the load, the power source, and the transmission path, the phase difference of the voltage applied to the balanced transmission circuit 40 cannot be secured at 180 °. Therefore, it is important that the place where the impedance matching device 31 is disposed is upstream of the balance-unbalance conversion device 33.

In the above process, when SiH 4 gas is turned into plasma, 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 12, thereby depositing an a-Si film. To do.
It is a well-known technique that microcrystalline Si, thin-film polycrystalline Si, or the like can be formed by optimizing the flow ratio, pressure, and power of SiH4 and H2 in the film forming conditions.

  Specific conditions in the case of film formation by the above procedure will be described below. A-Si having a film forming speed of 1 nm / s and a film thickness distribution of ± 10% is formed on a glass substrate 11 having a size of about 700 mm × 300 mm (thickness 3 mm).

The film forming conditions are as follows.
(Film forming conditions)
● Discharge gas: SiH4,
● Flow rate: 500sccm,
● Pressure: 0.5 Torr (66.5 Pa),
● Electrode size: 70cm x 30cm,
● Electrode spacing: 2.5cm,
Connection of electrodes and current introduction terminals: first and second connection conductors 72a, 73a,
● Power supply frequency: 60 MHz
● Power: 800W
-Substrate temperature: 180 ° C.

When plasma is generated under the above-mentioned film forming conditions, the output of the high-frequency power supply 25 is transmitted to the balance-unbalance conversion device 33 via the coaxial cable 30 and the impedance matching unit 31 which are unbalanced transmission circuits, and the transmitted power is balanced. Since it can be converted into balanced power by the unbalanced converter 33 and supplied to the power supply points 20 and 21 of the pair of electrodes 2 and 3 via the current introduction terminal 401 of the balanced transmission circuit, a pair of power supply system and load Transmission characteristics at the connection with the electrode are matched, and the occurrence of leakage current is suppressed.
Therefore, the spatial distribution of the density of the generated plasma is uniform with good reproducibility compared to the conventional case. As a result, the film thickness distribution of the a-Si film to be formed becomes uniform with good reproducibility compared to the conventional case. Numerically, film formation is possible when the a-Si film thickness distribution is within ± 10%.

A balanced transmission circuit (or balanced transmission line) is a transmission form in which a current flowing through both lines is equal in amplitude and phase is 180 ° different in a power transmission circuit composed of two conductors. It is.
In addition, the LC bridge type unbalanced conversion device used in this embodiment is means for converting the power transmission of the unbalanced transmission method input to the device into the balanced transmission method. Thus, a super-top type balance-unbalance converter, a half-wavelength bypass type balance-unbalance converter, and the like can be used. Also, a device combining a power distributor and a phase shifter can be used.

Further, in this embodiment, since the feeding point is set to one point (a pair) for each of the pair of electrodes 2 and 3, the substrate size is limited to about 700 mm × 300 mm. However, if the number of feeding points is increased, the width of the size is increased. It is natural that it can be expanded.
In addition, if a plurality of pairs of electrodes are installed and a plurality of the above-described power supply systems are arranged according to the number of the electrodes, it is natural that the width of the substrate size can be expanded.

Further, in the manufacture of a-Si solar cells, thin film transistors, and photosensitive drums, there is no problem in performance as long as the film thickness distribution is within ± 10%. According to the above embodiment, it is possible to obtain a remarkably good film thickness distribution as compared with the conventional apparatus and method even when a power supply frequency of 60 MHz is used.
This means that the industrial value related to productivity improvement and cost reduction in the manufacturing field of a-Si solar cells, thin film transistors, and photosensitive drums is remarkably large.

Example 4
A current introduction terminal, a plasma surface treatment apparatus (plasma CVD apparatus) and a plasma surface treatment method (plasma CVD method) provided with the current introduction terminal according to the fourth embodiment of the present invention will be described with reference to FIGS. I will explain. Moreover, FIGS. 2-4 and FIG. 6 are referred as needed.

  FIG. 10 is a schematic view showing an entire plasma surface treatment apparatus (plasma CVD apparatus) having a current introduction terminal according to the fourth embodiment of the present invention, and FIG. 11 is a first and second pulse modulation shown in FIG. FIG. 12 is an explanatory diagram showing a typical example of pulse-modulated output outputted from the system phase variable 2 output oscillator, and FIG. 12 is outputted from the first and second pulse modulation system phase variable 2 output oscillators shown in FIG. FIG. 13 is an explanatory diagram showing the intensity of two standing waves generated between a pair of electrodes in the plasma surface device shown in FIG.

  First, the configuration of a plasma surface treatment apparatus (plasma CVD apparatus) provided with a current introduction terminal according to the fourth embodiment of the present invention will be described. However, the same members as those shown in FIG. 1 to FIG.

In FIG. 10, the first and second non-grounded electrodes 2 and 3 are installed with the areas of the opposed surfaces thereof being substantially equal.
In FIG. 10, reference numeral 25a denotes a first pulse modulation type phase variable 2-output transmitter which generates a sine wave signal having an arbitrary frequency of 30 MHz to 300 MHz (VHF band), for example, 60 MHz, and the sine It is possible to arbitrarily set the phase difference between two pulse-modulated sinusoidal signals that are pulse-modulated and that are output from the two output terminals.
The two pulse-modulated sinusoidal signals are respectively expressed as follows. That is, the signals W ₁₁ and W ₁₂ output from the two output terminals 26a and 26b of the first pulse modulation type phase variable two-output transmitter 25a have an angular frequency ω, a time t, and an initial phase θ _1. , Θ ₂ ,
W ₁₁ (t) = sin (ωt + θ ₁ )
W ₁₂ (t) = sin (ωt + θ ₂ )
The phase difference between the two sine wave signals output from the two output terminals of the phase-variable two-output transmitter 25a, the pulse width Hw and the period T0 of the pulse modulation are the phase difference adjuster attached to the transmitter 25a, and Each of the pulse modulation regulators can be set to an arbitrary value.
Further, the first pulse modulation type phase-variable two-output transmitter 25a transmits a pulse-modulated synchronization signal to a second pulse modulation type phase-variable two-output transmitter 25b, which will be described later, via the synchronization signal transmission cable 24. Send.
One output of the two output terminals of the first pulse modulation type phase-variable two-output transmitter 25a is transmitted to the first coupler 28a described later, and the other output is transmitted to the second coupler 28b described later. Is done.
Reference numeral 28a denotes a first coupler which outputs one output signal of two output terminals of the first pulse modulation system phase variable 2 output transmitter 25a and a second pulse modulation system phase variable 2 output described later. The output signals of one of the two output terminals of the transmitter 25b are combined and transmitted to the first amplifier 29a described later.

Reference numeral 29a is a first amplifier that amplifies the power of the signal transmitted from the first coupler 28a. Reference numeral 30a is a coaxial cable, which transmits the output of the first amplifier 29a to a first impedance matching unit 31a described later.
Reference numeral 31a is a first impedance matching unit, and the output of the first amplifier 29a is efficiently transmitted to the plasma generated between a pair of electrodes 2 and 3 described later. The impedance and the impedance of the plasma generated between the pair of electrodes 2 and 3 that are the load are matched and adjusted.
Reference numeral 32a denotes a first coaxial cable, and the output of the first amplifier 29a is supplied to the first and third feeding points 20a via the balun 33a, the current introduction terminal 40, and the connection conductors 72a and 73a. , 21a.
The first and third feeding points 20a and 21a are installed at positions facing the second and fourth feeding points 20b and 21b, which will be described later, in the power propagation direction. That is, the first and third feeding points 20a and 21a are provided on one side of the two opposing sides of the pair of electrodes 2 and 3, and the second and fourth feeding points 20b and 21b are provided on the other side. Is installed.

Reference numeral 40 denotes a current introduction terminal. Here, 40b used in the second embodiment is used. Note that the first and second connection conductors 72a and 73a shown in FIG. 6 are used for connection between the current introduction terminal 40 and the power supply points 20a and 21a disposed on the first and second electrodes.
The current introduction terminal 40 of the first amplifier 29a transmitted through the impedance matching device 31a and the balance-unbalance conversion device 33a in the plasma surface treatment apparatus (plasma CVD apparatus) having the current introduction terminal shown in FIG. When the output is supplied to the first and second electrodes 2 and 3, it is used to connect the balance-unbalance conversion device 33 a and the first and second electrodes 2 and 3. At that time, maintaining the phase difference between the two output voltages of the balance-unbalance conversion device 33a at 180 ° and supplying it to the first and second electrodes 2 and 3 is extremely important for preventing abnormal discharge. .
Therefore, in FIG. 10, it is extremely important to confirm that the voltage phase difference between the two outputs of the balance-unbalance conversion device 33a is 180 ° using a voltage phase difference measuring device (not shown).
The characteristics of the current introduction terminal 40 as a transmission circuit are as follows. That is, in FIG. 10, the atmosphere-side flange 65 of the current introduction terminal 40 is connected to the earth shield box 66 of the balance-unbalance conversion device 33a, and the power radiated from the electric circuit components inside the balance-unbalance conversion device 33a and The power radiated from the first and second rectangular plate conductors 61 and 62 of the current introduction terminal 40 is shielded. Connecting the flange 65 and the flange 68 of the earth shield box 66 is extremely important in preventing the power radiation.

Here, the function of the first amplifier 29a will be supplementarily described.
The first amplifier 29a is provided with an output value (traveling wave) monitor (not shown) and a reflected wave monitor reflected from the downstream side and returned. In addition, an isolator for protecting the electric circuit of the main body of the first power amplifier 29a by the reflected wave is attached.
For adjusting the output of the first amplifier 29a, first, for example, an output of about 20 to 30% of the maximum output of the first amplifier 29a is supplied to the first impedance matching unit 31a, the first coaxial cable 32a, and the balance / unbalance. The voltage is supplied to the first and second electrodes 2 and 3 via the conversion device 33a, the first current introduction terminal 40, and the first and second connection conductors 72a and 73a.
Next, the reactance (L and C) of the first matching unit 31a is adjusted while observing the detector of the traveling wave Pf and the reflected wave Pr attached to the first amplifier 29a. While adjusting the reactance (L and C) of the first impedance matching unit 31a, a condition is selected in which the reflected wave Pr becomes the minimum value. Then, the output of the first amplifier 29a is set to a required value, and the reflected wave Pr becomes the minimum value while adjusting the reactance (L and C) of the first matching unit 31a again with the output. Select conditions.
The adjustment of the impedance matching unit, that is, the condition that the reflected wave Pr becomes the minimum value does not change unless the plasma generation condition is changed, and therefore does not require much time.

Reference numeral 25b is a second pulse modulation type phase variable 2-output transmitter that generates a sine wave signal having an arbitrary frequency of 30 MHz to 300 MHz (VHF band), for example, 60 MHz, and pulses the sine wave signal. It is possible to arbitrarily set the phase difference between the two pulse-modulated sinusoidal signals that are modulated and output from the two output terminals.
The two pulse-modulated sinusoidal signals are respectively expressed as follows. That is, the signals W ₂₁ and W ₂₂ output from the two output terminals 27a and 27b of the transmitter 25b having the second pulse modulation system variable phase 2 output have an angular frequency ω, a time t, and an initial phase α _1. , Α ₂
W ₂₁ (t) = sin (ωt + α ₁ )
W ₂₂ (t) = sin (ωt + α ₂ )
The phase difference between the two sine wave signals output from the two output terminals of the phase variable two-output transmitter 25b, the pulse width Hw and the period T0 of the pulse modulation are the phase difference adjuster attached to the transmitter 25b, and Each of the pulse modulation regulators can be set to an arbitrary value.
The second pulse modulation system variable phase 2 output transmitter 25b transmits the pulse modulation synchronization signal transmitted from the first pulse modulation system variable phase 2 output transmitter 25a to the synchronization signal transmission cable 24. And a signal synchronized with the signal can be generated.
One output of two output terminals of the second pulse modulation type phase-variable two-output transmitter 25b is transmitted to the first coupler 28a, and the other output is transmitted to the second coupler 28b described later. .
Reference numeral 28b denotes a second coupler, which is an output signal of one of the two output terminals of the second pulse modulation system phase variable 2-output transmitter 25b and the first pulse modulation system phase variable 2-output transmitter. The output signals of one of the two output terminals 25a are combined and transmitted to a second amplifier 29b described later.

Reference numeral 29b is a second amplifier that amplifies the power of the signal transmitted from the second coupler 28b. Reference numeral 30b is a coaxial cable, which transmits the output of the second amplifier 29b to a second matching unit 31b described later.
Reference numeral 31b is a second impedance matching unit, and the output impedance of the second amplifier 29b is set so that the output of the second amplifier 29b is efficiently transmitted to the plasma generated between the pair of electrodes 2 and 3. The impedance adjustment of the plasma generated between the pair of electrodes 2 and 3 as the load is adjusted.
Reference numeral 32b is a second coaxial cable, and the output of the second amplifier 29b is supplied to the second and third feeding points 20b through the balance-unbalance conversion device 33b, the current introduction terminal 40, and the connection conductors 72a and 73a. , 21b.

Reference numeral 40 denotes a current introduction terminal. Here, 40b used in the second embodiment is used. Note that the first and second connection conductors 72a and 73a shown in FIG. 6 are used for the connection between the current introduction terminal 40 and the power supply points 20b and 21b disposed on the first and second electrodes.
The current introduction terminal 40 of the second amplifier 29b transmitted through the impedance matching device 31b and the balance-unbalance conversion device 33b in the plasma surface treatment apparatus (plasma CVD apparatus) having the current introduction terminal shown in FIG. When the output is supplied to the first and second electrodes 2 and 3, it is used to connect the balance-unbalance conversion device 33 b to the first and second electrodes 2 and 3. At that time, maintaining the phase difference between the two output voltages of the balance-unbalance conversion device 33b at 180 ° and supplying it to the first and second electrodes 2 and 3 is extremely important for preventing abnormal discharge. .
Therefore, in FIG. 10, it is extremely important to confirm that the voltage phase difference between the two outputs of the balance-unbalance conversion device 33a is 180 ° using a voltage phase difference measuring device (not shown).
The characteristics of the current introduction terminal 40 as a transmission circuit are as follows. That is, in FIG. 10, the flange 65 on the atmosphere side of the current introduction terminal 40 and the earth shield box 66 of the balance-unbalance conversion device 33b are connected, and the power radiated from the electric circuit components inside the balance-unbalance conversion device 33a and The power radiated from the first and second rectangular plate conductors 61 and 62 of the current introduction terminal 40 is shielded. Connecting the flange 65 and the flange 68 of the earth shield box 66 is extremely important in preventing the power radiation.

Here, the function of the second amplifier 29b will be supplementarily described.
Similarly to the first amplifier 29a, the second amplifier 29b is accompanied by a monitor of an output value (traveling wave) (not shown) and a monitor of a reflected wave reflected and returned from the downstream side. In addition, an isolator for protecting the electric circuit of the second power amplifier 29b main body by the reflected wave is attached.
The monitor of the output value (traveling wave) and the reflected wave reflected from the downstream side are the same as in the case of the first amplifier 29a.
The method of adjusting the output of the second amplifier 29b is the same as that of the first amplifier 29a.
The second and fourth feeding points 20b and 21b are installed at positions facing the first and third feeding points 20a and 21a, respectively, in the power propagation direction. That is, the first and third feeding points 20a and 21a are provided on one side of the two opposing sides of the pair of electrodes 2 and 3, and the second and fourth feeding points 20b and 21b are provided on the other side. Is installed.

Here, for convenience of explanation, one of the two outputs of the first pulse modulation type phase-variable two-output transmitter 25a, that is, the output signal of the output terminal 26a is the first coupler 28a and the first amplifier 29a. , The coaxial cable 30a, the first impedance matching unit 31a, the first coaxial cable 32a, the balance-unbalance conversion device 33a, the current introduction terminal 40, and the connection conductors 72a and 73a. The power transmitted to the third feeding point 21a is referred to as first power.
Similarly, one of the two outputs of the first pulse modulation system variable phase two-output transmitter 25a, that is, the output signal of the output terminal 26b is the second coupler 28b, the second amplifier 29b, the coaxial cable. 30b, the second impedance matching unit 31b, the second coaxial cable 32b, the balance-unbalance conversion device 33b, the current introduction terminal 40, the connection conductors 72a and 73a, and the second feeding point 20b and the fourth feeding. The power transmitted to the point 21b is referred to as second power.
Also, one of the two outputs of the second pulse modulation system variable phase output 2 output transmitter 25b, that is, the output signal of the output terminal 27a, is the first coupler 28a, the first amplifier 29a, the coaxial cable 30a, the first output. The first feeding point 20a and the third through the impedance matching unit 31a, the first coaxial cable 32a, the balance-unbalance conversion device 33a, the current introduction terminal 40, and the connection conductors 72a and 73a. The power transmitted to the feeding point 21a is referred to as third power.
Also, one of the two outputs of the second pulse modulation system variable phase output 2 transmitter 25b, that is, the output signal of the output terminal 27b is the second coupler 28b, the second amplifier 29b, the coaxial cable 30b, The second feeding point 20b and the fourth feeding point 21b through the second impedance matching unit 31b, the second coaxial cable 32b, the balance-unbalance conversion device 33b, the current introduction terminal 40, and the connection conductors 72a and 73a. The transmitted power is referred to as fourth power.

Here, the concept will be described with reference to FIGS. 11 and 12 in order to clarify the temporal relationship between the first, second, third and fourth powers. In FIG. 11, the horizontal axis represents time t, and the vertical axis represents power. In FIG. 12, the horizontal axis represents time t, and the vertical axis represents voltage.
Pulse-modulated first power supplied between the first and third feeding points 20a and 21a, and pulse-modulated second power supplied between the second and fourth feeding points 20b and 21b A typical example is shown in FIGS. 11 and 12 as W11 (t) and W12 (t), respectively. These two electric powers are sine waves pulse-modulated with a pulse width Hw and a period T0.
Pulse-modulated third power supplied between the first and third feeding points 20a, 21a and pulse-modulated fourth power supplied between the second and fourth feeding points 20b, 21b A typical example is shown by W21 (t) and W22 (t) in FIGS. 11 and 12, respectively. These two power waves are pulse-modulated with a pulse width Hw, a period T0, and rising at a time that is half a period later than the pulse rise time of the pulse modulation of W11 (t) and W12 (t), ie, T0 / 2. Sine wave.

Next, a method of forming amorphous Si for an a-Si solar cell using the high-frequency plasma generator configured as described above and a plasma surface treatment apparatus (plasma CVD apparatus) configured by the high-frequency plasma generator will be described.
In the implementation or application of the present invention, the first and second preliminary film forming steps and the main film forming step are necessary as procedures. In order to grasp the set value of the phase difference between the two outputs of the first pulse modulation type phase-variable two-output transmitter 25a, the first preliminary film-forming step includes In order to grasp the set value of the phase difference between the two outputs of the transmitter 25b of the second pulse modulation type phase variable and two outputs, this film forming process is performed for the purpose of manufacturing the target amorphous Si.

First, in the first first preliminary film forming step, in FIG. 10, the substrate 11 is previously set on the second electrode 3, a vacuum pump (not shown) is operated, and impurities in the vacuum container 1 are operated. After removing the gas and the like, the substrate temperature is maintained in the range of 80 to 350 ° C., for example, 180 ° C. while supplying SiH 4 gas from the discharge gas supply tube 8 at, for example, 250 sccm and a pressure of 0.5 Torr (66.5 Pa). .
Next, the first pulse modulation type phase-variable two-output transmitter 25a, the first power amplifier 29a, the first impedance matching unit 31a, the balance-unbalance conversion device 33a, the current introduction terminal 40, and the connection conductor 70a. , 71a, high-frequency power is applied to the first and second feeding points 20a, 21a of the pair of electrodes 2, 3, for example, a frequency of 60 MHz, a pulse width Hw = 400 μsec, a pulse period T0 = 1 msec of power, for example, 200 W in total is supplied.
That is, the phase difference between the two outputs of the first pulse modulation system variable phase two-output transmitter 25a is set to, for example, zero, the pulse width Hw = 400 μsec, and the pulse period T0 = 1 msec. The output of the power amplifier 29a is set to 100 W, and the output is supplied to the first and third output terminals via the first impedance matching device 31a, the balance-unbalance conversion device 33a, the current introduction terminal 40, and the connection conductors 70a and 71a. And the output of the second power amplifier 29b is set to 100 W, and the output is connected to the second impedance matching device 31b, the balance-unbalance conversion device 33b, the current introduction terminal 40, and the connection. The electric power is supplied to the second and fourth feeding points 20b and 21b via the conductors 70a and 71a.
In this case, by adjusting the first impedance matching unit 31a and the second impedance matching unit 31b, the reflected wave of the supplied power hardly returns to the upstream side of the impedance matching units 31a and 31b. be able to.

When power is supplied to the feeding points 20 a and 21 a and the feeding points 20 b and 21 b at both ends of the first and second electrodes 2 and 3, SiH 4 gas plasma is generated between the pair of electrodes 2 and 3. In this plasma generation, the pair of electrodes 2 and 3 have substantially the same area and are not grounded, and the voltage phase difference is 180 at each of the feeding points 20a and 21a and the feeding points 20b and 21b. Since the different powers, that is, the powers of the forward and return currents having the same amplitude and the phases different by 180 ° are supplied, the abnormal discharge in the vicinity of the feeding point is completely suppressed. The generated plasma is only between the pair of electrodes 2 and 3.
The reason why plasma is generated except between the pair of electrodes 2 and 3 is that the power transmission circuit supplied to the electrodes is leaked due to the unbalanced transmission circuit and one of the pair of electrodes is grounded. Leakage current generated by
In addition, the main cause of abnormal discharge in the vicinity of the feeding points 20 and 21 is that the power transmission circuit supplied to the electrodes is leaked due to the unbalanced transmission circuit and one of the pair of electrodes is grounded. The leakage current generated by
As a result, plasma of SiH 4 gas without abnormal discharge is generated between the pair of electrodes 2 and 3, and amorphous Si, for example, is deposited on the substrate 11.

In the above manner, an amorphous Si film is formed on the substrate 11 with a film formation time of, for example, 10 to 20 minutes. After film formation, the substrate 11 is taken out from the vacuum vessel 1 and the film thickness distribution of the amorphous Si film is evaluated. The film thickness distribution of, for example, amorphous Si deposited on the substrate 11 becomes a sinusoidal distribution due to the generation of a standing wave that is a phenomenon unique to the VHF plasma described above. Such a film-forming test is repeatedly performed using the phase difference between the two outputs of the first pulse modulation type phase-variable two-output transmitter 25a as a parameter. Then, in the length direction of the first electrode 2, the distance from the center point of the substrate 11 to the position of the maximum thickness of the sine film thickness distribution and the transmitter 25a of the first pulse modulation type phase variable 2 output The relationship between the phase differences between the two outputs is grasped as data.
For example, it is understood that the phase difference for setting a position that is one-eighth of the wavelength λ from the center point of the substrate 11 in the direction of the first feeding point 21, that is, λ / 8, is Δθ1, for example. Is done.
The method of grasping the relationship between the maximum position of the sinusoidal thickness distribution and the phase difference between the output voltages of the first phase variable and two-output transmitter 25a is performed by measuring the thickness distribution of the film. The method is not limited to the application method. For example, the spatial distribution in the electromagnetic wave propagation direction of the emission intensity of the generated plasma is measured with an optical sensor, and the relationship between the position of the maximum intensity and the phase difference is grasped. Also good.
However, the wavelength λ is not the wavelength of the electromagnetic wave in vacuum, but the wavelength λ in the above film forming conditions, and is shorter than the wavelength λ ₀ of the electromagnetic wave in vacuum. In general, in the plasma of SiH 4 gas, the ratio λ / λ ₀ between the wavelength λ in plasma and the wavelength λ _{0 in} vacuum is about 0.5 to 0.7.
In the case of silane gas plasma, the ratio of the wavelength λ to the wavelength λ ₀ , that is, λ / λ _0, is a pressure of about 40 to 530 Pa (0.3 to 4 Torr) and a plasma density of about 4 to 6 × 10 ⁹ / cm ³ and λ / λ ₀ = approximately 0.6. When the pressure is 530 to 1333 Pa (4 to 10 Torr), the plasma density is about 6 to 10 × 10 ⁹ / cm ³ and λ / λ ₀ = about 0.5 to 0.55.

By the way, a voltage wave of power supplied in a pulse form from the first and third feed points 20a, 21a, and a voltage wave of power supplied in a pulse form from the second and fourth feed points 20b, 21b. Are supplied from the same power source and propagate between the electrodes. That is, two electromagnetic waves having an electric field in the same direction as the normal direction of the surface of the substrate 11 are generated between the first electrode 2 and the second electrode 3, and both propagate from directions facing each other. Since they overlap, an interference phenomenon occurs. That is, a standing wave is generated.
Here, the standing wave generated by the first power and the second power is referred to as a first standing wave.

Below, the control method of the 1st standing wave is demonstrated.
In FIG. 10, the distance in the direction from the first feeding point 20a to the second feeding point 20b is x, the voltage wave propagating in the positive direction of x is W11 (x, t), and the voltage propagating in the negative direction of x. Assuming that a wave, that is, a voltage wave propagating from the second feeding point 20b to the first feeding point 20a is W21 (x, t), it is expressed as follows.
W11 (x, t) = V1 · sin (ωt + 2πx / λ)
W12 (x, t) = V1 · sin {ωt−2π (x−L0) / λ + Δθ}
Where V1 is the amplitude of the voltage wave, ω is the angular frequency of the voltage, λ is the wavelength of the voltage wave, t is time, L0 is the interval between the first and second feeding points, and Δθ is supplied from the first feeding point 20a. The phase difference between the voltage wave of the electric power and the voltage wave of the electric power supplied from the second feeding point 20b. A composite wave W1 (x, t) of these two voltage waves is expressed by the following equation.
W1 (x, t) = W11 (x, t) + W12 (x, t)
= 2 · V1cos {2π (x−L0 / 2) / λ−Δθ / 2} · sin {ωt + (πL0 / λ + Δθ / 2)
In this case, the first and second power supply systems are used to supply power between the first and third power supply points 20a and 21a and between the second and fourth power supply points 20b and 21b. The voltage waves of the power to be referred to as W11 (x, t) and W12 (x, t), respectively. Further, the combined wave of the two voltage waves is referred to as a first standing wave W1 (x, t).

By the way, the strength of the electric power between the pair of electrodes is proportional to the square of the amplitude value of the first standing wave W1 (x, t) of the voltage. That is, the power intensity I1 (x, t) is
I1 (x, t) ∝cos ² {2π (x−L0 / 2) / λ−Δθ / 2}
It is expressed.
The above equation means that a standing wave having a period of half the wavelength in the x direction is generated. Here, this is called a first standing wave. FIG. 13 conceptually shows the intensity distribution with a solid line.
Note that FIG. 13 shows that, in the generation of VHF plasma, the plasma between the pair of electrodes is uniform due to the standing wave generated by the interference between the traveling wave from the feeding point and the reflected wave from the opposite end of the feeding point. It shows the reason for the difficulty of not being. For example, if the power intensity I1 (x, t) is in the range of 0.9 to 1.0, the uniformity of the plasma is in the range of -0.05 to + 0.05λ in terms of the distance in the power propagation direction ( That is, the range in which the film thickness is uniform is limited to a length of 0.1λ).
However, the wavelength λ is not the wavelength of the electromagnetic wave in vacuum, but the wavelength λ in the above film forming conditions, and is shorter than the wavelength λ ₀ of the electromagnetic wave in vacuum. In general, in the plasma of SiH 4 gas, the ratio λ / λ ₀ between the wavelength λ in plasma and the wavelength λ _{0 in} vacuum is about 0.5 to 0.9.

Next, in the second preliminary film forming step, in FIG. 10, the substrate 11 is previously set on the second electrode 3, a vacuum pump (not shown) is operated, the impurity gas in the vacuum vessel 1, etc. Then, while the SiH 4 gas is supplied from the discharge gas supply tube 8 at, for example, 250 sccm and the pressure of 0.5 Torr (66.5 Pa), the substrate temperature is maintained in the range of 80 to 350 ° C., for example, 180 ° C.
Then, the third and fourth powers are supplied to the pair of electrodes 2 and 3 from the first and third power supply points 20a and 21a and the second and fourth power supply points 20b and 21b, respectively. For example, a frequency of 60 MHz, a pulse width Hw = 400 μs, and a pulse period T0 = 1 msec.
That is, the phase difference between the two outputs of the first pulse modulation system variable phase 2 output transmitter 25b is set to, for example, zero, the pulse width Hw = 400 μsec, and the pulse period T0 = 1 msec. The output of the power amplifier 29a is set to 100 W, and the output is supplied to the first and second output terminals via the first impedance matching device 31a, the balance / unbalance conversion device 33a, the current introduction terminal 40, and the connection conductors 70a and 71a. And the output of the second power amplifier 29b is set to 100 W, and the output is connected to the second impedance matching device 31b, the balance-unbalance conversion device 33b, the current introduction terminal 40, and the connection. The electric power is supplied to the second and fourth feeding points 20b and 21b via the conductors 70a and 71a.
In this case, by adjusting the first impedance matching unit 31a and the second impedance matching unit 31b, the reflected wave of the supplied power can be prevented from returning to the upstream side of the respective impedance matching units 31a and 31b.

When electric power is supplied from both ends of the first and second electrodes 2 and 3 to the electrodes 2 and 3, plasma of SiH 4 gas is generated between the pair of electrodes 2 and 3. In this plasma generation, the pair of electrodes 2 and 3 have substantially the same area and are not grounded, and the feeding points 20a and 21a at both ends of the first and second electrodes 2 and 3 and the feeding The points 20b and 21b are each supplied with power having a voltage phase difference of 180 °, that is, power having the same amplitude in the forward and return currents and a phase difference of 180 °. Abnormal discharge is completely suppressed. The generated plasma is only between the pair of electrodes 2 and 3.
The reason why plasma is generated except between the pair of electrodes 2 and 3 is that the power transmission circuit supplied to the electrodes is leaked due to the unbalanced transmission circuit and one of the pair of electrodes is grounded. Leakage current generated by
Also, the main cause of abnormal discharge in the vicinity of the feeding point is caused by the leakage current caused by the unbalanced transmission circuit in the power transmission circuit supplied to the electrode and one of the pair of electrodes being grounded. Leakage current.
As a result, plasma of SiH 4 gas without abnormal discharge is generated between the pair of electrodes 2 and 3, and amorphous Si, for example, is deposited on the substrate 11.

In the above manner, an amorphous Si film is formed on the substrate 11 with a film formation time of, for example, 10 to 20 minutes. After film formation, the substrate 11 is taken out from the vacuum vessel 1 and the film thickness distribution of the amorphous Si film is evaluated. The film thickness distribution of, for example, amorphous Si deposited on the substrate 11 has a sinusoidal distribution due to the generation of a standing wave that is a phenomenon inherent to the VHF plasma. Such a film forming test is repeatedly performed using the phase difference between the two outputs of the transmitter 25b of the second pulse modulation type variable phase output 2 output as a parameter. Then, in the length direction of the first electrode 2, the distance from the center point of the substrate to the position of the maximum thickness of the sinusoidal film thickness distribution and 2 of the transmitter 25 b of the second pulse modulation system variable phase 2 output. The relationship between the phase differences of the two outputs is grasped as data.
Also in this case, similarly to the first preliminary film forming step, in the case where the third and fourth power supply systems are used, the distance from the center point of the substrate to the position of the maximum thickness of the sinusoidal film thickness distribution. And the position of the maximum thickness of the film thickness distribution, for example, from the center point of the substrate by the data indicating the relationship between the phase differences between the two outputs of the transmitter 25b of the second pulse modulation type phase variable and two outputs. It can be understood that the phase difference for setting the position in the direction of the point 27 to one-eighth of the wavelength λ, that is, a position separated by λ / 8 is, for example, Δθ2.
The method of grasping the relationship between the maximum position of the sinusoidal thickness distribution and the phase difference between the output voltages of the first phase variable and two-output transmitter 25a is performed by measuring the thickness distribution of the film. The method is not limited to the application method. For example, the spatial distribution in the electromagnetic wave propagation direction of the emission intensity of the generated plasma is measured with an optical sensor, and the relationship between the position of the maximum intensity and the phase difference is grasped. Also good.
However, the wavelength λ is not the wavelength of the electromagnetic wave in vacuum, but the wavelength λ in the above film forming conditions, and is shorter than the wavelength λ ₀ of the electromagnetic wave in vacuum. In general, in the plasma of SiH 4 gas, the ratio λ / λ ₀ between the wavelength λ in plasma and the wavelength λ _{0 in} vacuum is about 0.5 to 0.9.
In the case of silane gas plasma, the ratio of the wavelength λ to the wavelength λ ₀ , that is, λ / λ _0, is a pressure of about 40 to 530 Pa (0.3 to 4 Torr) and a plasma density of about 4 to 6 × 10 ⁹ / cm ³ and λ / λ ₀ = approximately 0.6. When the pressure is 530 to 1333 Pa (4 to 10 Torr), the plasma density is about 6 to 10 × 10 ⁹ / cm ³ and λ / λ ₀ = about 0.5 to 0.55.

In the second preliminary film-forming step, the two power voltage waves supplied from the first and second feeding points 20a and 21a and the second and fourth feeding points 20b and 21b are oscillated from the same power source. Propagating between the electrodes. That is, two electromagnetic waves having an electric field in the same direction as the normal direction of the surface of the substrate 11 are generated between the first electrode 2 and the second electrode 3, and both propagate from directions facing each other. Since they overlap, an interference phenomenon occurs. That is, a standing wave is generated. Here, this is referred to as a second standing wave.
In FIG. 10, the distance in the direction from the first feeding point 20a to the second feeding point 20b is x, the voltage wave propagating in the positive direction of x is W21 (x, t), and the voltage propagating in the negative direction of x. Assuming that a wave, that is, a voltage wave propagating from the second feeding point 20b to the first feeding point 20a is W22 (x, t), it is expressed as follows.
W21 (x, t) = V2 · sin (ωt + 2πx / λ)
W22 (x, t) = V2 · sin {ωt−2π (x−L0) / λ + Δθ}
Where V2 is the amplitude of the voltage wave, ω is the angular frequency of the voltage, λ is the wavelength of the voltage wave, t is the time, L0 is the interval between the first and second feed points, and Δθ is supplied from the first feed point 20a. The phase difference between the voltage wave of the electric power and the voltage wave of the electric power supplied from the second feeding point 20b. The voltage composite wave W2 (x, t) is expressed by the following equation.
W2 (x, t) = W21 (x, t) + W22 (x, t)
= 2 · V2cos {2π (x−L0 / 2) / λ−Δθ / 2} · sin {ωt + (πL0 / λ + Δθ / 2)
Here, the third and fourth power supply systems are used to supply power between the first and third feeding points 20a and 21a and between the second and fourth feeding points 20b and 21b. The voltage waves of the power to be referred to as W21 (x, t) and W22 (x, t), respectively. The combined wave of the two voltage waves is called a second standing wave W2 (x, t).

By the way, the strength of the power between the pair of electrodes is proportional to the square of the amplitude value of the combined wave W2 (x, t) of the voltage. That is, the power intensity I2 (x, t) is
I2 (x, t) ∝cos ² {2π (x−L0 / 2) / λ−Δθ / 2}
It is expressed.
The above equation means that a standing wave having a period of half the wavelength in the x direction is generated. Here, this is referred to as a second standing wave.

Now, in response to the results of the first and second preliminary film forming steps, the main film forming step is started. First, in FIG. 10, the substrate 11 is previously set on the second electrode 4, a vacuum pump (not shown) is operated to remove impurity gas in the vacuum vessel 1, and then SiH 4 is discharged from the discharge gas supply pipe 8. While the gas is supplied at, for example, 300 sccm and the pressure of 0.5 Torr (66.5 Pa), the substrate temperature is maintained in the range of 80 to 350 ° C., for example, 180 ° C.
Next, the phase difference between the voltages of the two outputs of the first pulse modulation type phase-variable two-output transmitter 25a of the components of the power supply system of the first and second electric powers is determined as a first preliminary film forming step. Is set as Δθ1 grasped as the data, and pulse width Hw and period T0 in W11 (t) and W12 (t) shown in FIG. 13 are set to Hw = 400 μsec and T0 = 1 msec, for example. For example, electric power of 500 W is supplied between feeding points at both ends of the first and second electrodes, and the second pulse modulation system phase variable of the constituent members of the third and fourth electric power supply systems is provided. The phase difference between the voltages of the two outputs of the two-output transmitter 25b is set to Δθ2 grasped as data of the second preliminary film-forming process, and the pulse modulation thereof is shown by W21 (t) and W22 ( pulse width Hw at t) Further, the period T0 is set to, for example, Hw = 400 μsec and T0 = 1 msec, and rises at a half cycle, that is, a time delayed by T0 / 2 from the pulse rise time of the pulse modulation of W11 (t) and W12 (t). For example, electric power of 500 W is supplied between feeding points at both ends of the first and second electrodes.
That is, the voltage waves W11 (x, t), W12 (x, t), W21 (x, t) and W22 (x, t) are supplied to the feeding points at both ends of the first and second electrodes. The
Here, the first pulse modulation system variable phase 2 output transmitter 25a and the second pulse modulation system variable phase 2 output transmitter set in the first preliminary film forming process and the second preliminary film forming process, respectively. By changing the value of the pulse width Hw and the period T0 of 25b to, for example, Hw = 400 μsec to 1 msec or the like, and T0 = 1 msec to 5 msec or the like, some film forming data can be compared.

When four voltage waves are supplied from both ends of the pair of electrodes 2 and 3, W11 (x, t) and W12 (x, t) interfere to form the first standing wave W1 (x, t). W21 (x, t) and W22 (x, t) interfere to form a second standing wave W2 (x, t).
However, W11 (x, t) does not interfere with W21 (x, t) and W22 (x, t) because they are temporally separated. Similarly, W12 (x, t) does not interfere with W21 (x, t) and W22 (x, t).
Therefore, considering a general film formation time of several seconds or longer, which is significantly longer than the pulse modulation period T0, the distribution of the intensity of power generated between the pair of electrodes 2 and 3 is the first standing wave. The intensity distribution I1 (x, t) of W1 (x, t) and the intensity distribution I2 (x, t) of the second standing wave W2 (x, t) are superimposed. The state is conceptually shown in FIG. 13 with the first standing wave as a solid line and the second standing wave as a dotted line.
Here, if the center point of the substrate is the origin of the x-axis and the direction from the origin toward the first feeding point 21 is a positive direction, the strength of the first standing wave W1 (x, t) Distribution I1 (x, t) is
I1 (x, t) ∝cos ² {2πx / λ + 2π (λ / 8) / λ}
= Cos ² {2πx / λ + π / 4}
The intensity distribution I2 (x, t) of the second standing wave W2 (x, t) is
I2 (x, t) ∝cos ² {2πx / λ-2π (λ / 8) / λ}
= Cos ² {2πx / λ−π / 4}
The distribution I (x, t) of the strength of power generated between the pair of electrodes 2 and 4 is
I (x, t)
= Cos ² {2πx / λ + π / 4} + cos ² {2πx / λ−π / 4}
= 1
That is, it can be rewritten as follows.
I (x)
= Cos ² {2πx / λ} + sin ² {2πx / λ}
= 1
The general expression is as follows.
I (x) = cos ² (2πx / λ + Δθ / 2) + sin ² (2πx / λ + Δθ / 2)
Where x is the distance in the propagation direction of the supplied power, λ is the wavelength when the used power is propagated in the plasma, and Δθ is the initial phase difference of the voltages at the two feeding points arranged at both ends of the pair of electrodes.
The above matter means that the power intensity distribution between the pair of electrodes is uniform without depending on the wavelength λ of the power used. That is, in the field of application to plasma surface treatment in which the power intensity between a pair of electrodes and the plasma intensity are in a proportional relationship, it is possible to generate a uniform plasma between the pair of electrodes. means.

As a result, uniform SiH 4 plasma is generated between the pair of electrodes 2 and 3, and, for example, amorphous Si is deposited on the substrate 11. In general, it is known that the strength of plasma generated between a pair of electrodes used in the field of plasma surface treatment is proportional to the strength of power between the pair of electrodes.
In this case, in addition to the power distribution between the pair of electrodes 2 and 3 being uniform, in the plasma generation, the pair of electrodes 2 and 3 have substantially the same area and are not grounded. In addition, power having a voltage phase difference of 180 ° is supplied to the feeding points at both ends of the electrode, that is, power having the same amplitude in the forward and return currents and a phase of 180 ° different from each other. Abnormal discharge in the vicinity of the feeding point is completely suppressed. The generated plasma is only between the pair of electrodes 2 and 3.
The reason why plasma is generated except between the pair of electrodes 2 and 3 is that the power transmission circuit supplied to the electrodes is leaked due to the unbalanced transmission circuit and one of the pair of electrodes is grounded. Leakage current generated by
In addition, the main cause of abnormal discharge in the vicinity of the feeding points 20a, 20b, 21a, and 21b is that the power transmission circuit supplied to the electrodes has a leakage current caused by an unbalanced transmission circuit and one of the pair of electrodes. This is a leakage current generated by grounding.
As a result, abnormal discharge in the vicinity of the feeding point is suppressed, and plasma having a uniform intensity according to a uniform power distribution is generated.

The above results indicate that high-frequency plasma generation used in a surface treatment apparatus for processing the surface of a substrate placed in a vacuum vessel using plasma generated using the power of an output of a high-frequency power source whose oscillation frequency belongs to the VHF band. In the apparatus, a first standing wave and a second standing wave having different antinode positions of standing waves of electromagnetic waves having an electric field in the same direction as a normal direction of the surface of the substrate are generated, and the first By providing the means for superimposing the first and second standing waves, it is meaningful that the distribution of the power intensity between the electrodes, which is indispensable for the uniformity of the plasma, can be controlled.
Further, if the distance between the antinodes of the first and second standing waves is 0.25 times the wavelength λ in the plasma of the electromagnetic wave used, that is, 0.25λ, a pair of electrodes The power intensity distribution I (x, t) generated between 2 and 4 has a constant value and does not depend on the position in the power propagation direction, and is uniform.
In the above embodiment, the leakage current caused by the unbalanced transmission circuit is caused by the transmission circuit of power supplied to the electrode that is the main cause of the abnormal discharge in the vicinity of the feeding points 20a, 20b, 21a, and 21b.
The current introduction terminal 40 and the balance-unbalance conversion devices 33a and 33b can be almost completely suppressed. In the above embodiment, the pair of electrodes are non-grounded and have substantially the same area, and power is supplied through the balanced transmission line by the current introduction terminal 40 and the balanced / unbalanced converters 33a and 33b. Leakage current generated by grounding one of the pair of electrodes is almost completely suppressed.
This means that it is an epoch-making discovery in the sense that it is possible to provide a device capable of realizing large-area and uniform plasma processing, which is an important issue in the application field of VHF plasma or UHF plasma. Yes.
The distance between the antinodes of the first and second standing waves is 0.22 to 0.28 times the wavelength λ in the plasma of the electromagnetic wave used, that is, 0.22 to 0.2. If it is 28λ, the distribution I (x, t) of the intensity of power generated between the pair of electrodes 2 and 4 is ± 20% or less.
The distance between the antinodes of the first and second standing waves is 0.238 to 0.263 times the wavelength λ in the plasma of the electromagnetic wave used, that is, 0.238 to. In the case of H.263λ, the distribution I (x, t) of the intensity of power generated between the pair of electrodes 2 and 4 is ± 10% or less.

In the above process, when the SiH 4 gas is turned into plasma, radicals such as SiH 3, SiH 2, and SiH existing in the plasma diffuse due to a diffusion phenomenon and are adsorbed on the surface of the substrate 11, thereby depositing an a-Si film. However, since the power distribution between the pair of electrodes 2 and 4 is uniform in time average as described above, the deposited film becomes uniform.
This indicates that the apparatus and method of the present invention can form a uniform film thickness distribution even when a substrate having a size exceeding one half of the wavelength λ is targeted. That is, even when a substrate having a size exceeding one-half of the wavelength λ, which is impossible with the conventional VHF plasma surface treatment apparatus and method, is targeted, the present invention can realize a uniform film thickness distribution. It means that.
Therefore, the above is an epoch-making discovery in the application field of VHF plasma, and its practical value is extremely large.
It is a well-known technique that microcrystalline Si, thin-film polycrystalline Si, or the like can be formed by optimizing the flow ratio, pressure, and power of SiH4 and H2 in the film forming conditions.
In addition, it is a known technique that can be applied to etching by using NF3, SF6, CF4, CHF3, C4F4, or the like as a discharge gas.

  In this embodiment, since the size of the pair of electrodes 2 and 3 is 1800 mm × 300 m, the substrate size is limited to about 1800 mm × 300 mm. However, a plurality of pairs of electrodes are installed, and the above-described power supply is performed according to the number of the electrodes. Naturally, if a plurality of systems are arranged, the width of the substrate size can be expanded.

Further, in the manufacture of a-Si solar cells, thin film transistors, and photosensitive drums, there is no problem in performance as long as the film thickness distribution is within ± 10%. According to the above embodiment, even when a power supply frequency of 60 MHz is used, the power intensity distribution I (x, t) between the pair of electrodes 2 and 3 that is impossible with the conventional apparatus and method is uniform. Is possible. In other words, the film thickness distribution can be within ± 10%.
This means that a plasma surface treatment apparatus using a frequency in the VHF band can be provided as a means for drastic improvement in terms of productivity improvement and cost reduction in the manufacturing field of a-Si solar cells, thin film transistors, and photosensitive drums. Means. The industrial value of this effect is significantly great.

FIG. 1 is a schematic view showing an entire plasma surface treatment apparatus (plasma CVD apparatus) having a current introduction terminal according to the first embodiment of the present invention. FIG. 2 is a schematic view showing the entire current introduction terminal according to the first embodiment of the present invention. FIG. 3 is an explanatory diagram relating to a connection portion between a balance-unbalance converter, a current introduction terminal, and electrodes in the power supply system of the plasma surface treatment apparatus shown in FIG. FIG. 4 is an explanatory diagram relating to the characteristic impedance of the current introduction terminal according to the first embodiment of the present invention. FIG. 5 is a conceptual diagram showing a means for connecting a current introduction terminal and an electrode according to the second embodiment of the present invention. FIG. 6 is an explanatory view showing a first specific example of the connection means between the current introduction terminal and the electrode according to the second embodiment of the present invention. FIG. 7 is an explanatory view showing a second specific example of the connection means between the current introduction terminal and the electrode according to the second embodiment of the present invention. FIG. 8 is a conceptual diagram showing a means for connecting a current introduction terminal and an electrode according to the third embodiment of the present invention. Fig.9 (a) is explanatory drawing which shows the external appearance of the electric current introduction | transduction terminal using the rectangular tube concerning the 3rd Embodiment of this invention. FIG. 9B is an explanatory view showing the appearance of a current introduction terminal using a circular tube according to the third embodiment of the present invention. FIG. 10 is a schematic view showing an entire plasma surface treatment apparatus (plasma CVD apparatus) having a current introduction terminal according to the fourth embodiment of the present invention. FIG. 11 is an explanatory view showing a typical example of pulse-modulated output outputted from the first and second pulse modulation type variable-phase two-output transmitters shown in FIG. 12 is an explanatory view showing a typical example of a pulse-modulated sine wave signal output from the first and second pulse modulation type variable-phase two-output transmitters shown in FIG. FIG. 13 is an explanatory diagram showing the intensity of two standing waves generated between a pair of electrodes in the plasma surface apparatus shown in FIG.

Explanation of symbols

1 ... Vacuum container,
2, 3... First and second ungrounded electrodes,
4 ... Substrate heater,
5a, 5b, 5c, 5d ... insulator support material,
6 ... discharge gas mixing box,
7 ... Rectifying plate,
8: Gas supply pipe,
9: Gas ejection hole,
10a, 10b ... exhaust pipe,
11 ... substrate
20, 21 ... first and second feeding points,
25 ... high frequency power supply,
30: Coaxial cable,
31 ... impedance matching unit,
32 ... Coaxial cable,
33 ... Balance-unbalance conversion device,
40: Current introduction terminal,
60 ... tubular conductor,
61, 62 ... first and second rectangular plate conductors,
63, 64 ... first and second dielectrics,
65 ... flange,
66 ... Earth shield box of balance-unbalance conversion device 33,
68: A flange of the earth shield box 66.

Claims (17)

  A vacuum vessel provided with an exhaust system, a discharge gas supply system for supplying a discharge gas into the vacuum vessel, a pair of electrodes including first and second electrodes for generating plasma, and impedance matching with a high frequency power source A plasma surface treatment for treating the surface of the substrate using the generated plasma, comprising: a power supply system comprising a vessel, a balance-unbalance conversion device and a current introduction terminal; and a substrate holding means for arranging a substrate to be plasma-treated. In the current introduction terminal used in the apparatus, there are two rectangular plate conductors that have a tubular conductor installed on the wall of the vacuum vessel through the wall of the vacuum vessel, and are insulated from each other by a dielectric, A first rectangular plate-shaped conductor and a second rectangular plate-shaped conductor, the first rectangular plate-shaped conductor and the second rectangular plate-shaped conductor are installed inside the tubular conductor via a dielectric, And the first rectangular plate shape One end of the body and the second rectangular plate conductor in the length direction is disposed inside the vacuum vessel, that is, on the vacuum side, and the other end is disposed outside the vacuum vessel, that is, on the atmosphere side. The one end of the tubular conductor is in close contact with the ground shield box of the conductor surrounding the balance-unbalance conversion device, and the ends on the atmosphere side of the first and second rectangular plate conductors are used as the input section. A current introduction terminal having a configuration in which the vacuum side ends of the first and second rectangular plate conductors are used as output portions.   A vacuum vessel provided with an exhaust system, a discharge gas supply system for supplying a discharge gas into the vacuum vessel, a pair of electrodes composed of first and second electrodes for generating plasma, and the pair of electrodes First and second standing waves, which are independent of each other, are superimposed and generated, and the distance between the antinode position of the first standing wave and the antinode position of the second standing wave is determined as the pair. A high frequency power source, an impedance matching unit, a balance-unbalance converter, and a current set to 0.22 to 0.28 times the wavelength λ of the electromagnetic wave propagating inside the generated plasma between the electrodes of In a current introduction terminal used in a plasma surface treatment apparatus comprising a power supply system comprising an introduction terminal and a substrate holding means for arranging a substrate to be plasma treated, and processing the surface of the substrate using the generated plasma. The vacuum container passes through the wall of the vacuum vessel. Two rectangular plate conductors having a tubular conductor placed on the wall of the vessel and insulated from each other by a dielectric, that is, a first rectangular plate conductor and a second rectangular plate conductor, A first rectangular plate-shaped conductor and a second rectangular plate-shaped conductor are installed inside the tubular conductor via a dielectric, and the lengths of the first rectangular plate-shaped conductor and the second rectangular plate-shaped conductor are One end in the vertical direction is disposed inside the vacuum vessel, that is, on the vacuum side, and the other end is disposed outside the vacuum vessel, that is, on the atmosphere side, and one end of the tubular conductor and the end A conductor earth shield box surrounding the balance-unbalance conversion device is brought into close contact, and the atmosphere side ends of the first and second rectangular plate conductors are used as input portions, and the first and second rectangular plate shapes are used. A current introduction terminal having a configuration in which an end portion on a vacuum side of a conductor is used as an output portion.   3. The current introduction terminal according to claim 1, wherein a relative dielectric constant of a dielectric between the first and second rectangular plate conductors is 3 or more.   The current introduction terminal according to any one of claims 1 to 3, wherein the first rectangular plate conductor and the second rectangular plate conductor constituting the current introduction terminal are not grounded. A current introduction terminal characterized by that.   5. The current introduction terminal according to claim 1, wherein the dielectric interposed between the first rectangular plate-shaped conductor and the second rectangular plate-shaped conductor has a wedge shape. Characteristic current introduction terminal.   5. The current introduction terminal according to claim 1, wherein a characteristic impedance of the current introduction terminal has a sloped distribution in which the characteristic impedance continuously decreases along the direction from the input portion to the output portion. A current introduction terminal characterized by being.   A vacuum vessel provided with an exhaust system, a discharge gas supply system for supplying a discharge gas into the vacuum vessel, a pair of electrodes including first and second electrodes for generating plasma, and impedance matching with a high frequency power source A plasma surface treatment for treating the surface of the substrate using the generated plasma, comprising: a power supply system comprising a vessel, a balance-unbalance conversion device and a current introduction terminal; and a substrate holding means for arranging a substrate to be plasma-treated. In the balanced transmission method used in the apparatus, the areas of the opposing surfaces of the pair of electrodes are substantially equal, and the pair of electrodes are installed in an ungrounded state, and the output circuit of the balance-unbalance conversion apparatus and the pair The power supply point installed on the electrode is connected with the current introduction terminal according to any one of claims 1 to 6, and the output of the balance-unbalance conversion device is transmitted to the power supply point. When Balanced transmission method that.   A vacuum vessel provided with an exhaust system, a discharge gas supply system for supplying a discharge gas into the vacuum vessel, a pair of electrodes including first and second electrodes for generating plasma, and impedance matching with a high frequency power source A plasma surface treatment for treating the surface of the substrate using the generated plasma, comprising: a power supply system comprising a vessel, a balance-unbalance conversion device and a current introduction terminal; and a substrate holding means for arranging a substrate to be plasma-treated. In the apparatus, the areas of the opposed surfaces of the pair of electrodes are substantially equal, and the pair of electrodes are installed in an ungrounded state, and the output circuit of the balance-unbalance conversion device of the component of the power supply system and the output circuit A plasma surface treatment apparatus having a configuration in which a power supply point of a pair of electrodes is connected by the current introduction terminal according to any one of claims 1 to 6.   A vacuum vessel provided with an exhaust system, a discharge gas supply system for supplying a discharge gas into the vacuum vessel, a pair of electrodes composed of first and second electrodes for generating plasma, and the pair of electrodes First and second standing waves, which are independent of each other, are superimposed and generated, and the distance between the antinode position of the first standing wave and the antinode position of the second standing wave is determined as the pair. A high frequency power source, an impedance matching unit, a balance-unbalance converter, and a current set to 0.22 to 0.28 times the wavelength λ of the electromagnetic wave propagating inside the generated plasma between the electrodes of In a plasma surface treatment apparatus, comprising a power supply system comprising an introduction terminal and a substrate holding means for placing a substrate to be plasma treated, and treating the surface of the substrate using the generated plasma, the pair of electrodes are mutually connected The areas of the opposing faces are substantially equal, and A pair of electrodes are installed in an ungrounded state, and an output circuit of a balance-unbalance conversion device of a component of the power supply system and a power supply point of the pair of electrodes are any one of claims 1 to 6. A plasma surface treatment apparatus having a configuration in which the current introduction terminals are connected.   A vacuum vessel provided with an exhaust system, a discharge gas supply system for supplying a discharge gas into the vacuum vessel, a pair of electrodes composed of first and second electrodes for generating plasma, and the pair of electrodes A power supply system comprising a power supply point, a high-frequency power source, an impedance matching unit, a balance-unbalance conversion device, and a current introduction terminal according to any one of claims 1 to 6, and a substrate on which a substrate to be plasma-processed is arranged A plasma surface treatment apparatus that treats the surface of the substrate using the generated plasma, the apparatus configuration of the power supply circuit that supplies power from the power supply system to the pair of electrodes includes: A plasma surface treatment characterized by being arranged in the order of the high-frequency power source, the impedance matching unit, the balance-unbalance conversion device, the current introduction terminal, and the power supply point from the upstream side to the downstream side of the flow. Apparatus.   A vacuum vessel provided with an exhaust system, a discharge gas supply system for supplying a discharge gas into the vacuum vessel, a pair of electrodes composed of first and second electrodes for generating plasma, and the pair of electrodes First and second standing waves, which are independent of each other, are superimposed and generated, and the distance between the antinode position of the first standing wave and the antinode position of the second standing wave is determined as the pair. A high frequency power source, an impedance matching device, a balance-unbalance converter, and a balance-unbalance conversion device set to 0.22 to 0.28 times the wavelength λ of the electromagnetic wave propagating through the generated plasma between the electrodes A power supply system comprising the current introduction terminal according to any one of Items 1 to 6, and a substrate holding means for arranging a substrate to be plasma-processed, and processing the surface of the substrate using the generated plasma In the plasma surface treatment apparatus, the power supply system The apparatus configuration of the power supply circuit that supplies power to the pair of electrodes includes the high-frequency power source, the impedance matching unit, the balance-unbalance conversion device, the current introduction terminal, and the power supply point from the upstream side to the downstream side of the power flow. The plasma surface treatment apparatus is arranged in the order of:   The plasma surface treatment apparatus according to any one of claims 8 to 11, wherein the current introduction terminal and the power supply point are connected by a flat conductor. .   A vacuum vessel provided with an exhaust system, a discharge gas supply system for supplying a discharge gas into the vacuum vessel, a pair of electrodes composed of first and second electrodes for generating plasma, and the pair of electrodes A power supply system comprising a power supply point, a high-frequency power source, an impedance matching unit, a balance-unbalance conversion device, and a current introduction terminal having the configuration according to any one of claims 1 to 6, and a substrate to be plasma-treated And a substrate holding means for disposing the substrate, and the surface of the substrate is processed using the generated plasma. The apparatus constituting the power supply system is arranged from the upstream side to the downstream side of the power flow. The plasma surface treatment is performed by arranging the high-frequency power source, the impedance matching device, the balance-unbalance conversion device, the current introduction terminal, and the power supply point in this order. Processing method.   A vacuum vessel provided with an exhaust system, a discharge gas supply system for supplying a discharge gas into the vacuum vessel, a pair of electrodes including first and second electrodes for generating plasma, and impedance matching with a high frequency power source And a balance-unbalance conversion device, a power supply system comprising the current introduction terminal according to any one of claims 1 to 6, and a substrate holding means for arranging a substrate to be plasma-processed, and a generated plasma In the plasma surface treatment method for treating a surface of a substrate using a substrate, the areas of the opposed surfaces of the pair of electrodes are substantially equal, and the pair of electrodes are installed in a non-grounded state, and the balance-unbalance conversion is performed. The plasma surface treatment method is characterized in that the plasma surface treatment is performed by transmitting the output of the apparatus to the power supply point installed on the electrode through the current introduction terminal.   A vacuum vessel provided with an exhaust system, a discharge gas supply system for supplying a discharge gas into the vacuum vessel, a pair of electrodes composed of first and second electrodes for generating plasma, and the pair of electrodes The first and second standing waves that are independent of each other are superimposed on the power supply point and the pair of electrodes, and the antinode position of the first standing wave and the second standing wave are generated. A high frequency power source and an impedance in which the distance between the antinodes of the wave is set to 0.22 to 0.28 times the wavelength λ of the electromagnetic wave propagating through the generated plasma between the pair of electrodes, that is, 0.22 to 0.28λ. A power supply system comprising a matching unit, a balance-unbalance conversion device, a current introduction terminal having the configuration according to any one of claims 1 to 6, and a substrate holding means for arranging a substrate to be plasma-processed. Plasma surface treatment that uses the generated plasma to treat the surface of the substrate In the control method, the devices constituting the power supply system are arranged in the order of the high-frequency power source, the impedance matching unit, the balance-unbalance conversion device, the current introduction terminal, and the power supply point from the upstream side to the downstream side of the power flow. A plasma surface treatment method characterized in that plasma surface treatment is performed by disposing them.   A vacuum vessel provided with an exhaust system, a discharge gas supply system for supplying a discharge gas into the vacuum vessel, a pair of electrodes composed of first and second electrodes for generating plasma, and the pair of electrodes First and second standing waves, which are independent of each other, are superimposed and generated, and the distance between the antinode position of the first standing wave and the antinode position of the second standing wave is determined as the pair. A high frequency power source, an impedance matching device, a balance-unbalance converter, and a balance-unbalance conversion device set to 0.22 to 0.28 times the wavelength λ of the electromagnetic wave propagating through the generated plasma between the electrodes A power supply system comprising the current introduction terminal according to any one of Items 1 to 6, and a substrate holding means for arranging a substrate to be plasma-processed, and processing the surface of the substrate using the generated plasma In the plasma surface treatment method, the pair of electrodes are paired with each other. And the pair of electrodes are installed in an ungrounded state, and the output of the balance-unbalance conversion device is transmitted to the power supply point installed in the electrodes via the current introduction terminal. A plasma surface treatment method, wherein plasma surface treatment is performed.   17. The plasma surface treatment method according to claim 13, wherein a phase difference between voltages of two outputs of the balance-unbalance conversion device is set to 180 °. .

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