JPS6350073A - Manufacture of thin film solar battery - Google Patents

Abstract

PURPOSE:To reduce the number of processes to make, the use of a resist unnecessary, and to make the manufacture of a battery having a large area possible, by using conductive paste in which carbon particles are used as a conductive materiel. CONSTITUTION:On one side of a glass substrate 1, a transparent conductive film 20 made of transparent conductive material is coated, on which laser light is radiated for patterning, on which film a P-type layer, an I-type layer and an N-type layer are constituted in order and an a Si film 30 is formed, from which the pattern of an a-Si film region 3 is drawn. A metal film 40 is formed on the whole surface. On a portion of the film 40 to be left as a pattern, cellulose system conductive paste 5 containing carbon particles as a conductive material is printed. After heating and drying, the exposed part of the film 40 is subjected to etching, and patterning for a metal electrode 4 is performed. Thereby, an a-Si solar battery having a large area is obtained.

Description

[Detailed description of the invention] [Technical field to which the invention pertains]

The present invention provides a metal film in which a plurality of transparent electrodes provided on a light-transmitting insulating substrate are coated on the entire surface with metal electrodes facing each other through a semiconductor thin film made of amorphous silicon (hereinafter referred to as a-3t) or the like. The present invention relates to a method for manufacturing a thin film solar cell formed by patterning by selectively removing .

[Prior art and its problems]

Solar cells that use amorphous silicon (hereinafter referred to as a-5t) produced by a silane gas glow discharge method as a semiconductor thin film material are manufactured using a gas phase method, so they can be easily made into large areas and are necessary for solar cells. The film thickness is as thin as 1p, and the temperature at the time of generation is only 200°C to 300°C, so it is recommended to use a transparent insulating film made of glass or an organic material (for example, polyester, polyimide film, etc.) for the substrate. It is attracting attention as a solar cell with the potential to reduce costs. a using a glass substrate
-3t solar cells have a large area, and as shown in FIG.
i-membrane 3. The metal electrodes 4 are stacked, and the edge of the metal electrode 4 overlaps the edge of the transparent electrode 2, so that a cross-sectional structure in which unit cells are connected in series is obtained. Therefore, large area a −5i
In order to manufacture solar cells, transparent electrodes 2. a-5i membrane 3
．． It is necessary to pattern the metal electrode 4 in accordance with the process. At the beginning of the development of A-3T solar cells, a selective film formation method using a metal plate mask was used for this patterning method, but because it was not possible to form fine patterns, the power generation area relative to the total substrate area was low, and the output of the solar cell was low. was causing a decline in In order to solve this problem, we have developed a method of chemically etching using a mask pattern using a printed resist, and a chemical etching method using a mask pattern using a photosensitive resist used in ICs etc. to improve area efficiency. A method of etching and patterning is used. according to this,
While the area efficiency is about 75% when a metal plate mask is used, it becomes about 90%, and the output is improved by about 20%. However, as the area of solar cells increases, the incidence of defects such as pinholes and pattern defects increases, which lowers the manufacturing yield of solar cells and increases prices. In order to eliminate this drawback, a method has recently been developed in which the thin film is removed by irradiation with powerful energy such as a laser. According to this method, there is no need to apply printing resist or photosensitive resist to the film, and the thin film can be patterned directly, so there is no need for material costs.
This method is attracting attention as a method of manufacturing solar cells because of the simplicity of the process. However, at present, patterning methods using lasers and the like have only been established for transparent electrodes and a-3T films, and the only technology to pattern metal electrodes without reducing the output of the solar cell is to adjust the laser output. Because it is difficult to
It has not been put into practical use yet. Therefore, conventional methods are used for patterning metal electrodes, which hinders cost reduction. That is, in this case, it is necessary to form a resist for pattern formation on the metal film, remove the portions to be separated by chemical etching, etc., and then peel off the resist.

[Purpose of the invention]

The present invention forms a mask on a metal film deposited on the entire surface,
The present invention aims to simplify the process of selectively removing portions not covered by a mask, and to provide a method for manufacturing a low-cost, large-area thin-film solar cell.

[Key points of the invention]

In the present invention, when patterning a metal film to form a metal electrode, a mask pattern is formed by printing a conductive paste, and then the unmasked area is removed by a chemical etching method to make carbon particles conductive. Since the conductive paste mask used as the material does not need to be removed, the above objective is achieved.

[Embodiments of the invention]

FIG. 1 shows a large area a manufactured by an embodiment of the present invention.
The cross-sectional structure of a -3t solar cell is shown, and parts common to those in FIG. 2 are given the same reference numerals. Such a solar cell is manufactured by the steps shown in FIG. 3+8) to (gl). As shown in FIG. ) by vacuum evaporation, sputtering, or thermal CVD of tin oxide.
After depositing a transparent conductive film 20 formed by D (chemical vapor phase method), the transparent electrode 2 is patterned as shown in FIG. 3(b) by irradiating strong energy such as a laser beam. Then, as shown in FIG. 3(Q), a p-type layer, an i-type layer, and an n-type layer are sequentially formed on the entire surface of the substrate using a plasma glow discharge method to form an a-3t film 30. Subsequently, the a-3t film t+I region 3 is patterned as shown in FIG. 3(d) using the same method used to pattern the transparent electrode 2 from the a-3t film 30. Then, a metal film 40 made of aluminum and having a thickness of 5000 mm is formed over the entire surface by vacuum evaporation or sputtering. A cellulose-based conductive paste 5 containing carbon particles as a conductive material is printed at a thickness of 10 μm using a screen printing method or the like on the area to be left as a pattern on the metal film 40 formed on the entire surface, as shown in FIG. 3 (fl). After heating and drying, the exposed parts of the metal film 4o are etched with an existing aluminum corrosive solution such as phosphonitric acid or diluted nitric acid, and patterned into the metal electrode 4 as shown in FIG. 3 ((a)). The large-area a-3t solar cell shown in FIG. 1 is fabricated by the steps shown in FIG. 1. Conventionally, the conductive paste 5 is not used in the step shown in FIG. Patterning was carried out, but after etching, it was necessary to remove and clean the printed resist or photosensitive resist.Also, the resist that was used, especially the photosensitive resist, was not only for the price, but also for the purpose of peeling. It is necessary to use special chemicals.In comparison, by using conductive paste 5 made of carbon particles as a conductive material, the material itself is not so expensive, and there is no need to peel it off after patterning, and it can be used as an electrode as it is. This has the advantage of reducing the number of steps.

【Effect of the invention】

According to the present invention, when patterning a metal electrode by selective etching, by using a conductive paste containing carbon particles as a conductive material that is not corroded by an etching agent as a mask material, the mask can be peeled off after patterning.
Since there is no need for cleaning, the number of steps is reduced, and there is no need to use expensive resists, making it possible to manufacture large-area thin-film solar cells at low cost.

[Brief explanation of the drawing]

FIG. 1 is a partial cross-sectional view of a solar cell according to an embodiment of the present invention, FIG. 2 is a partial cross-sectional view of a solar cell according to a conventional manufacturing method, and FIG. 3 sequentially shows the manufacturing process of the solar cell shown in FIG. 1. FIG. 1 glass substrate, 2: transparent electrode, 3: a-3i film, 4
: Metal electrode, 40: Metal film, 5: Conductive paste I.

Claims (1)

[Claims] 1) A metal electrode that faces a plurality of transparent electrodes provided on a light-transmitting insulating substrate with a semiconductor thin film interposed therebetween is partially covered with a mask, and the areas not covered with the mask are chemically etched. 1. A method for manufacturing a thin film solar cell, which comprises forming a mask pattern by printing a conductive paste when forming the mask pattern by selectively removing it.