JPH0822960A - Plasma film forming equipment and forming method - Google Patents

Abstract

PURPOSE:To restrain the bending of a flexible board in the width direction, and improve the uniformity of film formation, by generating plasma discharge in a closed space constituted by closing both end surfaces of a cylindrical body formed by bending the flexible board, and growing a film on the inner surface of the cylindrical body. CONSTITUTION:A flexible board 1 wound around a roll 2 is made to pass slits 4 or the like via a guide roll 2, and wound up by a winding-up roll 12 via a guide roll 11. In each layer forming chamber, the flexible board 1 is wound with a disk body via a guide roll 12, and an almost cylindrical body 13 is formed. The cylindrical body 13 is made to pass the slit via a roll guide 14, and sent out to an adjacent chamber. A center electrode 15 is formed in the cylindrical body 13, and generates plasma in a gap part 16 between the electrode 15 and the cylindrical body 13 of the flexible board 1. Decomposition film formation gas is introduced into the gap part 16. From the viewpoint of uniformity, it is desirable for the decomposition film formation gas to be discharged from the center electrode 15 in the direction of the cylindrical body 13 of the flexible board 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma film forming apparatus and a plasma film forming method for forming a thin film on a surface of a substrate by decomposing a decomposition film forming gas by using plasma discharge, and more particularly to a thin film semiconductor. The present invention relates to a plasma film forming apparatus and a plasma film forming method that can be used for mass production of an apparatus.

[0002]

2. Description of the Related Art As a typical thin film semiconductor device,
There is a solar cell in which an amorphous thin film semiconductor typified by hydrogenated amorphous silicon is used as a power generation layer. This is generally formed by so-called plasma chemical vapor deposition, which decomposes a hydrogenated silicon compound gas or the like to form a thin film on the surface of a substrate using plasma discharge, and a thin film can be formed over a large area. It has the advantage that it can. The structure of the basic unit of this solar cell consists of a substantially undoped semiconductor i layer sandwiched between a semiconductor doped layer of one conductivity type and a semiconductor doped layer of the opposite conductivity type, or a pin structure or ni- The p-structure and the substantially undoped semiconductor i layer act as a light absorption power generation layer. Here, in an amorphous thin film semiconductor typified by hydrogenated amorphous silicon, even if a trace amount of a dopant such as boron or phosphorus is mixed in, the level density in the gap rapidly increases and the electrical characteristics of the film deteriorate. Therefore, it is necessary to form the semiconductor i layer while suppressing the mixture of these dopants as much as possible. Therefore, when forming an amorphous thin-film solar cell on a rigid substrate such as a glass substrate, the p-layer deposition chamber and i
The layer deposition chamber and the n-layer deposition chamber are separated by a gate valve, the supply of raw material gas is stopped after each layer is deposited, the raw material gas is evacuated, and the substrate is placed in the next evacuated deposition chamber. It has a structure of moving. However, such a batch processing method requires a discontinuation of film formation and a vacuum exhaust process of the raw material gas, which is a serious problem from the viewpoint of productivity. From the viewpoint of productivity, a continuous film formation method in which plasma discharge in each film formation chamber is continued and a long flexible substrate is continuously moved to each film formation chamber to stack each layer is preferable.
As such a plasma film forming apparatus, there is an apparatus described in Japanese Patent Publication No. 4-32533.

In this known example, a long flexible substrate is moved in a substantially straight line so as to pass through each film forming chamber. However, this structure has the following problems. First of all, there is a drawback that the device becomes long and requires a large installation area. This drawback becomes serious especially when used for manufacturing an amorphous thin film solar cell. That is, the light absorption power generation layer of the amorphous thin-film solar cell is the i layer, but in order to sufficiently absorb sunlight and obtain a high photocurrent, when the i layer is hydrogenated amorphous silicon, It is necessary to set the i-layer film thickness to 3500Å or more, and the p- and n-layers are about 100Å, which is extremely thick, and the difference in film formation speed cannot be so large. There is a problem that the room becomes large. Furthermore, in a solar cell consisting of only one p-i-n structure or n-i-p structure, if the i-layer is hydrogenated amorphous silicon, it will absorb sufficient sunlight and obtain a high photocurrent. In order to achieve this, it is necessary to make the i-layer thickness 3500Å or more.However, hydrogenated amorphous silicon semiconductor films have the property of increasing the level density in the gap due to light irradiation. However, there is a problem that this deterioration rate is particularly high, and the power generation efficiency of the solar cell is greatly decreased with time. Therefore, in a practical solar cell,
Especially, the thickness of the i layer on the light incident side is set to 1500 Å or less, and the p-i-n
It is necessary to have a structure in which two or more layers of the structure or the nip structure are laminated. However, even in the structure of two layers laminated, six deposition chambers are required. It is necessary to provide a buffer chamber for suppressing mutual mixing of dopants between the film forming chambers of the doped layers of the two power generation layers, and the continuous film forming apparatus becomes even longer. Furthermore, in order to improve the photoelectric conversion efficiency of amorphous thin-film solar cells, a structure with three layers of pin structure or nip structure is stacked, and the i layer of the power generation layer after the light incidence is made of hydrogen. It is desirable to use a narrow bandgap film made of an amorphous silicon germanium alloy,
In this case, nine film forming chambers are required and two buffer chambers are required, so that the continuous film forming apparatus becomes extremely long. Further, it is desirable that the narrow band gap i layer made of a hydrogenated amorphous silicon germanium alloy has a profile in which the composition ratio of silicon and germanium is changed, and this i layer forming chamber is further divided. Therefore, the continuous plasma film forming apparatus having the conventional configuration has a problem that the apparatus becomes extremely large and requires an extremely large apparatus installation area.

Secondly, in the above-mentioned structure of the continuous plasma film forming apparatus in which the long flexible substrate moves in a substantially straight line, the flexible substrate is easily bent in the width direction. When the flexible substrate bends in the width direction, the distance between the cathode for plasma discharge and the flexible substrate varies, which causes a problem in uniformity of film formation in the width direction. As a method of coping with this, Japanese Patent Publication No. 3-76595 discloses a method of correcting the deflection by using a flexible substrate as a magnetic body and a magnet. The flexible substrate easily bends in a wave shape in the length direction, and also causes a large resistance to the movement of the flexible substrate.

Thirdly, in the structure of the continuous plasma film forming apparatus in which the long flexible substrate moves in a substantially straight line, the dopant gas is easily mixed in the i layer film forming chamber, There is a drawback in that a dopant is easily mixed in the i-layer and the film quality of the i-layer is deteriorated. With a configuration in which a long flexible substrate is continuously moved while continuing plasma film formation, it is difficult to completely separate the film formation chambers, and it is necessary to connect each film formation chamber through a slit. There is. here,
The gas pressure during plasma film formation is 1 Torr or less, and the behavior of the gas flow is not in the laminar flow region but in the intermediate flow region where the nature of the diffusion flow is great. Therefore, the gas pressure in the i-layer deposition chamber is
Even if the gas pressure is set to be slightly higher than the gas pressure in the n-layer deposition chamber, it is not possible to prevent the dopant gas from entering the i-layer deposition chamber. An effective measure is to confine the film-forming source gas in the film-forming region as much as possible, and to suppress the mutual diffusion of the film-forming source gas due to the diffusion flow by using multiple slits.
The conventional configuration is unsatisfactory from this point of view. More specifically, in the configuration described in Japanese Patent Publication No. 4-32533, since the film-forming raw material gas is likely to flow out in the width direction of the long flexible substrate, The gas atmosphere is almost uniform, and the film forming chambers are separated from each other by only one slit. Therefore, in the configuration of this continuous plasma film forming apparatus, there is a problem that the dopant gas is easily mixed in the i-layer film forming chamber, and the dopant is easily mixed in the i-layer.

[0006]

As described above, the conventional continuous plasma film forming apparatus has a fundamental problem. An object of the present invention is to solve the problems of the above-mentioned conventional techniques. Firstly, in a compact device configuration with a small device installation area, plasma discharge caused by bending of a flexible substrate in the width direction. Provided is a continuous plasma film forming apparatus on a flexible substrate, which has a structure of high film forming uniformity by suppressing a variation in a distance from an electrode and also suppresses mutual diffusion of a film forming material gas between adjacent film forming chambers. Second, high productivity,
Another object of the present invention is to provide a continuous plasma formation method on a flexible substrate in which the film compositions are less likely to be mixed with each other, especially the dopants are not mixed with each other, when semiconductor layers having different compositions are formed in layers.

[0007]

[Means for Solving the Problems] The first purpose is (1)
A flexible substrate installed in the vacuum chamber is bent to form a substantially cylindrical body, and a substantially closed space surrounded by the cylindrical body and a pair of structures closing both end surfaces of the cylindrical body is formed. A structure in which a decomposition film forming gas is introduced into the substantially closed space, plasma discharge is generated in the space, and film growth is performed on the flexible substrate surface forming the inner wall of the cylindrical body. More specifically, (2) the flexible substrate is a long substrate, a part of which is bent in the length direction and wound around a pair of disc-shaped bodies. To form a substantially closed space having a substantially cylindrical shape, and more specifically, (3) there are a plurality of portions forming the above substantially closed space, Plasma in which the flexible substrate moves in the closed space forming portion and a film is laminated on the surface of the flexible substrate on the side forming the inner wall of the cylindrical closed space. More preferably, it is a film device, and (4) the vacuum chamber is divided into a plurality of compartments so as to prevent mutual diffusion of the decomposition film-forming gas, and the plasma film formation is internally performed in the compartments. The substantially cylindrical closed space forming portion is disposed, and the flexible substrate moves on the plurality of substantially cylindrical closed space forming portions to form an inner wall of the cylindrical closed space. A plasma film forming apparatus having a structure in which films having different compositions are laminated on a flexible substrate surface, and from the viewpoint of productivity, preferably (5) the flexible substrate is a long substrate, A plasma film forming apparatus having a structure in which the substrate continuously moves in the substantially cylindrical closed space forming portion and a film is laminated on the surface of the flexible substrate on the side forming the inner wall of the cylindrical closed space. Further, preferably, (6) the decomposition film forming gas introduction mechanism and the inside of the substantially cylindrical closed space forming portion described above. And a plasma film forming apparatus having an exhaust hole, and more preferably (7) having a pressure detection sensor inside the substantially cylindrical closed space forming part, and an exhaust system connected to the exhaust hole. A plasma film forming apparatus having an exhaust conductance control mechanism, and more preferably, (8) an exhaust hole is provided inside the substantially cylindrical closed space forming portion, and an exhaust hole is also provided outside the forming portion. A plasma film forming apparatus having, more specifically, (9) the vacuum chamber is divided into a plurality of sections so as to inhibit the mutual diffusion of the decomposition film forming gas, in each divided section Of the plasma film forming apparatus having an exhaust hole inside and outside the portion that forms the substantially cylindrical closed space, and more specifically, (10)
The flexible substrate is a conductive substrate, the substrate is at ground potential, a rod-shaped or column-shaped electrode is installed inside the substantially cylindrical closed space, and high frequency power or pulsed power is applied to the electrode. And a plasma film forming apparatus configured to generate a plasma discharge, preferably, (11)
This can be achieved by using the plasma film forming apparatus in which the electric power supplied to the rod-shaped or cylindrical electrode installed inside the substantially cylindrical closed space forming portion is a high frequency of 1 MHz or more.

The second object is (12) the gas containing a hydrogenated silicon compound is plasma-decomposed by using the above film forming apparatus, and hydrogenated amorphous silicon or hydrogen is formed on the surface of the flexible substrate. Microcrystalline silicon, or a plasma film forming method for forming an amorphous or microcrystalline semiconductor film containing germanium, carbon, oxygen or nitrogen, and in particular, (13) on the surface of the flexible substrate A plasma film forming method of continuously laminating semiconductor layers having different compositions, and (14) a semiconductor layer containing a dopant and substantially no dopant on the surface of the flexible substrate. A plasma film forming method in which a semiconductor layer is continuously laminated is formed, or, (15) the surface of the flexible substrate is a semiconductor layer containing a dopant of one conductivity type and a dopant of a conductivity type opposite to that of the semiconductor layer. Inclusion This can be achieved by a plasma film forming method in which the semiconductor layer to be formed is continuously laminated.

[0009]

Operation: Operation of the apparatus and method of the present invention
The effects are as follows. (1) A flexible substrate installed in a vacuum chamber is bent to form a substantially cylindrical body, and the substantial body is surrounded by the cylindrical body and a pair of structures that close both end surfaces of the cylindrical body. Form a closed space,
A decomposition film forming gas is introduced into the substantially closed space, plasma discharge is generated in the space, and a film is grown on the surface of the flexible substrate forming the inner wall of the cylindrical body. By this, the length of the film forming apparatus can be shortened to about 1/3. As a result, the installation area of the device can be reduced to about 1/3. Further, bending the flexible substrate to form the tubular body increases the rigidity of the flexible substrate in the width direction and suppresses the bending in the width direction. As a result, the distance from the plasma discharge cathode becomes stable, and the uniformity of film formation can be kept high.
Further, in the above configuration, the decomposed film forming gas is suppressed from flowing out in the width direction of the flexible substrate, and the decomposed film forming gas is suppressed from flowing out of the film formation region.

(2) The flexible substrate is a long substrate, and a part of it is bent in the length direction and wound around a pair of disc-shaped bodies to form a substantially cylindrical substantially closed space. By using the flexible substrate described above, the productivity can be increased and the above advantages can be utilized. In addition,
The disc-shaped body includes a columnar body, and further includes a hollow columnar body having one end opened. Further, the pair of disc-shaped bodies may be connected by a pillar. If the portion of the disk-shaped body that is in contact with the end of the flexible substrate is tapered, the sealing performance in this direction will be good. Further, by making at least the outer periphery of the disc-shaped body rotate in synchronization with the movement of the long flexible substrate, the sealing performance of this portion can be favorably maintained.

(3) There is a plurality of portions forming the above-mentioned substantially closed space, and the flexible substrate moves through the cylindrical closed space forming portion to form an inner wall of the cylindrical closed space. With the structure in which the film is laminated on the surface of the flexible substrate, it is possible to suppress undesired mixture of film constituents when laminating films having different compositions. This is because the decomposition film forming gas is prevented from flowing out of the film forming region, and at least the slit structure for preventing the decomposition film forming gas from diffusing into the adjacent film forming region is provided. This is because there are two stages.

(4) The vacuum chamber is divided into a plurality of compartments so as to prevent the mutual diffusion of the decomposition film-forming gas, and a substantially cylindrical shape in which the plasma film formation is performed inside the compartments. A closed space forming portion is disposed, the flexible substrate moves in the plurality of substantially cylindrical closed space forming portions, and a different composition is formed on the surface of the flexible substrate on the side forming the inner wall of the cylindrical closed space. By adopting a constitution in which the films of (1) are laminated, it is possible to further suppress the undesired mixture of the film constituents without enlarging the device. This is because there is at least 3 slit structures that prevent the decomposed film forming gas from diffusing into the adjacent film forming region.
This is because it becomes a step.

(5) The flexible substrate is an elongated substrate, and the substrate continuously moves in the substantially cylindrical closed space forming portion to form an inner wall of the cylindrical closed space. With the structure in which the film is laminated on the surface of the flexible substrate, the productivity can be increased, and the above advantages can be utilized.

(6) By disposing the decomposition film forming gas introduction mechanism and the exhaust hole inside the substantially cylindrical closed space forming portion, the decomposition film forming gas is discharged to the outside of the decomposition film forming region. Outflow can be effectively suppressed.

(7) By providing a pressure detection sensor inside the substantially cylindrical closed space forming portion and an exhaust conductance control mechanism in the exhaust system connected to the exhaust hole, the plasma generation is improved. The controllability of the film conditions can be improved.

(8) The gas leaked from the plasma film forming section is formed by providing the exhaust hole inside the substantially cylindrical closed space forming portion and the exhaust hole outside the forming portion. It is possible to effectively prevent diffusion and penetration into other plasma film forming portions.

(9) The vacuum chamber is divided into a plurality of compartments so as to prevent mutual diffusion of the decomposition film-forming gas, and a portion forming a substantially cylindrical closed space in each of the compartments. With the structure having exhaust holes inside and outside, it is possible to further effectively prevent the decomposed film forming gas leaked from one plasma film forming unit from diffusing into another plasma film forming unit. You can This is because the intermediate exhaust unit has at least two stages.

(10) The flexible substrate is a conductive substrate,
The substrate is set to a ground potential, a rod-shaped or columnar electrode is installed in the substantially cylindrical closed space, and high-frequency power or pulsed power is supplied to the electrode to generate plasma discharge. As a result, plasma discharge can be uniformly formed in the length direction of the flexible substrate. In order to specify the plasma discharge area in the width direction of the flexible substrate, the area of the rod-shaped or columnar electrode where discharge is not desired is covered with an earth shield, or the rod-shaped or circular area where discharge is not desired Measures may be taken such as increasing the thickness of the columnar electrode to reduce the distance from the conductive substrate. In the above configuration in which the electrodes are arranged concentrically, the rod-shaped or columnar electrode serves as a cathode, and the electric field strength on the side of the rod-shaped or columnar electrode becomes strong, so that It also has the advantage that unwanted ion injection is suppressed. The importance of this effect can be understood from the fact that the substrate is always arranged on the anode side in the formation of the hydrogenated amorphous silicon semiconductor film by the parallel plate plasma deposition apparatus. Note that the conductive substrate may have an insulating layer formed on its film-forming surface as long as it can be grounded. However, when using a high frequency of 1 MHz or more for plasma discharge, it is desirable to secure electrical connection at the widthwise end of the substrate on the high frequency power input side. This is because the rod-shaped or column-shaped electrode and the conductive substrate form a coaxial line for high frequencies.

(11) When the power supplied to the rod-shaped or cylindrical electrode installed inside the above-mentioned substantially cylindrical closed space forming portion is set to a high frequency of 1 MHz or more, the decomposition efficiency of the raw material gas is increased, It is also effective in enhancing controllability of plasma discharge. In particular, when a high frequency of 100 MHz or more is used, the decomposition efficiency of the raw material gas can be significantly increased. When the decomposition efficiency of the raw material gas is high, the raw material gas is mostly consumed in the plasma discharge region, which leads to suppression of undesired mutual diffusion of the raw material gas. In this case, since the electrode arrangement described above constitutes a coaxial line for high frequency,
Plasma discharge with high circumferential uniformity can be obtained.

(12) As described above, the plasma film forming apparatus of the present invention is an apparatus suitable for forming an amorphous or microcrystalline semiconductor film, and a gas containing a silicon hydride compound is used as a plasma. Decomposes, hydrogenated amorphous silicon or hydrogenated microcrystalline silicon on the flexible substrate surface, or
By applying the method to a plasma film forming method for forming an amorphous or microcrystalline semiconductor film containing germanium, carbon, oxygen, or nitrogen, the manufacturing cost of an amorphous semiconductor device can be reduced.

(13) In particular, when semiconductor layers having different compositions are continuously laminated on the surface of a flexible substrate, a laminated amorphous semiconductor device in which layer constituent elements are less likely to be mixed with each other is reduced. It can be manufactured at a cost.

(14) In particular, when a semiconductor layer containing a dopant and a semiconductor layer containing substantially no dopant are continuously laminated on the surface of the flexible substrate, the dopant is substantially contained in the surface. It is possible to manufacture a high-performance amorphous semiconductor device in which a semiconductor layer that does not contain a dopant is less mixed with a low cost.

(15) In the case where a semiconductor layer containing a dopant of one conductivity type and a semiconductor layer containing a dopant of the opposite conductivity type are continuously laminated on the surface of the flexible substrate, the reverse polarity is applied. It is possible to continuously form semiconductor layers in which the dopant is less mixed, and a high-performance amorphous semiconductor device having such a configuration can be manufactured at low cost.

[0024]

EXAMPLES Hereinafter, the plasma film forming apparatus and the film forming method of the present invention will be specifically described with reference to Examples.

[0025]

[Embodiment 1] FIG. 1 is a schematic sectional view showing a schematic structure of an embodiment of the continuous plasma film forming apparatus of the present invention.
It is intended for the production of amorphous silicon solar cells with an i-n junction. Here, 1 is a flexible substrate (stainless steel), an insulating layer is formed on one surface thereof, and a metal conductive layer is separately formed on the surface thereof. This surface is the surface on which the amorphous silicon solar cell is formed, but in the case of FIG. 1, that surface is the lower surface.

The movement of the substrate in this apparatus is performed as follows. That is, the flexible substrate 1 wound on the roll 2 passes through the slit 4 through the guide roll 3 and is fed into the n-layer deposition chamber 5, and also passes through the slit 6 and moves to the i-layer deposition chamber 7. Then, it passes through the slit 8 and moves to the p-layer film forming chamber 9, is discharged through the slit 10, and is wound up by the winding roll 12 through the guide roll 11. Each of these chambers, including the roll storage chamber, is evacuated,
In particular, an exhaust hole is provided near the slits 6, 8 and 10.

In each layer forming chamber, the flexible substrate 1 is wound around a pair of disc-shaped bodies (not shown) via a guide roll 12 to form a substantially cylindrical body 13 and a guide roll 14 is formed. It passes through the slit and is sent out to the next room. Here, the pair of disc-shaped bodies around which the flexible substrate 1 is wound are configured to rotate as the flexible substrate 1 advances. In addition, a rod-shaped or cylindrical center electrode 15 is provided inside the tubular body 13, and the tubular body 13 made of the flexible substrate 1 is provided.
The structure is such that a plasma discharge is generated in the gap portion 16 between and. Therefore, this gap portion is the plasma discharge portion, and the decomposition film forming gas is introduced therein, but from the viewpoint of uniformity,
It is desirable that the decomposed film forming gas be discharged from the central electrode 15 toward the cylindrical body 13 formed by the flexible substrate 1. A dedicated exhaust hole (not shown) is provided at one end of the plasma discharge portion 16 surrounded by the tubular body 13 formed of the flexible substrate 1, and
A sensor (not shown) for monitoring the pressure of the plasma discharge unit 16 may be installed, and a dedicated exhaust system may be provided with an exhaust conductance control mechanism (not shown) to control the reaction pressure. desirable. In addition, the flexible substrate 1
A substrate heating mechanism (not shown) by a lamp heater is installed outside the tubular body 13 by 150 ° C. to 3 ° C.
A film is formed by heating to 00 ° C.

[0028]

Second Embodiment Since the structure of the present invention has a great advantage not only in the case of the multi-chamber film forming apparatus but also in the case of the single-chamber film forming apparatus, the detailed structure of the plasma discharge part and its effect will be described. ,
This will be described with reference to the single chamber continuous plasma deposition apparatus shown in FIG. It should be noted that (a) of the figure shows the entire structure, and (b) shows the AA 'cross section of the plasma discharge part of (a).

In (a), reference numeral 1 is a flexible substrate, which is tightly wound around the rotating disk 21. The rotary disk 21 is meshed with the fixed disk 20, and the rotary disk 21 and the fixed disk 20 form an end disk, and the flexible substrate wound in a cylindrical shape constitutes a substantially sealed discharge space. There is. This almost sealed discharge space has a dedicated exhaust hole
23 and pressure monitor terminal 24 are installed. Further, an exhaust conductance control mechanism is provided in the exhaust line connected to the exhaust hole 23, and in combination with a pressure monitor, the reaction pressure of the plasma discharge part is controlled. Also,
A center electrode 15 is fixed to the center axis of the cylinder through an insulator 22, and a film forming gas can be supplied from the center electrode 15 in a radial direction to obtain high uniformity of film forming characteristics. .

The ground connection of the flexible substrate 1 is the guide roll 1
Although it can be performed through 2, 14, etc., when a high frequency of 1 MHz or more is supplied to the center electrode 15 to generate plasma discharge, the disk-shaped body 20, 21 around which the flexible substrate 1 is wound.
Is preferably connected to the ground and the electrical connection therewith is tight. This is to form a coaxial line for high frequencies. By the action of the guide rolls 12 and 14,
The flexible substrate 1 can be tightly wound around a pair of disc-shaped bodies, and when the flexible substrate 1 is stainless steel,
A tight electrical connection can be obtained if the stainless steel at the end is exposed. When the flexible substrate is an insulator such as polyimide, it is necessary to install the ground electrode in a substantially cylindrical shape outside the cylindrical body 13 formed of the flexible substrate 1. However, such a configuration is not possible. It's easy. The above configuration is a configuration in which the electric field is concentrated on the side of the central electrode 15, and also has an action of suppressing the incidence of undesired ions on the film formation surface. The power supplied to the center electrode 15 is generally a high frequency of 13.56 MHz, but may be a microwave of 2.45 MHz. This is because the electrode arrangement is configured to form a coaxial line. Further, even if pulsed power is used, no particular problem occurs. However, in order to improve the decomposition efficiency of the raw material gas and reduce the outflow of the raw material gas from the film formation region, it is desirable to use microwaves. By bending the flexible substrate 1 into a cylindrical shape, the rigidity in the width direction becomes high, and the distance from the center electrode 15 becomes substantially uniform, so that the uniformity of plasma discharge can be ensured.

The above structure will be described by returning to FIG. 1 from the viewpoint of confining the decomposition film forming gas.
The outflow of the decomposed film forming gas from the width direction of the flexible substrate 1 from 16 is suppressed, and the outflow of the decomposed film forming gas from the plasma discharge part 16 is caused by the gap between the guide roll 12 and the guide roll 14. Only happens. This outflow can be reduced by adding a guide roll 17. The guide roll 17 has a structure in which only the end portion of the flexible substrate 1 is in contact with the film forming surface and a gap is maintained. The guide roll 17 also has a function of preventing the film-forming surfaces of the flexible substrate 1 from rubbing against each other.

By the way, since a slit for suppressing mutual diffusion of the decomposition film forming gas is provided between the film forming chambers,
The plasma discharge film forming sections are separated by at least three decomposition film forming gas mutual diffusion suppressing mechanisms.
In the conventional configuration in which the flexible substrate 1 moves in a substantially straight line,
Since the corresponding decomposition film forming gas mutual diffusion suppressing mechanism is only one stage, by adopting the above-mentioned configuration of the present invention, the mixing of the decomposition film forming gas supplied to the other plasma discharge film forming section is significantly suppressed. Will be done. As described above, the structure of this example is based on the assumption of manufacturing a hydrogenated amorphous silicon solar cell having a pin structure.
The mixture of dopants from the p-layer film formation section to the i-layer film formation section is greatly suppressed, and it is possible to continuously manufacture solar cells with high photoelectric conversion efficiency.

In the above example, an example of manufacturing a hydrogenated amorphous silicon solar cell having only one pin structure was described, but the pin structure has two layers or two layers. In the case of manufacturing a laminated solar cell having a structure in which three layers are laminated, the plasma discharge film forming chamber may have six chambers or nine chambers or more. In order to manufacture such a stacked solar cell with a manufacturing apparatus having a conventional structure in which the flexible substrate 1 moves in a substantially straight line, in order to suppress mutual diffusion of dopants, a p-layer deposition chamber and an n-layer are formed. Although it was necessary to provide an intermediate exhaust chamber with the film forming chamber, the configuration of the present invention makes it possible to suppress interdiffusion of dopants without providing such an intermediate exhaust chamber.

Although the plasma film forming apparatus and the plasma film forming method of the present invention have been described by taking the production of a solar cell as an example, the present invention is not limited to this and can be applied to thin film production in general. You can

[0035]

As described above, by using the plasma film forming apparatus and the plasma film forming method as the apparatus and method of the present invention, the problems of the prior art can be solved. In a compact device configuration in which the device installation area is small, a variation in the gap between the flexible substrate and the plasma discharge electrode caused by the bending of the flexible substrate in the width direction is suppressed, and the film formation is highly uniform. To provide a continuous plasma film forming apparatus on a flexible substrate in which mutual diffusion of film forming source gases between chambers is suppressed. Secondly, semiconductor layers having high productivity and different compositions are laminated and formed. In this case, it was possible to provide a continuous plasma formation method on a flexible substrate in which the film composition was less likely to be mixed with each other, especially the dopant was less mixed with each other.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing the configuration of an example of a multi-chamber continuous plasma deposition apparatus of the present invention.

FIG. 2 is a schematic cross-sectional view showing the configuration of an example of a single-chamber continuous plasma deposition apparatus of the present invention.

[Explanation of symbols]

1 ... Substrate, 2, 12 ... Roll, 3, 11 ... Guide roll,
4, 6, 8, 10 ... Slits, 5 ... n layer deposition chamber, 7 ... i
Layer deposition chamber, 9 ... p Layer deposition chamber, 12, 14 ... Guide roll, 1
3 ... Substrate tubular body, 15 ... Center electrode, 16 ... Plasma discharge part, 1
7 ... Auxiliary guide roll, 18 ... Vacuum chamber, 19 ... Vacuum chamber wall, 20
… Fixed disk, 21… Rotating disk, 22… Insulator, 23… Exhaust hole,
24 ... Pressure monitor.

Claims (15)

[Claims] 1. A flexible substrate installed in a vacuum chamber is bent to form a substantially tubular body, and the tubular body and a pair of structural bodies closing both end surfaces of the tubular body substantially closes the tubular body. A mechanism for forming a space and introducing a decomposed film forming gas into the substantially closed space,
A plasma film forming apparatus comprising: a mechanism for generating plasma discharge in the space to grow a film on a surface of a flexible substrate forming an inner wall of the cylindrical body. 2. The flexible substrate is a long substrate, and a portion of the flexible substrate is bent in the length direction and wound around a pair of disc-shaped bodies to form a substantially cylindrical substantially closed space. The plasma film forming apparatus according to claim 1, wherein the plasma film forming apparatus is a flexible substrate. 3. A plurality of portions forming the substantially closed space are present, and the flexible substrate moves through the cylindrical closed space forming portion to form an inner wall of the cylindrical closed space. 3. A structure in which a film is laminated on the surface of a flexible substrate.
The plasma film forming apparatus as described in any one of 1. 4. The vacuum chamber is divided into a plurality of compartments so as to prevent mutual diffusion of the decomposition film-forming gas, and a substantially cylindrical closed structure for internally performing the plasma film formation in the compartments. A space forming portion is arranged, the flexible substrate moves in the plurality of substantially cylindrical closed space forming portions, and the flexible substrate surface on the side forming the inner wall of the cylindrical closed space has a different composition. The plasma film forming apparatus according to claim 1, wherein the film is laminated. 5. The flexible substrate is a long substrate, and the substrate moves continuously in the substantially cylindrical closed space forming portion to form an inner wall of the cylindrical closed space. 4. A structure in which a film is laminated on the surface of the flexible substrate,
4. The plasma film forming apparatus according to any one of 4 above. 6. The plasma film forming method according to claim 1, wherein a decomposition film forming gas introducing mechanism and an exhaust hole are provided inside the substantially cylindrical closed space forming portion. apparatus. 7. A pressure detecting sensor is provided inside the substantially cylindrical closed space forming portion, and an exhaust conductance control mechanism is provided in an exhaust system connected to the exhaust hole. 6. The plasma film forming apparatus according to any one of 6. 8. An exhaust hole is provided inside the substantially cylindrical closed space forming portion, and an exhaust hole is also provided outside the forming portion, according to any one of claims 1 to 7. Plasma deposition system. 9. The vacuum chamber is divided into a plurality of compartments so as to hinder the mutual diffusion of the decomposition film forming gas, and a portion of each divided compartment that forms a substantially cylindrical closed space. 5. The plasma film forming apparatus according to claim 4, wherein the inside and outside have exhaust holes. 10. The flexible substrate is a conductive substrate, the substrate is at ground potential, and rod-shaped or column-shaped electrodes are installed inside the substantially cylindrical closed space, and high-frequency waves are applied to the electrodes. The plasma film forming apparatus according to claim 1, wherein the plasma film forming apparatus is configured to generate a plasma discharge by supplying electric power or pulsed electric power. 11. A plasma film forming apparatus, wherein electric power supplied to a rod-shaped or columnar electrode installed inside the substantially cylindrical closed space forming portion is a high frequency of 1 MHz or more. 12. The film-forming apparatus according to claim 1, wherein a gas containing a silicon hydride compound is plasma-decomposed and hydrogenated amorphous silicon or hydrogenated on the surface of the flexible substrate. A plasma film forming method comprising forming an amorphous or microcrystalline semiconductor film containing microcrystalline silicon or germanium, carbon, oxygen or nitrogen. 13. The plasma film forming method according to claim 12, wherein semiconductor layers having different compositions are continuously laminated on the surface of the flexible substrate. 14. The plasma process according to claim 12, wherein a semiconductor layer containing a dopant and a semiconductor layer containing substantially no dopant are continuously laminated on the surface of the flexible substrate. Membrane method. 15. A semiconductor layer containing a dopant of one conductivity type and a semiconductor layer containing a dopant of an opposite conductivity type are continuously laminated on the surface of the flexible substrate. 12. The plasma film forming method described in 12.