JP2000183380A - Method and apparatus for film-formation of solar cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and apparatus for film-forming of a solar cell, wherein a required fin-film is sequentially formed by having a substrate to be reciprocally transferred between a supply roll and a take-up roll of a roll-to- roll method, etc., before going through a film-forming chamber. SOLUTION: This film-forming apparatus, wherein a long substrate taken-up with a vacuum film-forming method is supplied, a film-forming chamber 5 for forming a thin-film constituting a optoelectric conversion layer of a thin-film solar cell on the substrate is provided, and the substrate is taken up after film- formation. Here, the substrate is reciprocally transferred between a supply roll and take-up roll, a thin-film is formed on the substrate in every forward and backward run for less number of film-forming chambers 5 even if it is a multi-layer, thus a large-area solar cell is efficiently manufactured with no increase in film-forming device size.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus and a method for forming a thin-film solar cell in which a photoelectric conversion layer mainly composed of a photoelectric conversion material is formed on a flexible substrate such as a substrate. .

[0002]

2. Description of the Related Art As a typical example of a thin film semiconductor device having a plurality of electrode layers and semiconductor layers, a semiconductor layer mainly composed of amorphous silicon (hereinafter referred to as a-Si) is used as a photoelectric conversion layer. There is a large-area thin-film solar cell having a structure sandwiching layers. As a method for manufacturing such a large-area thin-film solar cell, there is a roll-to-roll method or a stepping roll method, which is superior in productivity to a single-wafer method. While sequentially sending a flexible or flexible substrate made of a long polymer material or a metal material such as stainless steel wound on a roll to each film forming chamber,
In this method, a thin-film solar cell is manufactured by forming layers such as a photoelectric conversion layer and an electrode layer on a substrate for each deposition chamber. The former forms a film on a substrate that moves continuously in each film forming chamber, and the latter forms a film on a substrate stopped in each film forming chamber at the same time. Has been sent to The stepping roll type film forming apparatus is excellent in that the characteristics of each thin film can be stably obtained since gas mutual diffusion between adjacent film forming chambers can be prevented.

[0003]

For example, a film forming apparatus (not shown) of a stepping roll system and a roll-to-roll system is constituted by a plurality of film forming chambers, and a substrate fed from a feed roll is provided with a plurality of film forming chambers. , A thin film unique to each film forming chamber is formed, laminated, and taken up by a take-up roll. Even when the photoelectric conversion layer formed here is made of only a-Si, three film forming chambers corresponding to the p layer, the i layer, and the n layer are required. Requires more film forming chambers. Roll Even in the stepping roll type or roll-to-roll type film forming apparatus which is excellent in productivity, there is a problem that it is not possible to increase the productivity by increasing the length of the substrate. Therefore, in the present invention, it is not necessary to provide a large number of film forming chambers according to the number of thin films, and the substrate is reciprocated between an unwinding roll and a take-up roll, and the necessary thin films are sequentially passed through the film forming chamber. It is an object to provide a solar cell film forming apparatus and a solar cell film forming method capable of forming a film.

[Means for Solving the Problems]

According to the first aspect of the present invention, there is provided a film forming chamber for feeding a long substrate wound by a vacuum film forming method and forming a thin film constituting a photoelectric conversion layer of a thin film solar cell on the substrate. A film forming apparatus for winding the substrate after film formation, wherein the substrate is reciprocated between an unwinding roll and a winding roll, and a thin film is formed on the substrate in each of a forward path and a return path. It is a solar cell film forming apparatus.

According to a second aspect of the present invention, in the solar cell film forming apparatus according to the first aspect, there are provided two or more film forming chambers, and at least one chamber has a substrate cleaning mechanism and a pretreatment mechanism. And

[0006] The invention described in claim 3 is claim 1 or 2.
The solar cell film forming apparatus described above further includes a cleaning mechanism for removing impurities in the film forming chamber before and after film formation.

According to a fourth aspect of the present invention, in the solar cell film forming apparatus according to the first to third aspects, the vacuum film forming method is a plasma chemical vapor deposition method.

According to a fifth aspect of the present invention, there is provided a solar cell film forming apparatus having a film forming chamber having a mechanism for generating plasma, wherein the frequency of generating the plasma is 20 to 200 MHz.

According to a sixth aspect of the present invention, in the solar cell film forming method using the solar cell film forming apparatus according to any one of the first to fourth aspects, the long substrate wound on a roll is sent out to a film forming chamber, and Forming a thin film constituting a photoelectric conversion layer of a thin-film solar cell on a substrate and winding the film on a roll; and sending the substrate from the roll to a film forming chamber to form a thin film on the substrate, and winding the film on a roll. A solar cell film forming method characterized by forming a photoelectric conversion portion of a thin-film solar cell by appropriately repeating a returning step to be taken.

According to a seventh aspect of the present invention, in the method of forming a solar cell according to the sixth aspect, a thin film formed on the substrate is different for each process.

According to an eighth aspect of the present invention, in the method of forming a solar cell according to the sixth aspect, a plurality of different thin films are sequentially formed on the substrate in one step.

According to a ninth aspect of the present invention, in the solar cell film forming method according to the sixth to eighth aspects, the thin film is formed by a plasma enhanced chemical vapor deposition method.

According to a tenth aspect of the present invention, there is provided a method for forming a solar cell, wherein the frequency of generation of plasma in the film forming chamber is 20 to 200 MHz.

[0014]

FIG. 1 is a schematic sectional view of a solar cell film forming apparatus 10 according to an embodiment of the present invention.

The solar cell film forming apparatus 10 includes an unwinding chamber 1 for storing an unwinding roll 11, a winding chamber 8 for storing a winding roll 12, and a pressure partition for maintaining an airtight state in each processing means in a film forming process. And a differential evacuation chamber, which is a space formed by the pressure barrier, a pretreatment chamber 4 for pretreating the substrate 13, an electrode 7 for forming a film by a vacuum evaporation method, and a film formation chamber 5 having a power source 6 thereof. An exhaust pump 9 for making the system vacuum. The supply of the thin film material to be formed and the control system thereof are omitted.

The solar cell film forming apparatus 10 can form a photoelectric conversion layer (PIN or NIP) of a solar cell with a simple configuration. The length of the vacuum formation may be determined in accordance with the layer that needs to have the largest film thickness in the three-layer configuration. Since the P layer or the N layer is thinner than the I layer, it may be controlled by the deposition rate or the number and area of the electrodes.
Further, in order to heat the substrate, a method in which the substrate is held in a cooling can and a method in which the substrate is moved straight in a plasma space is preferable.

The cleaning of the substrate 13 by the pre-processing chamber 4 refers to the removal of oil or water from a metal or a transparent conductive substrate manufacturing process as much as possible for humans or electrodes, and removal of the oil and water to form a uniform surface on the substrate. It is intended to be a film.
Further, the surface is roughened or active points are forcibly formed to improve the adhesion of the first layer of the photoelectric conversion layer. Moisture or the like present on the substrate or in the substrate has a high possibility of deteriorating the performance of the photoelectric conversion layer and the like, and should be avoided.

In the solar cell film forming apparatus of the present invention, particularly, the apparatus 10 of FIG. 1, P, I, and N layers are sequentially formed in the same film forming chamber. A dopant-forming material such as diborane and phosphine must be added, and impurities such as the dopant-forming material hinder the formation of the I layer. Therefore, the inside of the tank is cleaned between each layer formation by using an appropriate etchant.

In the present invention, although it is not particularly mentioned, it is assumed that the thin film material to be formed is not formed by thermal decomposition. The reason is that a heater used for thermal decomposition into the substrate 13 made of a polymer resin film or the like has a large influence.

As for the discharge frequency during film formation by plasma enhanced chemical vapor deposition, a higher frequency is more advantageous for film formation, and a higher frequency than the commercial frequency of 13 MHz is more advantageous. However, there is an upper limit for the transfer of high frequency through a cable, and it is considered that the upper limit is about 200 MHz.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described in detail. The solar cell film forming apparatus of the present invention shown in FIG. 1 has a thickness of 20 to 200 μm with a metal or a transparent conductive film from the unwinding chamber 1.
A long substrate 13 (unwinding roll 11) of a polymer resin film such as a polyethylene terephthalate or polyimide film having a width of 0.2 to 1.0 m is supplied, and adheres to the substrate 13 in the pretreatment chamber 4. Then, impurities such as moisture generated from the substrate 13 are removed using a means such as ultrasonic waves, and a film serving as a nucleus for forming a photoelectric conversion layer (not shown) is formed over the substrate 13.

The substrate 13 is sent to the film forming chamber 5 to select an arbitrary value of a plasma frequency of 20 to 200 MHz to generate plasma and to supply silane, which is a raw material gas for a thin film, supplied to the film forming chamber 5. Decomposes phosphine, substrate 1
3 on the N layer by plasma enhanced chemical vapor deposition (plasma CVD)
Method). The substrate 13 on which the N layer was formed was wound up in the winding chamber 8 to form a winding roll 12.
Further, carbon trifluoride is introduced into the film forming chamber 5 as an etchant, and the inside of the chamber is sufficiently cleaned.

Next, the substrate 13 taken up by the take-up roll 12 in the previous step is unwound in the reverse direction and sent to the film forming chamber 5.
Similarly, an arbitrary value of a plasma frequency of 20 to 200 MHz is selected, plasma is generated, and silane, hydrogen, and the like, which are source gases of a thin film supplied into the film forming chamber 5, are decomposed, and the I layer is formed by a plasma CVD method. Were laminated. The substrate 13 on which the I layer was formed on the N layer in this manner was wound up in the unwinding chamber 1 to obtain an unwinding roll 11. Further, the inside of the film forming chamber 5 was cleaned in the same manner as in the previous step, and was sent out from the unwinding roll 11 of the unwinding chamber 1 to the film forming chamber 5, and a P layer was formed on the I layer in the same manner. The formation of the photoelectric conversion layer (not shown) laminated on the substrate 13 in the order of these NIPs is completed.

The order of the film formation can also be determined according to the configuration of the photoelectric conversion layer to be formed. In this embodiment, the formation of the PIN type photoelectric conversion layer in which the film formation order of the N layer and the P layer is exchanged is also possible. As a result, a good film was obtained.

In the embodiment, only one film forming chamber 5 is provided, but two or more film forming chambers 5 may be provided if necessary.

[0026]

According to the present invention, in forming a thin film semiconductor device having a plurality of semiconductor layers, a film is formed between an unwinding roll and a take-up roll by a film-forming apparatus and a film-forming method such as a roll-to-roll method. By transporting the room back and forth,
Since the number of film forming chambers can be reduced, the size of a film forming apparatus does not increase, and a large-area solar cell can be efficiently manufactured. Further, by using a plasma frequency of 20 to 200 MHz in the film formation process by the plasma chemical vapor deposition method, it is possible to perform film deposition on the substrate at a high speed.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a solar cell film forming apparatus 10 according to an embodiment of the present invention.

[Explanation of symbols]

 1 unwinding chamber 2 pressure bulkhead 3 differential exhaust chamber 4 pretreatment chamber 5 film forming chamber 6 power supply 7 electrode 8 winding chamber 9 exhaust pump 10 solar cell film forming apparatus 11 unwinding roll 12 winding roll 13 substrate

Continuing on the front page (72) Inventor, Rei Shirai 1-5-1, Taito, Taito-ku, Tokyo Letterpress Printing Co., Ltd. (72) Inventor Shiro Shibata 1-5-1, Taito, Taito-ku, Tokyo Letterpress printing shares In-house (72) Inventor Kyo Yamamoto 1-5-1, Taito, Taito-ku, Tokyo Letterpress Printing Co., Ltd.F-term (reference) 4K030 AA06 AA08 AA17 BA29 CA07 CA12 DA03 FA01 GA12 HA04 JA18 KA14 LA16 5F045 AA08 AB04 AC01 AF10 CA13 DP22 EB02 EB06 EN01 5F051 BA14 CA15 CA21 DA04 GA05

Claims (10)

[Claims] An elongate substrate wound up by a vacuum film formation method, and a film formation chamber for forming a thin film constituting a photoelectric conversion layer of a thin film solar cell on the substrate; What is claimed is: 1. A film forming apparatus for winding a substrate, wherein the substrate is reciprocated between an unwinding roll and a winding roll, and a thin film is formed on the substrate in a forward path and a return path, respectively. apparatus. 2. The apparatus according to claim 2, wherein said film forming chamber has at least two chambers, and
The solar cell film forming apparatus according to claim 1, wherein the chamber has a substrate cleaning mechanism and / or a pretreatment mechanism. 3. The solar cell film forming apparatus according to claim 1, further comprising a cleaning mechanism for removing impurities in the film forming chamber before and after the film forming. 4. The solar cell film forming apparatus according to claim 1, wherein said vacuum film forming method is a plasma chemical vapor deposition method. 5. A solar cell film forming apparatus, comprising: a film forming chamber having a mechanism for generating plasma; wherein the frequency of generating the plasma is 20 to 200 MHz. 6. A solar cell film forming method using a solar cell film forming apparatus according to claim 1, wherein a long substrate wound on a roll is sent out to a film forming chamber, and a thin film solar cell is placed on the substrate. A forward pass step of forming a thin film constituting the photoelectric conversion layer of the above and winding the roll onto a roll, and a return pass step of sending the substrate from the roll to a film forming chamber, forming a thin film on the substrate, and winding the roll onto a roll, as appropriate. Forming a photoelectric conversion part of a thin-film solar cell. 7. The method according to claim 6, wherein a different thin film is formed on the substrate for each process. 8. The method according to claim 6, wherein a plurality of different thin films are sequentially formed on the substrate in one step. 9. The method for forming a solar cell according to claim 6, wherein the method for forming the thin film is a plasma enhanced chemical vapor deposition method. 10. A solar cell film forming method, wherein a plasma generation frequency in a film forming chamber is 20 to 200 MHz.