JP2001119048A - Manufacturing method of integrated thin film solar cell - Google Patents

Abstract

(57) [Problem] To manufacture an integrated thin-film solar cell capable of maintaining high pattern processing accuracy and obtaining a high processing speed as compared with a laser scribe method even when a substrate has a large area. Provide a way. SOLUTION: In a method of manufacturing an integrated thin-film solar cell in which a plurality of solar cells made of an amorphous silicon-based semiconductor are connected in series on a transparent insulating substrate, an electrode made of a metal thin film is deposited on the amorphous silicon-based semiconductor. Forming and mechanically dividing and patterning the deposited electrode by mechanical cutting means.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing an integrated thin-film solar cell, and more particularly, to an integrated method in which a plurality of solar cells made of an amorphous silicon semiconductor are connected in series on a transparent insulating substrate. The present invention relates to a method for patterning electrodes in a method for manufacturing a thin-film solar cell.

[0002]

2. Description of the Related Art FIG. 5 is a sectional view schematically showing the structure of an example of a conventional integrated thin-film solar cell.

Referring to FIG. 5, this integrated thin-film solar cell has a transparent electrode layer 6, an amorphous photoelectric conversion layer 7, and a back electrode layer 8 laminated on one surface of a transparent insulating substrate 5 such as glass. It has a plurality of unit cells having a structure.

The amorphous photoelectric conversion layer 7 in each unit cell
Is formed by laminating N-type, I-type and P-type amorphous silicon layers, and generates an electromotive force upon receiving sunlight. Adjacent unit cells are electrically connected in series, and the electromotive force obtained by adding the electromotive force of each unit cell becomes the output voltage as a whole.

When fabricating an integrated thin-film solar cell constructed as described above, each of the thin-film layers 6, 7, 8 laminated on a substrate is used.
It is necessary to form a groove (hereinafter referred to as a “scribe groove”) in each of the thin film layers 6, 7, and 8 by patterning in order to divide the film into strips in association with individual unit cells.

As a method of pattern processing, laser scribing, in which a thin film is irradiated with laser light to evaporate a part of the thin film, is widely used because it is suitable for fine processing. This laser scribe processing includes not only sublimation of the material due to local heating but also ablation (peeling) due to a shock wave.

That is, first, after a transparent electrode layer 6 is laminated on the back surface of the transparent insulating substrate 5, the transparent electrode layer 6 is irradiated with a laser beam to form a line on the surface of the transparent electrode layer 6 at a constant pitch. The first scribe groove S is scanned at the scanned position.
Form L1. Thereby, the transparent electrode layer 6 is divided into a plurality of strips, and each transparent electrode layer 6 is electrically insulated from each other.

Next, an amorphous photoelectric conversion layer 7 is laminated thereon by, for example, plasma CVD (chemical vapor deposition). Then, the amorphous photoelectric conversion layer 7 is irradiated with laser light, and the surface of the amorphous photoelectric conversion layer 7 is scanned at the same pitch as the above-mentioned pitch, and the second photoelectric conversion layer 7 is moved to a position not overlapping with the first scribe groove SL1. A scribe groove SL2 is formed. Thus, the amorphous photoelectric conversion layer 7 is divided into a plurality of strips, and each amorphous photoelectric conversion layer 7 is electrically insulated from each other.

Next, after laminating the back electrode layer 8 thereon, the back electrode layer 8 is irradiated with laser light to scan the surface of the back electrode layer 8 in a line at the same pitch as the above pitch. And the third scribe groove at a position not overlapping with the second scribe groove SL2.
A scribe groove SL3 is formed. As a result, the back electrode layer 8 is divided into a plurality of parts, each back electrode layer 8 is electrically insulated from each other, and the back electrode layer 8
And the transparent electrode layer 6 of the adjacent unit cell immediately below it are electrically connected through the second scribe groove SL2.

As described above, when the integrated thin-film solar cell is manufactured by using the laser scribe method, compared with the case of using a pattern processing method using another photoresist,
The scribe groove can be formed relatively easily. As a result, the manufacturing process can be simplified.

In addition to the laser scribe method, a mechanical scribe method for mechanically forming scribe grooves other than the resist patterning method is known as a method for integrating solar cells using other semiconductor materials.

For example, Japanese Patent Application Laid-Open No. Hei 10-200142 discloses a solar cell using a CIS-based semiconductor material.
A method of forming a scribe groove in an S semiconductor layer with an end mill rotating at a high speed is disclosed. This publication also discloses a mechanical scribe method of a CIS film using a blade as a prior art.

However, application of a solar cell using an amorphous silicon semiconductor, division of a back electrode of a semiconductor layer,
No application to patterning is disclosed at all, and it is unknown at all whether the mechanical scribe method can be applied to separation and patterning of the back electrode of a solar cell using a thin-film amorphous silicon-based semiconductor.

[0014]

When patterning is performed by the conventional laser scribing method, it is necessary to narrow the laser beam very finely. However, when the substrate is bent or distorted, the processed surface has a focal depth of laser light. There is a problem that the beam spreads out from the inside, the laser beam irradiation energy density on the processing surface decreases, and it becomes impossible to form a pattern with high accuracy. In particular, when the substrate has a large area, the flatness is likely to be reduced, and the scribe pattern may be partially connected without disconnection, thereby causing a short circuit between cells of the unit.

Further, the laser scribe method has a problem that the processing speed is slow because the number of laser beams that can be simultaneously applied to the processing surface is one or several.

On the other hand, when the mechanical scribe method is applied to a solar cell using an amorphous silicon-based semiconductor, the amorphous silicon film is very hard, and at most 300 nm at most. It was very difficult to pattern, and it was considered difficult to apply the technology disclosed in CIS.

An object of the present invention is to solve the above-mentioned problems,
An object of the present invention is to provide a method of manufacturing an integrated thin-film solar cell capable of maintaining high pattern processing accuracy even when a substrate has a large area and obtaining a higher processing speed as compared with a laser scribe method.

[0018]

According to a first aspect of the present invention, there is provided a method of manufacturing an integrated thin-film solar cell, wherein a plurality of solar cells made of an amorphous silicon-based semiconductor are connected in series on a transparent insulating substrate. A method for manufacturing a solar cell, comprising: depositing and forming an electrode made of a metal thin film on an amorphous silicon-based semiconductor; and mechanically dividing and depositing the deposited electrode by mechanical cutting means. Features.

In the present specification, "mechanical cutting means"
Is a means to mechanically cut the electrode or resist,
Specifically, a cutting tool such as a blade-shaped cutting tool, a cutting tool, and an end mill is used.

According to a second aspect of the present invention, there is provided a method of manufacturing an integrated thin-film solar cell in which a plurality of solar cells made of an amorphous silicon-based semiconductor are connected in series on a transparent insulating substrate. Depositing and forming an electrode made of a metal thin film on an amorphous silicon-based semiconductor, applying a resist on the deposited electrode, and mechanically dividing the applied resist by mechanical cutting means. Patterning; and etching and etching the electrode from the patterned resist to divide and pattern the electrode.

According to a third aspect of the present invention, in the method of the first or second aspect, the step of patterning the electrode or the resist is such that the electrode or the resist is completely divided. And, while applying pressure in a range where the amorphous silicon-based semiconductor is not completely divided, the mechanical cutting means is moved,
It is characterized by cutting and patterning.

In the present invention, the pressure applied to the mechanical cutting means is adjusted so that the electrode or resist is cut and the amorphous silicon-based semiconductor thin film is not cut. If the pressure is low, the electrode or resist to be patterned will be incompletely cut, while if the pressure is too high, the semiconductor thin film will be cut and the opposite surface electrode will be exposed. However, since the hardness of amorphous silicon is so high that it can be used for a photosensitive drum of a copying machine in which the surface is rubbed with a large amount of paper or a cleaning blade, by maintaining the contact pressure between the mechanical cutting means and the surface to be processed within a certain range. Only an electrode made of a metal thin film of Al or Ag having a relatively low hardness or a resist made of resin can be cut and patterned.

According to a fourth aspect of the present invention, there is provided a method of manufacturing an integrated type thin film solar cell according to any one of the first to third aspects, wherein a plurality of mechanical cutting means are arranged at regular intervals. By mechanically moving the mechanical cutting means and the electrode or the resist relatively, the electrode or the resist is mechanically cut at a constant interval and patterned.

According to a fifth aspect of the present invention, there is provided a method of manufacturing an integrated type thin film solar cell according to any one of the first to third aspects, wherein the mechanical cutting and patterning by the mechanical cutting means is performed by: The method is characterized in that after patterning is performed on the electrode by a laser beam, the patterning is performed on a portion where patterning is defective.

According to a sixth aspect of the present invention, in the method of manufacturing an integrated thin-film solar cell according to any one of the first to fifth aspects, the width of the mechanical cutting by the mechanical cutting means is zero. 0.03 to 0.3 mm.

The “cut width” refers to the width of the connection groove of the electrode after cutting. In the present invention, the cutting width by the mechanical cutting means is preferably 0.01 mm to 1 m.
m, more preferably in the range of 0.03 mm to 0.3 mm.

By setting the content within such a range, an integrated thin-film solar cell having good characteristics can be manufactured. That is, when the cutting width is 0.03 mm or less, particularly 0.01 mm or less, the resistance of the semiconductor film between the adjacent back electrodes decreases, and the characteristics of the integrated thin-film solar cell deteriorate. On the other hand, when the cutting width is 0.3 mm or more, particularly 1 mm or more, the cutting groove is too wide, the effective power generation area is reduced, and the semiconductor thin film under the cutting groove is easily damaged.

[0028]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic view of an example of a manufacturing apparatus capable of implementing an integrated thin-film solar cell manufacturing method according to the present invention.

Referring to FIG. 1, on the surface of glass substrate 5, a photoelectric conversion layer and a back electrode 8 are laminated.
The blade-shaped cutting means 1 is movably installed at a predetermined position by means of a moving means 3 in the X and Y directions such as a linear motion rail provided on a fixed base, and a pressure applying means 2 such as a spring or a weight. As a result, the back electrode 8 is mechanically cut by being moved by XY-direction driving means (not shown) while applying a certain range of pressure to the back electrode 8.
Perform patterning. In this way, the mechanical cutting groove 13 is formed on the surface of the back electrode 8 by the blade-shaped cutting means 1.

After the blade-shaped cutting means 1 is moved in the X direction to form one mechanical cutting groove 14, the blade-shaped cutting means 1 is moved in the Y direction until the next mechanical cutting groove formation start position. In this case, the pressure applying means 2 rises greatly, and the blade-shaped cutting means 1 is separated from the back electrode 8 so as not to damage the surface of the back electrode 8.

(Embodiment 1) An example of a method for manufacturing an integrated thin-film solar cell according to the present invention will be described below with reference to FIGS.

FIG. 2 is a sectional view of an integrated structure for dividing cells on a substrate and connecting them in series in the method of manufacturing an integrated thin-film solar cell according to the present invention. The same is true.

FIG. 3 is a plan view of the solar cell shown in FIG. 2 as viewed from the back electrode side. Referring to FIG. 3, in this integrated thin-film solar cell, a power generation region is divided by scribe lines 14. However, the substrate peripheral portion 15 is electrically separated from the power generation region by the trimming line, and it is not necessary to divide for integration and scribe for serialization. However, the basic cutting and patterning according to the present invention can be applied to the formation of this trimming line.

Referring to FIG. 2, a glass substrate 5 on which a transparent conductive film 6 is formed in advance is used. This glass substrate 5 has S
A transparent conductive film 6 made of nO ₂ is formed on one surface of the glass substrate 5 and the entire peripheral end surface.

Next, the transparent conductive film 6 is patterned by using a laser. That is, the first opening 11 is formed by separating the transparent conductive film 6 into a strip shape.

Subsequently, the substrate 5 is washed with pure water, and the photoelectric conversion layer 7 is formed by a known plasma CVD method. The photoelectric conversion layer 7 has a three-layer structure of a thin film of amorphous silicon.
It is composed of an Hp layer, a Hi layer, and a Hn layer, and has a total thickness of 100.
nm to 600 nm.

Next, similarly to the first opening 11, the second opening 12 is formed by using a laser. The second opening 12 is
100 μm from a place that approximately overlaps the first opening 11 by about half
Form at a distance.

Subsequently, a back electrode 8 is formed by a known sputtering method. As the material of the back electrode 8, Ag, which is a metal having high reflectance, is used. The thickness is about 100 nm to 1 μm. In this embodiment, the back electrode 8 is a single layer for simplicity, but a transparent conductive film such as ZnO may be formed on the photoelectric conversion layer 7 in order to use reflected light effectively. .

Next, a third opening 13 is formed in the back electrode 8 by mechanical cutting means. The third opening 13 is
At a position about 100 μm away from the second opening 12, 50
It is formed with a width of about μm.

At this time, various shapes can be considered as the cross-sectional shape of the cut groove formed by the mechanical cutting means.

FIG. 4 is a sectional view showing an example of the shape of these cut grooves. Referring to FIG. 4, the cross-sectional shape of the cutting groove formed by the mechanical cutting means is, for example, as shown in FIG.
A V-shaped groove 13A shown in FIG. 4A, a U-shaped groove 13B shown in FIG. 4B, a rectangular groove 13C shown in FIG.
There is an inverted trapezoidal groove 13D shown in FIG.

(Embodiment 2) A resist is used for patterning the back surface, a resist is applied on the back electrode after the formation of the back electrode, the resist is cut by a mechanical cutting means, patterned, and then the back electrode is etched. By doing so, the back electrode is patterned.

The other steps are exactly the same as those of the first embodiment, and the description is omitted.

[0044]

EXAMPLES (Example 1) An integrated thin-film solar cell was actually manufactured according to the method of the first embodiment.

As the mechanical cutting means, a small carbide tool having a V-shaped cutting groove was used. A constant pressure of about 30 g is applied between the mechanical cutting means and the back electrode by a smile spring, and the moving speed of the mechanical cutting means is 60 times, which is three times the scribe speed of the conventional laser scribe method.
0 mm / sec.

Thus, 650 mm × 910 mm
100 integrated thin-film solar cells in which 90 unit cells were integrated in series on a relatively large-area substrate were manufactured.

The output characteristics of the 100 thin-film solar cells obtained in this manner were the same as those of the 100 thin-film solar cells manufactured in the same manner as in this example except that the back electrode was processed by the laser scribe method. When the average characteristics of 100 pieces were compared, the open-circuit voltage was 1.1, the short-circuit current was 1.0, and the fill factor was 1.1.
The output voltage was as good as 1.21. In addition, the time required for patterning the back electrode was reduced to one third of that of the laser scribe method in the case of the present embodiment.

From the above results, it was confirmed that according to the present invention, the patterning of the back electrode can be performed stably, accurately, and in a short time even with a large-area substrate.

Example 2 According to the method of the second embodiment,
Actually, 100 integrated thin-film solar cells were produced.

The output characteristics of the 100 thin-film solar cells obtained in this manner were the same as those of the present embodiment except that the resist on the back electrode was processed by the laser scribe method. By comparing the output characteristics with 1,
The highest characteristics were almost the same, but in the average characteristics of 100 pieces, the open circuit voltage was 1.2, the short-circuit current was 1.0, the fill factor was 1.2, and the output voltage was 1.44. Also,
In the present embodiment, the time required for patterning the back electrode was reduced to 1/3 of that of the laser scribe method.

From the above results, it was confirmed that, according to the present invention, patterning of the back electrode can be performed stably, accurately, and in a short time even with a large-area substrate.

Example 3 An integrated thin-film solar cell was manufactured in the same manner as in Example 2 except that 72 mechanical cutting means were arranged at regular intervals, and 72 cuts were made at once. This was produced.

The output characteristics of the 100 thin-film solar cells obtained in this manner were the same as those of the present embodiment except that the resist on the back electrode was processed by the laser scribe method. By comparing the output characteristics with 1,
The highest characteristics were almost the same, but in the average characteristics of 100 pieces, the open-circuit voltage was 1.1, the short-circuit current was 1.0, the fill factor was 1.2, and the output voltage was 1.32. Also,
In the case of this embodiment, the time required for patterning the back electrode was significantly reduced to 1/216 that of the laser scribe method.

From the above results, it was confirmed that, according to the present invention, patterning of the back electrode can be performed stably and accurately even in a large-area substrate in an extremely short time.

(Embodiment 4) After the resist on the back electrode is once cut by laser scribing and patterned,
100 integrated thin-film solar cells were produced in the same manner as in Example 2 except that only the defective cutting portions were cut by mechanical cutting means.

The defect at the portion cut and patterned by the laser scribe method is specified by measuring the electric resistance between the adjacent back electrodes for each integrated stage, and the separation resistance is determined to be 10 or less.
A portion having a resistance of 0Ω or less was determined to be defective in patterning, and further cut and patterned by a mechanical cutting means.

The output characteristics of the 100 thin-film solar cells obtained in this manner were set to 1, with the output characteristics of 100 thin-film solar cells manufactured by processing the resist on the back electrode only by the laser scribe method. By comparison, the average characteristics of 100 pieces were as good as 1.2 in open-circuit voltage, 1.0 in short-circuit current, 1.2 in fill factor, and 1.44 in output voltage.

From the above results, it was confirmed that according to the present invention, it is possible to stably and accurately pattern the back surface electrode even on a large-area substrate that could not be completely cut by only the laser scribe method. .

[0059]

As a result of repeated experiments, the present inventor has found that the amorphous silicon film of an amorphous silicon solar cell is extremely hard, and it is difficult to mechanically pattern the amorphous silicon film with a cutting tool. The inventors have found that the back electrode and the resist film formed thereon can be mechanically patterned without cutting the underlying amorphous silicon film, and have accomplished the present invention.

That is, according to the method of manufacturing an integrated thin-film solar cell according to the present invention, in manufacturing an integrated thin-film solar cell in which a plurality of solar cells are connected in series on a substrate, the backside electrode is patterned by a conventional laser scriber. From the law,
By changing to mechanical cutting by mechanical cutting means and patterning, even if the substrate has a large area, high pattern processing accuracy can be maintained, and a higher processing speed can be obtained as compared with the laser scribe method. .

In particular, according to the first aspect of the present invention, the back electrode can be processed in a simple process without using an auxiliary material such as a resist.

According to the second aspect of the present invention, since the resist is used for processing the back electrode, the mechanical cutting means cuts a relatively soft resist material, so that only the resist is selectively cut. And the semiconductor thin film beneath the cut portion is less likely to be damaged.

According to the third aspect of the present invention, when processing is performed using the mechanical cutting means, patterning is performed while applying a constant pressure to the surface to be processed, so that bending and warping of the substrate can be prevented. Even if it does, the cutting depth can be kept constant, and processing can be performed without damaging the semiconductor thin film under the cut portion.

According to the fourth aspect of the present invention, by arranging a plurality of mechanical cutting means, the number of places that can be processed simultaneously can be increased, and the processing speed can be easily increased.

According to the fifth aspect of the present invention, it is possible to easily correct a patterning defective portion after performing the conventional laser scribe method.

Further, according to the invention of claim 6, by optimizing the cutting width by the mechanical cutting means, the accuracy and reliability of patterning can be improved.

[Brief description of the drawings]

FIG. 1 is a schematic view of an example of a manufacturing apparatus capable of implementing a method of manufacturing an integrated thin-film solar cell according to the present invention.

FIG. 2 is a cross-sectional view of an integrated structure for dividing cells on a substrate and connecting them in series in the method of manufacturing an integrated thin-film solar cell according to the present invention.

FIG. 3 is a plan view of the solar cell shown in FIG. 2 as viewed from the back electrode side.

FIG. 4 is a cross-sectional view showing an example of the shape of a cutting groove.

FIG. 5 is a cross-sectional view schematically illustrating a structure of an example of a conventional integrated thin-film solar cell.

[Explanation of symbols]

1 mechanical cutting means, 2 pressure applying means, 3 moving means, 5 glass substrate, 6 transparent conductive film, 7 photoelectric conversion layer,
8 back electrode (or laminate of back electrode and resist), 11 first opening, 12 second opening, 13A,
13B, 13C, 13D Third opening, 14 scribe line, 15 peripheral part of substrate. In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (6)

[Claims] 1. A method of manufacturing an integrated thin-film solar cell in which a plurality of solar cells made of an amorphous silicon-based semiconductor are connected in series on a light-transmitting insulating substrate, wherein an electrode made of a metal thin film is formed on the amorphous silicon-based semiconductor. And a step of mechanically dividing and patterning the deposited electrode by a mechanical cutting means. 2. A method of manufacturing an integrated thin-film solar cell in which a plurality of solar cells made of an amorphous silicon-based semiconductor are connected in series on a light-transmitting insulating substrate, wherein an electrode made of a metal thin film is formed on the amorphous silicon-based semiconductor. Depositing and forming; depositing a resist on the deposited electrode; mechanically dividing the applied resist by mechanical cutting means to perform patterning; and Etching the electrode from a resist to divide and pattern the electrode, and manufacturing the integrated thin-film solar cell. 3. The step of patterning the electrode or the resist, wherein the electrode or the resist is completely divided, and
3. The method according to claim 1, wherein the mechanical cutting unit is moved, cut, and patterned while applying a pressure in a range in which the amorphous silicon-based semiconductor is not completely divided. 4. A method for manufacturing an integrated thin-film solar cell. 4. A plurality of said mechanical cutting means are arranged at regular intervals, and said mechanical cutting means and said electrode or said resist are relatively moved, so that said electrode or said resist is simultaneously placed at a constant interval. The method of manufacturing an integrated thin-film solar cell according to claim 1, wherein the patterning is performed by mechanical cutting. 5. The method according to claim 1, wherein the mechanical cutting and patterning by the mechanical cutting means are performed on a patterning defective portion after patterning the electrode with a laser beam. 3. The method for manufacturing an integrated thin-film solar cell according to any one of 3. 6. The width of the mechanical cutting by the mechanical cutting means is 0.03 to 0.3 mm,
A method for manufacturing an integrated thin-film solar cell according to any one of claims 1 to 5.