JP3617664B2 - Thin film photoelectric conversion device manufacturing equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an apparatus for manufacturing a thin film photoelectric conversion element that forms a thin film on a flexible substrate by a stepping roll method among the apparatuses for manufacturing a thin film solar cell.
[0002]
[Prior art]
Thin film solar cells are expected to become the mainstream of future solar cells because they are thin and lightweight, inexpensive to manufacture, and easy to increase in area.
[0003]
Conventional thin-film solar cells have used glass substrates, but research and development of flexible solar cells using plastic films and metal films has been promoted in terms of weight reduction, workability, and mass productivity. In the thin film solar cell, for example, a plurality of photoelectric conversion elements (or cells) formed by laminating a metal electrode layer, a photoelectric conversion layer made of a thin film semiconductor layer, and a transparent electrode layer on a flexible electrically insulating film substrate are formed. . Taking advantage of this flexibility, mass production became possible by a roll-to-roll method or a stepping roll method.
[0004]
Both of the above systems are provided with a substrate transport means by a plurality of rolls, the former is a method of continuously forming a film on a substrate that moves continuously in each film forming chamber, and the latter is simultaneously stopped in each film forming chamber. In this method, a film is formed on a substrate and the substrate portion after film formation is sent to the next film formation chamber.
[0005]
The stepping roll type film forming apparatus is superior in that the characteristics of each thin film can be stably obtained and the apparatus can be made compact because it can prevent gas mutual diffusion between adjacent film forming chambers. For example, Japanese Patent Laid-Open No. 6-292349, Japanese Patent Laid-Open No. 7-6953, Japanese Patent Laid-Open No. 7-2221025, Japanese Patent Laid-Open No. 8-250431, Japanese Patent Laid-Open No. 8-293491, etc. Yes.
[0006]
FIG. 11 is a conceptual diagram showing an example of the configuration of a stepping roll film forming type vacuum film forming apparatus having a plurality of film forming chambers in a common vacuum chamber. The apparatus shown in FIG. 11 includes an unwinder chamber 290 for unwinding a flexible substrate, a metal electrode layer (rear connection electrode layer), a photoelectric conversion layer (a-Si layer), a transparent electrode layer (ITO layer), and the like. A film forming chamber 280 serving as a plurality of independent processing spaces for forming the substrate, and a winder chamber 291 for winding, and the substrate 201 is rolled out from the core 282 and wound on the core 283. A film is formed in the film formation chamber 280. The common chamber 281 houses a plurality of film formation chambers 280 therein.
[0007]
In the film formation chamber, film formation is performed by sputtering film formation or plasma chemical vapor deposition (hereinafter referred to as plasma CVD method). For example, in the stepping roll method for forming a film by plasma CVD, the film forming chamber is opened-the substrate is moved by one frame-the film forming chamber is sealed-the raw material gas is introduced-the pressure is controlled-the discharge is started-the discharge is terminated- The operation consisting of opening the film forming chamber is repeated.
[0008]
Further, from the viewpoint of improving mass productivity, the present applicant has proposed a plasma CVD method stepping roll method in which a photoelectric conversion layer is simultaneously formed on two rows of flexible substrates that are transported in parallel (Japanese Patent Laid-Open No. Hei. 8-293491).
[0009]
12 and 13 show an apparatus described in the above-mentioned Japanese Patent Application Laid-Open No. 8-293491. FIG. 12 shows the state of the apparatus during film formation as a plan sectional view, and FIG. 13 shows the state of the film formation chamber during film formation as an enlarged view. The thin film photoelectric conversion device manufacturing apparatus of FIG. 12 includes a feeding chamber 11, a preliminary vacuum chamber 12, a film forming vacuum chamber 13, and a winding chamber 14, and the two flexible substrates 1 are wound up from the feeding chamber 11. It is conveyed to the chamber 14. A high-voltage electrode 21 and a ground electrode 22 having a heater 23 are disposed opposite to each other in the film-forming vacuum chamber 13, and a− is formed on the surface of the substrate 1 stopped in the meantime by plasma CVD under application of a high-frequency voltage. A Si-based thin film is formed.
[0010]
As shown in an enlarged view in FIG. 13, the high-voltage electrode 21 has a lid shape, and the substrate 1 is in close contact with the end surface of the high-voltage electrode 21 via the seal block 8, thereby forming a film formation chamber 5 that can be kept airtight. . One high-voltage electrode 21 is provided for each substrate 1, but is connected to the back surface of the substrate 1 via an exhaust block 9 made of an insulating material. The exhaust block 9 is brought into close contact with the high voltage electrode 21 through the sealing material 91, and has a pressure control function (not shown) through the exhaust port 72 opened in the exhaust block 9 and the opening 25 on the back surface of the high voltage electrode 71. The film forming chambers 5 are collectively maintained at the film forming pressure by the exhaust system.
[0011]
Application of a voltage between the high voltage electrode 21 and the ground electrode 22 generates plasma 6 to form a film. Since the two film forming chambers 5 are electrically insulated by the exhaust block 9, the plasma 6 can be controlled for each film forming chamber. When the ground electrode 22 is moved up and down several tens of millimeters by the actuator 24 shown in FIG. 2 after the film formation, the substrate 1 held by the ground electrode 22 is also released and moved in the direction of the arrow 41. .
[0012]
By the way, although the high voltage electrode 21 is exposed in the space of the film forming vacuum chamber 13, even when high frequency power is applied to the high voltage electrode 21, the pressure of the film forming vacuum chamber 13 during film formation is reduced to 0.1 Pa or less. By keeping it, discharge in the vacuum chamber 13 for film formation is suppressed. However, since the pressure in the exhaust block 9 is 10 to 170 Pa (practically 40 to 140 Pa) at the time of film formation, it is easily discharged between the two high voltage electrodes. Although there is a method of adjusting and controlling the phase between the electrodes, there is a problem in reality, and in order to avoid discharge between the two high voltage electrodes, the exhaust block 9 is an insulator and the length is 100 mm or more.
[0013]
By the way, in the case of the conventional apparatus for manufacturing a thin film photoelectric conversion element, the width of the vacuum chamber for film formation is increased by the amount of 100 mm or more, the volume of the vacuum chamber is increased, and a large exhaust system is required. There is a problem that the overall cost of the apparatus including the cost of the above increases. Therefore, in order to solve the above problems, the applicant of the present application provided a partition wall 92 for blocking gas conduction in the through hole of the exhaust block 90 as shown in FIG. An apparatus for manufacturing a thin film photoelectric conversion element has been proposed (see Japanese Patent Application No. 11-229750) having a configuration in which it is provided in communication with each through-hole 73 divided by a partition wall 92.
[0014]
The apparatus shown in FIG. 14 includes the back wall of the substrate 1 and the high voltage electrode 21 in order to improve the safety of the seal by keeping the temperature of the sealing material 91 of the exhaust block 90 low in addition to the provision of the partition wall 92. Between the side surface portion and the side surface portion so as to allow the gas for forming the film to flow therethrough between the side surface portion and substantially the entire width of the back surface portion. A heat shield 27 for the box-shaped sealing material is disposed, the shield is electrically connected to the high voltage electrode, and the film forming gas can flow from the gap to the opening of the back surface portion. It is configured as follows.
[0015]
For convenience of explanation of the present invention to be described later, FIGS. 8 to 10 show simplified views of the configuration of the conventional thin film photoelectric conversion device manufacturing apparatus. FIG. 8 corresponds to FIG. 13 described above, and FIG. 10 corresponds to FIG. 14, and each shows an apparatus for forming a film by transferring two rows of substrates in parallel. On the other hand, FIG. 9 shows an apparatus for forming a film on one row of substrates. 8 to 10, the same functional members in the apparatus shown in FIGS. 12 to 14 are denoted by the same reference numerals and description thereof is omitted.
[0016]
8 to 10, members not shown in FIGS. 12 to 14 are added to the vacuum exhaust system, and the exhaust system in FIGS. 8 to 10 is an insulating exhaust made of an electrically insulating material. An exhaust system including an exhaust line having a line 59 and a metal exhaust line 56 made of a metal material downstream of the line 59 and an exhaust unit 58 is shown. Further, a pressure control valve 57 is provided in the front stage of the exhaust unit 58, and a diagram is shown in which the pressure control of the film forming gas is performed during film formation. Further, in FIG. 8 or FIG. 10, the insulating exhaust line 59 is composed of an insulating block 9 or 90 and an insulating pipe 59.
[0017]
[Problems to be solved by the invention]
By the way, even the conventional improved thin film photoelectric conversion device manufacturing apparatus proposed in the above Japanese Patent Application No. 11-229750 can be used under conditions of relatively low film formation pressure (high vacuum) or high high frequency output. It has been found that there is a problem that discharge occurs in the exhaust line installed at the rear of the high-frequency high-voltage electrode, resulting in high-frequency power loss or film adhesion in the device other than the film formation region. This will be described later as a comparative example of the present invention). The power loss or the film adhesion in the apparatus other than the film formation region makes it difficult to increase the throughput of the film formation apparatus, and increases the maintenance frequency.
[0018]
The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to improve the suppression of discharge in the exhaust line as compared with the conventional technique, to increase the throughput of the film forming apparatus and to maintain the maintenance frequency. The aim is to reduce the mass production cost of the thin film photoelectric conversion element comprehensively.
[0019]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, the invention of claim 1 has a back surface portion parallel to the flexible substrate surface to be conveyed and a side wall portion having an end surface capable of airtight contact with the substrate, and the back surface portion. Is provided on the outside of the substrate facing the high voltage electrode, a ground electrode having a heater for heating the substrate, and provided on the back surface of the high voltage electrode, An insulating exhaust line made of an electrically insulating material having a through hole communicating hermetically with the opening of the back surface by a sealing material and having a vacuum exhaust port communicating with the through hole; and the high voltage electrode, A film forming gas is introduced into a film forming space formed between the substrate and a high frequency voltage is applied between the high voltage electrode and the ground electrode to generate a discharge between the substrate and the high voltage electrode. Thin film photoelectric conversion configured to form a thin film on one surface In the manufacturing apparatus of the child, the discharge preventing means for preventing the discharge by reducing the conductance of the gas flow in said insulating exhaust line, and those with in said insulating exhaust line.
[0020]
For example, in the device described in claim 1, the discharge prevention means is composed of a plurality of gas flow baffle plates made of an electrically insulating material (Claim 2), or the discharge prevention means is an electric It shall consist of a mesh-like member which consists of an insulating material (Claim 3).
[0021]
According to the above configuration, the electrons in the gas flow collide with the baffle plate or the mesh member and disappear, so that the electron density in the gas is lowered and the discharge cannot be maintained. By utilizing this principle, it is possible to suppress discharge even under conditions of relatively low film formation pressure or high frequency output.
[0022]
Further, in the above-described first aspect, in place of the discharge preventing means for preventing discharge by reducing the conductance of the gas flow, the first disposed in the back opening of the high-voltage electrode. Metal mesh, a second metal mesh disposed on the insulating exhaust line side in the vicinity of the first metal mesh and electrically grounded, and electrical insulation interposed between the two metal meshes A discharge preventing means having a double mesh structure made of an insulating sheet made of a conductive material is provided.
[0023]
The double mesh configuration uses a dischargeable condition indicated by a Paschen curve (a relationship between a discharge start voltage and a distance between converted electrodes [pressure × distance between electrodes]). By placing the two meshes provided in close proximity to each other, the discharge start voltage can be made extremely high so as not to cause discharge. The invention of claim 4 is more effective in suppressing discharge than the inventions of claims 1 to 3.
[0024]
Further, as the constituent material of the exhaust block, as in the invention of claim 5, at least one material of fluororesin, glass or ceramics can be applied. For example, only the insulating sheet according to the invention of claim 4 is applicable. It is also possible to form a plurality of materials, such as fluorinated resin and other ceramics.
[0025]
Furthermore, in the thing in any one of Claim 1 thru | or 5, in order to enable manufacture of a thin film photoelectric conversion element simultaneously on two rows of flexible substrates, the manufacturing apparatus of a thin film photoelectric conversion element is conveyed in parallel. Between the two rows of flexible substrates, each having a back surface portion parallel to the substrate surface and a side wall portion having an end surface capable of airtight contact with the substrate, and Two high-voltage electrodes each having an opening on the back surface, two ground electrodes provided on the outside of each of the substrates so as to face the high-voltage electrodes and having a heater for heating the substrate, and the two Insulation made of an electrically insulating material provided between the back portions of the high-voltage electrode, having a through hole that is hermetically communicated with the opening of the back portion by a sealing material, and having a vacuum exhaust port that communicates with the through hole An exhaust line, the high voltage electrode and each base A gas for film formation is introduced into a film formation space formed between the substrate and the high-voltage electrode between the high-voltage electrode and the ground electrode, and a discharge is generated between the substrate and the high-voltage electrode. It is preferable that a thin film be formed on one surface (claim 6).
[0026]
Furthermore, in any one of Claims 1 thru | or 6, in order to flow the said film-forming gas between the said board | substrate and the back surface part of a high voltage electrode in parallel with this back surface part. A heat shield for the plate-like or box-like sealing material made of a conductive material is disposed over the substantially entire width of the back surface portion with the gap between the side surface portion, and this shield body is disposed on the high voltage electrode. And the gas for film formation is configured to be able to flow from the gap to the opening of the back surface portion (Claim 7). The safety of the seal can be improved by keeping the temperature at a low level.
[0027]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention will be described below with reference to the drawings.
[0028]
1 to 3 show schematic configurations of different embodiments of the present invention. In FIG. 1 to FIG. 3, the same members as those shown in FIG.
[0029]
(Example 1)
FIG. 1 shows a first embodiment in which three gas flow baffle plates 60 made of an electrically insulating material are disposed in an insulating pipe 19 in an insulating exhaust line 59 in order to reduce the conductance of the gas flow. An example is shown. The baffle plate 60 has a shape lacking a part of the disk, and is configured such that the gas flow alternately flows through the lacked part of the disk. While the gas flow flows alternately and the gas repeatedly collides with the baffle plate, the electron density in the gas decreases and the occurrence of discharge is suppressed.
[0030]
(Example 2)
FIG. 2 shows a second embodiment in which a mesh member 61 made of an insulating material is disposed in the insulating block 9 in the insulating exhaust line 59 in order to reduce the conductance of the gas flow. . In this embodiment, while the gas flow passes through the mesh member 61, the gas flow repeatedly collides with the mesh member, and the occurrence of discharge can be suppressed as in the first embodiment.
[0031]
(Example 3)
FIG. 3 shows a third embodiment according to the invention of claim 4, in which a first metal mesh 62 disposed in the back opening of the high voltage electrode and a proximity to the first metal mesh 62 are shown. An embodiment provided with a discharge prevention means comprising a second metal mesh 63 disposed on the insulating exhaust line 59 side and an insulating sheet 64 made of an electrically insulating material interposed between the two metal meshes. Show. The second metal mesh 63 is electrically grounded by, for example, a metal wire.
[0032]
The both metal meshes are not limited to meshes, but may be punching boards, or may be formed by arranging a number of metal wires horizontally. The thickness of the insulating sheet 64 made of an electrically insulating material is preferably 1 to 3 mm.
[0033]
As described above, by setting the first metal mesh 62 and the grounded second metal mesh 63 sufficiently close to each other via the insulating sheet 64, the discharge start voltage is extremely increased, It is possible to prevent discharge.
[0034]
FIG. 4 to FIG. 7 show the results of discharge experiments on the first to third embodiments and the conventional apparatus (comparative example). 4 to 7, in order to simulate the film formation state, hydrogen gas was introduced into the film formation chamber, and the pressure in the exhaust line was 27 Pa to 160 Pa (0. 6 stages in the range of 2 to 1.2 Torr), and the high frequency output was changed in 7 stages in the range of 30 to 300 W as shown on the horizontal axis in the figure to confirm the occurrence of discharge in the exhaust line The result is shown. In the figure, ◯ indicates that no discharge occurred, and x indicates that discharge occurred.
[0035]
FIG. 4 shows the discharge experiment results for the devices of Examples 1 and 2 (FIGS. 1 and 2), and FIG. 5 shows the discharge experiment results for the device of Example 3 (FIG. 3). 6 and 7 show the experimental results of the comparative example, FIG. 6 shows the discharge experimental results for the improved conventional device (FIG. 10), and FIG. 7 shows the exhaust block in the conventional device of FIG. The discharge experiment result with respect to the apparatus which made length of 9 100 mm is shown.
[0036]
As apparent from FIG. 5, in the case of the third embodiment adopting the double mesh structure related to the invention of claim 4, the exhaust line is irrelevant regardless of the film forming pressure and the high-frequency output input conditions. There is no discharge inside. On the other hand, in the case of the apparatuses of Examples 1 and 2 (FIGS. 1 and 2), as shown in FIG. 4, partial discharge occurs under the conditions of low film formation pressure and high high frequency output. As can be seen, the results are considerably improved when compared with the results of the conventional apparatus (FIGS. 7 and 8). As described above, according to the present invention, the film forming conditions are improved as compared with the conventional one, and accordingly, the mass production cost can be reduced.
[0037]
【The invention's effect】
According to this invention, as described above, it has a back surface portion parallel to the flexible substrate surface to be transported and a side wall portion having an end surface that can be hermetically contacted with the substrate, and the back surface portion has an opening. A high-voltage electrode, a ground electrode provided on the outside of the substrate facing the high-voltage electrode, having a heater for heating the substrate, and a back surface of the high-voltage electrode. An insulating exhaust line made of an electrically insulating material having a through-hole communicating with the opening of the portion in an airtight manner and having a vacuum exhaust port communicating with the through-hole, and is provided between the high voltage electrode and the substrate. A film-forming gas is introduced into the formed film-forming space, and a high-frequency voltage is applied between the high-voltage electrode and the ground electrode to generate a discharge between the substrate and the high-voltage electrode, and a thin film is formed on one surface of the substrate. Thin film photoelectric conversion device manufacturing apparatus configured to form In order to prevent discharge by reducing the conductance of the gas flow in the insulating exhaust line (for example, a plurality of gas flow baffle plates or mesh members made of an electrically insulating material) ) Is provided in the insulating exhaust line (Claims 1 to 3), or instead of a discharge preventing means for preventing discharge by reducing the conductance of the gas flow, A first metal mesh disposed in the back opening of the high voltage electrode, and a second metal mesh disposed on the insulating exhaust line side in the vicinity of the first metal mesh and electrically grounded And a discharge prevention means comprising an insulating sheet made of an electrically insulating material interposed between the two metal meshes. Even under film formation conditions where high frequency output is applied, film formation can be performed without causing discharge in the exhaust line, which can increase the throughput of the film formation system and reduce the frequency of maintenance. In particular, the mass production cost of the thin film photoelectric conversion element can be reduced.
[Brief description of the drawings]
FIG. 1 is a diagram showing a schematic configuration of an embodiment of the present invention. FIG. 2 is a diagram showing a schematic configuration of a different embodiment of the invention. FIG. 3 is a diagram showing a schematic configuration of a further different embodiment of the invention. 4 is a diagram showing discharge experiment results for the embodiment of FIGS. 1 and 2. FIG. 5 is a diagram showing discharge experiment results for the embodiment of FIG. 3. FIG. 6 is for an improved conventional thin-film photoelectric conversion device manufacturing apparatus. FIG. 7 is a diagram showing a discharge experiment result for a conventional thin-film photoelectric conversion device manufacturing apparatus. FIG. 8 is a schematic configuration diagram of a conventional thin-film photoelectric conversion device manufacturing apparatus (two-substrate parallel manufacturing method). 9 is a schematic configuration diagram of a conventional thin film photoelectric conversion element manufacturing apparatus (single substrate single-row manufacturing method). FIG. 10 is a schematic configuration diagram of a conventional thin film photoelectric conversion element manufacturing apparatus improved from FIG. ] An example of a stepping roll vacuum deposition system FIG. 12 is a plan sectional view of a conventional thin film photoelectric conversion device manufacturing apparatus. FIG. 13 is a partially enlarged view of a conventional thin film photoelectric conversion device manufacturing apparatus. Partial enlarged view of conversion element manufacturing equipment [Explanation of symbols]
DESCRIPTION OF SYMBOLS 1: Board | substrate, 9: Exhaust block, 19: Insulation piping, 21: High voltage electrode, 22: Ground electrode, 27: Shielding body, 56: Metal exhaust line, 58: Exhaust unit, 59: Insulative exhaust line, 60: Baffle plate, 61: mesh member, 62: first metal mesh, 63: second metal mesh, 64: insulating sheet.

Claims (7)

A high-voltage electrode having a back surface portion parallel to the surface of the flexible substrate to be conveyed and a side wall portion having an end surface capable of airtight contact with the substrate, and the back surface portion has an opening; A through hole provided on the outside of the substrate facing the electrode, having a heater for heating the substrate, and a back surface portion of the high voltage electrode, and in airtight communication with the opening of the back surface portion by a sealing material And an insulating exhaust line made of an electrically insulating material having a vacuum exhaust port communicating with the through hole, and for forming a film in a film forming space formed between the high voltage electrode and the substrate A thin film photoelectric conversion device configured to form a thin film on one surface of the substrate by introducing a gas and generating a discharge between the substrate and the high voltage electrode by applying a high frequency voltage between the high voltage electrode and the ground electrode. In the device manufacturing apparatus, the insulating exhaust line Of the discharge preventing means for preventing the discharge by reducing the conductance of the gas flow, apparatus for manufacturing a thin film photoelectric conversion device characterized by comprising in said insulating exhaust line. 2. The apparatus for manufacturing a thin film photoelectric conversion element according to claim 1, wherein the discharge preventing means comprises a plurality of gas flow baffle plates made of an electrically insulating material. 2. The apparatus for manufacturing a thin film photoelectric conversion element according to claim 1, wherein the discharge preventing means is a mesh member made of an electrically insulating material. 2. The first metal mesh according to claim 1, wherein the first metal mesh is disposed in the back opening of the high voltage electrode in place of the discharge preventing means for preventing discharge by reducing the conductance of the gas flow. A second metal mesh disposed on the insulating exhaust line side in the vicinity of the first metal mesh and electrically grounded, and an electrically insulating material interposed between the two metal meshes. An apparatus for manufacturing a thin-film photoelectric conversion element, comprising discharge preventing means comprising an insulating sheet. 5. The apparatus for manufacturing a thin film photoelectric conversion element according to claim 1, wherein the electrically insulating material is made of at least one of fluororesin, glass, and ceramics. . 6. The thin film photoelectric conversion device manufacturing apparatus according to claim 1, wherein the thin film photoelectric conversion device manufacturing apparatus is transported in parallel so that the thin film photoelectric conversion elements can be simultaneously manufactured on two rows of flexible substrates. Between the flexible substrates in the row, each substrate is provided corresponding to each substrate, and has a back surface portion parallel to the substrate surface and a side wall portion having an end surface capable of airtight contact with the substrate, and the back surface portion is Two high-voltage electrodes having openings, two ground electrodes provided on the outside of each of the substrates facing the high-voltage electrodes and having a heater for heating the substrates, and the two high-voltage electrodes An insulating exhaust line made of an electrically insulating material having a through-hole communicated with the opening of the rear portion in a gas-tight manner by a sealing material and having a vacuum exhaust port communicating with the through-hole. A shape between the high voltage electrode and each substrate. A film-forming gas is introduced into the film-forming space, and a high-frequency voltage is applied between the high-voltage electrode and the ground electrode to generate a discharge between the substrate and the high-voltage electrode, and a thin film is formed on one surface of each substrate. An apparatus for manufacturing a thin film photoelectric conversion element, wherein 7. A device according to claim 1, wherein a gap is formed between the substrate and the back surface portion of the high voltage electrode in parallel with the back surface portion and for flowing the film forming gas. A thermal shield for the plate-like or box-like sealing material made of a conductive material is provided over the substantially entire width of the back surface provided between the side and the side, and this shield is electrically connected to the high-voltage electrode. An apparatus for manufacturing a thin film photoelectric conversion element, wherein the film forming gas is configured to be able to flow from the gap to the opening of the back surface portion.

Images