JPH01152767A - Manufacture of thin-film solar cell - Google Patents

Abstract

PURPOSE:To eliminate the need for a metallic mask, and to reduce even the cost of a pattern material by drawing and applying a pasty complex such as clay onto substrate directly and patterning the complex through a lift-off. CONSTITUTION:A pasty complex 3 such as clay is applied onto a substrate 1 according to a desired pattern in place of the usage of a metallic mask, a thin-film is formed onto the complex 3, and the pasty complex 3 such as clay is removed, thus acquiring the desired pattern of a thin-film through a lift-off. Consequently, the accuracy of patterning is determined by line width capable of being applied by the directly drawing pasty complex such as clay, thus largely improving the accuracy. A large-area substrate incapable through a metallic mask method is also patterned easily. Patterning is conducted by the pasty complex such as clay and water, thus also reducing running cost.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method for manufacturing a thin film solar cell, characterized in that the thin film is subjected to lift-off patterning using a paste-like composite such as clay.

Prior art The conventional patterning method for this type of solar cell is shown in Fig. 6.
It was as shown in Figure 7. That is, in FIG. 6, the metal mask is brought into close contact with the substrate 1 and placed in a film forming apparatus, for example, a vacuum evaporation apparatus. In FIG. 7, after forming the transparent electrode layer 4, when the metal mask 7 is separated from the substrate 1, a pattern 8 of the transparent electrode layer 4 is formed on the substrate 1 in accordance with the window pattern of the metal mask 7. Although not shown in the figure, this process is repeated sequentially to form P and I layers of amorphous silicon.

By forming the N layer and the metal electrode layer, a solar cell is completed, and at the same time, by designing a pattern, it is possible to connect the solar cells formed on the substrate 1 in series.

Furthermore, although not shown in the drawings, the formation of solar cells and series connection were also carried out using pattern Jung method using photolithography.

Problems to be Solved by the Invention Since a metal mask is used in such conventional groove formation, the width of the p--ym for pattern line width is limited to a range that allows the creation of metal mask crosspieces. There were some problems. Therefore, it has been difficult to form a pattern line width that is less than the thickness of the metal mask. In addition, in methods that apply heat to form films, such as transparent electrode layer deposition and amorphous silicon layer deposition, thermal distortion of the metal mask causes the metal mask bars to lift off the substrate, causing the deposits to wrap around inside the core and cause the metal mask to form on the substrate. There was a problem that the metal mask pattern could not be transferred correctly. Furthermore, when using a metal mask, there is a limit to the size of the metal mask that allows the crosspieces to be held correctly in a straight line, making it impossible to increase the substrate size. Furthermore, it is necessary to prepare a metal mask for each product type and each type of film formation, which is a factor in increasing costs. Furthermore, although the method of patterning using photolithography has excellent patterning accuracy, it has the problem of high initial costs and high running costs for solar cells that aim to reduce costs.

The present invention solves these problems, and instead of using a metal mask, a paste-like composite such as clay is drawn and coated directly onto a substrate, and patterning is performed by lift-off.

Means for Solving the Problems In order to solve these problems, the present invention, instead of using a metal mask, applies a paste-like compound such as clay onto a substrate in a desired pattern. After forming a thin film thereon, the paste-like composite such as clay is removed to obtain a desired pattern of the thin film by lift-off.

Operation With this configuration, the accuracy of patterning is determined by the line width that can be applied with a paste-like compound such as clay that is directly drawn. Although the line width depends on the type of paste-like compound such as clay, it is possible to draw with a minimum line width of Om05tg+~0.3gm, and the line width accuracy using a metal mask is 0.3f.
This is significantly improved compared to f~0.5 mm (11n or more in practice). Furthermore, since the paste-like composite material such as clay adheres closely to the substrate, the pattern does not become blurred. When a metal mask is used, the limit of the patterning size is about 16α angle at most, but in the present invention, the drawing limit is determined by the size of the XY stage of the drawing device. Furthermore, since a metal mask is not required, the metal mask creation process that was required for each type of film formation is no longer necessary, and the manufacturing period can be shortened. Further, since patterning is performed using a paste-like composite such as clay and water without using chemicals such as photo-Fresist, the cost of patterning materials is also low.

EXAMPLE An example of the present invention will be described below with reference to the accompanying drawings. Fig. 1 shows a substrate 1, and in Fig. 2, a paste-like compound 3 such as clay, etc., such as alumina, montmorillonite, etc., is mixed in water and made into a gel from a nozzle 2 at an arbitrary position while moving by an XY stage. The material is extruded and applied in a band shape onto the substrate 1 in a desired pattern. Although the drawing speed at this time depends on the line width, it is possible to draw at a rate of 3ax to 1oα per second for a line width of about 60 microns and a thickness of 20 microns.

After applying a paste-like composite material such as clay to the substrate in this way, it is dried in a dryer at 160° C. for 1 hour to remove water contained in the gel. Montmorillonite contains water of crystallization, but interlayer water is released at 120°C. Crystal water is
Since it is not emitted up to 690℃, it can be used at relatively low temperatures (1so℃~sso℃) like amorphous silicon solar cells.
) The various thin films formed will not be affected by moisture contained in paste-like composites such as clay if they are dried at about 180'C. Also, although not shown in the figure, by applying a paste-like compound such as clay directly to the substrate, the metal mask is separated from the substrate by heat etc., and the vapor deposits enter the inside of the metal mask and stick to the substrate. The blur was completely eliminated. In FIG. 3, after drying, the transparent electrode layer 4
In order to form a transparent electrode layer 4, the transparent electrode layer 4 is formed by electron beam evaporation. The transparent electrode layer 4 is uniformly deposited on the substrate 1 and the paste-like composite material 3 such as clay. As shown in FIG. 4, after forming the transparent electrode layer 4, the substrate 1 is placed in water and washed with high-pressure water, a brush, etc., resulting in a paste-like composite 3 such as clay (a mixture of alumina and montmorillonite).
will gel again and be dispersed in water. As a result, the transparent electrode layer 4 formed on the base-like composite 3 such as clay is also peeled off at the same time, and the pattern 8 is completed by lift-off of the transparent electrode layer 4. In the cross-sectional view of FIG. 5, although not repeated in the figure, an amorphous silicon layer 6. The metal electrode layer 6 was patterned and formed using the same procedure.

This is a typical series connection diagram of solar cells.

Effects of the Invention As described above, according to the present invention, the minimum line width is smaller than when a metal mask is used, and the area required for inter-film wiring can be reduced. Since the wiring part does not contribute to photoelectric conversion, in the method using a metal mask, the minimum line width is large and the ineffective area for photoelectric conversion accounts for approximately 20% or more of the photoelectric conversion device. However, in the present invention, patterning is performed. For photoelectric conversion devices, it is about 10%.

With this improvement, the ineffective area due to wiring is reduced, and the power generation efficiency of the solar cell is improved by about 10% in the same area. Also, mask blur due to thermal distortion of the mask is no longer present. In addition, it is easy to change the product type, and it is also easy to pattern large-area substrates, which is impossible with the metal mask method. Furthermore, since patterning is performed using a paste-like composite material such as clay and water, the cleaning cost is also low. This patterning method is roll-to-roll.
It can also be used as a patterning method when sequentially depositing various thin films with a roll.

As described above, the present invention has many advantages in terms of the solar cell formation process and industrialization.

[Brief explanation of the drawing]

Fig. 1 is a perspective view of a substrate in an embodiment of the solar cell manufacturing method of the present invention, and Fig. 2 is a diagram showing the process order in an embodiment of the solar cell manufacturing method of the present invention, in which paste of clay or the like is applied to the substrate. Fig. 3 is a perspective view of applying a paste-like composite such as clay, and Fig. 3 is a diagram showing the process order in an embodiment of the solar cell manufacturing method of the present invention.After coating a paste-like composite such as clay on a substrate and drying, FIG. 4 is a perspective view showing the process of depositing a transparent electrode layer, and FIG. FIG. 6 is a perspective view showing a peeled-off transparent electrode layer on a transparent electrode layer on a substrate, and FIG. ,
Figure 6 showing sequential patterning and deposition of metal electrode layers.
The figure is a perspective view of a substrate and a metal mask overlaid using a conventional patterning method using a metal mask. Figure 7 shows a transparent electrode layer formed on a substrate using a conventional patterning method using a metal mask, and then a metal mask is applied. It is a removed perspective view. 1... Board, 2... Nozzle, 3...
... Paste composite such as clay, 4 ... Transparent electrode layer, 6 ... Amorphous silicon layer, 6.
...metal electrode layer, 7...metal mask,
8... Pattern. Name of agent: Patent attorney Toshio Nakao and 1 other person/
-m-Substrate 3- Adhesive paste-like composite composition Figure 1! Figure 2 Figure 1 - Basic figure 6

Claims (1)

[Claims] After direct drawing by discharging a paste-like compound such as clay onto a substrate, a thin film is formed on the substrate, and then the paste-like compound such as clay is removed to perform lift-off patterning on a desired portion of the thin film. A method for manufacturing a thin film solar cell characterized by: