JP2001094131A - Method for fabricating integrated photovoltaic power device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate defective machining in laser patterning. SOLUTION: A thin transparent electrode film, a thin amorphous semiconductor film and a thin rear surface material electrode are formed sequentially on one major surface of a translucent substrate 11 in the fabrication method of an integrated photovoltaic device. A thin film 11a formed on the substrate is placed in a machining container 6 and irradiated with a laser beam for patterning with the surface of the thin film 11a in a state of making contact with an incombustible liquid 7.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing an integrated photovoltaic device using an amorphous semiconductor.

[0002]

2. Description of the Related Art In recent years, photovoltaic devices using an amorphous silicon (a-Si) semiconductor as a photoactive layer have been used for various purposes. This largely depends on the development of an integrated a-Si photovoltaic device that can take out a high voltage by cascading a large number of photoelectric conversion elements on one substrate.

[0003] A general a-Si photovoltaic device comprises a transparent conductive thin film, p-type, i-type, and n-type a-Si on a glass substrate.
It is formed by laminating a film and a back metal electrode film in this order.
Then, the integrated a-Si photovoltaic device has 1
A large number of photoelectric conversion elements are connected in cascade so as to extract a high voltage from a single substrate.

In order to form an integrated structure, it is necessary to separate a transparent conductive thin film, an a-Si film, and a metal electrode film on a glass substrate. As a method of separating each film, a laser patterning method using a laser is mainly used (for example, see Japanese Patent Publication No. 4-64473).

A method for manufacturing an integrated photovoltaic device using a conventional laser patterning method will be described with reference to FIG.
FIG. 8 is an enlarged cross-sectional view of a main part showing a conventional method of manufacturing an integrated photovoltaic device for each step, and mainly shows an adjacent space where two photoelectric conversion elements are electrically connected in series.

A transparent conductive thin film 12 made of ITO (In ₂ Sn ₂ O ₃ ) or SnO ₂ is formed on one main surface of an insulating translucent substrate 11 made of glass or the like. The conductive thin film 12 is divided into strips having an arbitrary number of steps (see FIG. 8A). Then, an amorphous semiconductor layer 13 made of an a-Si film having a pin junction is deposited on the divided transparent conductive thin film 12 (see FIG. 8B).

After that, a laser beam is irradiated from the other main surface side of the substrate 11 along the dividing line of the transparent conductive thin film 12 so as not to overlap the dividing line, and the amorphous semiconductor layer is released by the release of hydrogen. Is removed to divide the amorphous semiconductor layer 13 (see FIG. 8C).

Subsequently, a back metal electrode film 14 of aluminum or the like is formed on the amorphous semiconductor layer 13 and the transparent conductive thin film 12 and the back metal electrode film 14 are connected (FIG. 8D).
reference). Thereafter, a laser beam is irradiated from the other main surface side of the substrate 11 along the division line of the transparent conductive thin film 12 and the amorphous semiconductor layer 13 so as not to overlap with both division lines. The hydrogen in the cell is rapidly released to remove the amorphous semiconductor layer and the back metal electrode film thereon, thereby separating adjacent cells (see FIG. 8E).

[0009]

In the above-mentioned patterning method using a laser beam, the available laser output and the conditions of each layer, that is,
There are disadvantages such as the amount of hydrogen and the thickness of the amorphous silicon layer, the material and thickness of the back metal electrode film, the material of the transparent conductive thin film, and the like are limited.

In the case of an amorphous silicon layer, if the output of the laser is too low, the scattered melted substances are reattached to the substrate, causing a defect. Further, if the output is too high, there is a problem that the processed end face of the amorphous silicon layer is melted and recrystallized and short-circuited.

In the transparent conductive thin film layer, scattered matter may cause a remarkable defect depending on the material.

For example, the processed portion of the transparent conductive thin film layer made of SnO ₂ is vaporized by laser irradiation, but the transparent conductive thin film layer made of ZnO is scattered in a molten state, so that it is easily re-attached particularly around the processed portion. . Therefore, when processing a transparent conductive thin film layer made of ZnO with a laser, the wavelength and output of the laser are particularly limited to a narrow range.

The present invention has been made in consideration of the above-mentioned conventional problems, and has as its object to eliminate processing defects in a laser patterning method.

[0014]

SUMMARY OF THE INVENTION The present invention provides an integrated photovoltaic device in which a transparent conductive thin film, an amorphous semiconductor thin film, and a back metal electrode thin film are formed in this order on one main surface of a translucent substrate. The method according to any one of claims 1 to 3, characterized in that any one of the thin films or the plurality of thin films is patterned by irradiating an energy beam with the surface in contact with a nonflammable liquid.

Further, when patterning a thin film including the amorphous semiconductor thin film, a sodium hydroxide solution is used as the nonflammable liquid.

The solid / liquid interface has a higher thermal conductivity than the solid / gas interface. Therefore, it is possible to prevent the scattered matter from being welded to the patterned end face having a higher cooling effect than the gas and to prevent the edge portion from being melted and deformed.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. The same parts as those of the conventional example are denoted by the same reference numerals.

FIG. 1 is a schematic side view showing the structure of a patterning apparatus using a laser to which the present invention is applied.

This laser patterning apparatus is a YAG
(Yttrium aluminum garnet) The laser beam 2 emitted from the laser oscillation device 1 is reflected by the reflection mirror 3
To change the direction, condensed by the condenser lens 4 and placed on the moving table 5 comprising an XYZ stage.
Irradiates the region to be processed. The workpiece 10 is immersed in a processing container 6 in which a non-flammable liquid 7 such as water or silicone oil is stored inside a moving table 5. The pattern is controlled by moving the moving table 5 on which the workpiece 10 is placed. While moving the moving table 5, the processing area of the thin film 11a formed on the substrate 11 is irradiated with a laser beam to remove the thin film in the processing area. At this time, the surface of the thin film 11a to be patterned is in contact with the liquid. The interface between solid and liquid has a higher heat transfer coefficient than the interface between solid and gas. Therefore, it is possible to prevent the flying matter from being welded to the patterned end face having a higher cooling effect than the gas and to prevent the edge portion from being melted and deformed. That is, crystallization of amorphous silicon and dripping of metal on the processed end face can be reduced. In addition, since liquid has higher resistance than gas, there is also an effect that diffusion of flying matter can be prevented.

In the above-mentioned apparatus, the liquid 7 may be circulated or stirred to enhance the cooling effect.

Next, a specific example of a method of manufacturing an integrated photovoltaic device to which the present invention is applied will be described with reference to FIG.
FIG. 2 is an enlarged sectional view of a main part showing a method of manufacturing an integrated type photovoltaic device according to the present invention in each step, and mainly shows an adjacent space where two photoelectric conversion elements are electrically connected in series. .

A transparent conductive thin film 12 made of SnO ₂ having a thickness of 0.2 to 1 μm, in this embodiment, about 0.8 μm, is formed on one main surface of an insulating translucent substrate 11 made of glass.
Is formed by a thermal CVD method or the like. After that, the substrate 11 is immersed in the processing container 6 storing water as the liquid 7. Wavelength 1.
06 μm, pulse frequency 3 kHz, energy density 13
A transparent conductive thin film 1 is irradiated with a YAG laser ² of J / cm ^2.
2 is divided into strips of an arbitrary number of steps (see FIG. 2A).

After the substrate is washed, the front a-Si having a pin junction inside on the transparent conductive thin film 12 is formed.
An amorphous semiconductor layer 13 having a total thickness of about 0.3 to 0.5 μm in which the film and the bottom a-SiGe are stacked is deposited by a plasma CVD method (see FIG. 2B). In this embodiment, the amorphous semiconductor layer 13 having a total thickness of about 0.4 μm is formed by a plasma CVD method. In this embodiment, the amorphous semiconductor layer 13 is
a 100-angstrom thick front p-type amorphous semiconductor layer made of a-SiC and a film thickness 10 made of a-SiC
A front buffer layer having a thickness of 0 Å, a front i-type amorphous semiconductor layer having a thickness of 2,000 Å made of a-Si, a front n-type amorphous semiconductor layer having a thickness of 200 Å made of a-Si, and a-SiC. A bottom p-type amorphous semiconductor layer having a thickness of 300 angstroms, a bottom i-type amorphous semiconductor layer having a thickness of 2000 angstroms made of a-SiGe, and a bottom n-type amorphous semiconductor having a thickness of 200 angstroms made of a-Si: H. And a high-quality semiconductor layer.

Thereafter, the substrate 11 is immersed in the processing container 6 in which water is stored as the liquid 7. YAG having a wavelength of 0.53 μm, a pulse frequency of 4 kHz, and an energy density of 0.7 J / cm ²
The amorphous semiconductor layer 13 is divided by irradiating the laser 2 along the division line of the transparent conductive thin film 12 so as not to overlap with the division line (see FIG. 2C).

Subsequently, after cleaning the substrate, the amorphous semiconductor layer 1
2,000 Å of Al and a thickness of 20 on 3
A back metal electrode film 14 made of a laminated film of 00 Å Ti is formed by a sputtering method, and the transparent conductive thin film 12 and the back metal electrode film 14 are connected. (FIG. 2 (d)
reference).

Thereafter, the substrate 11 is immersed in the processing container 6 in which water is stored as the liquid 7. YAG having a wavelength of 0.53 μm, a pulse frequency of 4 kHz, and an energy density of 0.7 J / cm ²
A laser 2 is irradiated on the back metal electrode processing portion along the dividing line of the transparent conductive thin film 12 and the amorphous semiconductor layer 13,
The back metal electrode film 14 is melted to remove the amorphous semiconductor layer and the back metal electrode film thereon, thereby separating adjacent cells (see FIG. 2E).

Thus, the integrated photovoltaic device according to the present invention is manufactured.

The interface between the solid and the liquid has a higher heat transfer coefficient than the interface between the solid and the gas. Therefore, the cooling effect is higher than that of the gas, and it is possible to prevent the welding of the scattered matter and the melting deformation of the edge portion. That is, crystallization of amorphous silicon and dripping of metal on the processed end face can be reduced. Further, the melted splatter can be cooled to prevent re-adhesion (welding). In addition, since liquid has higher resistance than gas, there is also an effect that diffusion of flying matter can be prevented.

As a result, conventionally, an energy density of 10
If it increases by up to 50%, problems such as melting of the electrode layer and crystallization of the amorphous layer occur. However, according to the present invention, it becomes possible to use twice as much energy density as the conventional one, and the range of selection of the conditions of the layer to be processed becomes wider. Spread.

In the above-described embodiment, water is used as the liquid stored in the processing container 6, but the liquid is
Any non-flammable substance may be used, and in addition to water, a silicone oil or a chemical solution that does not adversely affect the workpiece is used.

When an aqueous solution of sodium hydroxide is used as the liquid for patterning the semiconductor layer 13 and the back metal electrode film 14, the semiconductor layer is etched by laser patterning and the etching action of the aqueous sodium hydroxide solution. Is accelerated and the time required for patterning can be reduced. As the aqueous sodium hydroxide solution, a 0.1 wt% solution may be used.

In the above embodiment, the case where SnO ₂ is used as the transparent conductive thin film 12 has been described. However, the same effect can be obtained by using ZnO as the transparent conductive thin film. In particular, the transparent conductive thin film made of ZnO is scattered in a molten state during laser processing, and thus easily adheres to the periphery of the processed portion. However, according to the present invention, reattachment of the scattered matter can be prevented. According to the present invention, when laser processing a transparent conductive thin film layer made of ZnO, the wavelength and output of the laser can be set in a wider range than before.

FIG. 3 is a schematic view showing a state in which the workpiece 10 is set in the processing vessel 6 in the above-described laser patterning apparatus, laser patterning is performed, and the workpiece 10 is taken out.

First, the workpiece 10 is set in the processing container 6 (see FIG. 3A). Subsequently, the liquid 7 such as water is supplied from the water supply / drain port 21 into the processing container 6 using the pump 20 (see FIG. 3B). When the supply of a predetermined amount of liquid is completed, a laser beam is applied to a region to be processed of the workpiece 10 to perform patterning. When the processing is completed, the pump 20 drains the liquid 7 from the processing container 6 (FIG. 3).
(C)). Then, the workpiece 10 is removed from the processing vessel 6.
Take out.

In the above-described embodiment, the method of irradiating the laser beam from the film surface 11a side of the glass substrate 11 has been described. However, the case of processing by irradiating the laser beam from the glass surface side will be described.

When processing is performed by irradiating a laser beam from the glass substrate 11 side of the workpiece 10, the film surface of the thin film 11 a in the processing area is brought into contact with the liquid 7. As shown in FIG. 4, a processing vessel 6 is filled with a liquid 7 such as water,
The substrate 11 is placed with the film surface 1a facing the processing vessel 6 side. At this time, the processing container 6 is filled with the liquid 7 so that the film surface of the region to be processed of the thin film 11 a formed on the substrate 11 is in contact with the liquid 7. This processing container 6 is also set on a moving table, as in the above-described embodiment.

Then, the laser beam 2 is applied to the glass substrate 11.
Irradiation is performed from the side, and the processing area of the thin film 11a such as a transparent conductive thin film is removed by the laser beam 2 while controlling the moving table in the XYZ directions.

As described above, the interface between the solid and the liquid has a higher heat transfer coefficient than the interface between the solid and the gas. Therefore, the cooling effect is higher than that of the gas, and it is possible to prevent the welding of the flying matter and the melting deformation of the edge portion. That is, crystallization of amorphous silicon and dripping of metal on the processed end face can be reduced.

In the example shown in FIG. 4, since only the end of the substrate 11 is supported, if the substrate 11 becomes large, there is a possibility that bending occurs. Therefore, in the embodiment shown in FIGS. 5 and 6, in order to prevent the substrate 11 from bending, the support member 6 is placed in the processing container 6 while avoiding the region to be processed.
a, and the substrate 11 is supported by the support member 6a.

The film surface on the processing region side of the substrate 11 is supported by the support member 6a. The film surface of the region to be processed is in a state where the liquid 7 filled in the processing container 6 is in contact therewith. This processing container 6 is also set on a moving table, as in the above-described embodiment.

Then, a laser beam is irradiated from the glass substrate 11 side, and the processing area of the thin film 11a such as a transparent conductive thin film is removed by the laser beam while controlling the moving table in the XYZ directions. Although the support member 6a shown in FIGS. 5 and 6 is formed in a rectangular shape, any shape can be used as long as it can support, such as a bar.

The embodiment shown in FIG. 7 uses a processing container 6 having a structure in which a moisture absorbing material 6b immersed in a liquid is brought into contact with a film surface of a region to be processed. A liquid exists at the interface between the film surface and the hygroscopic agent 6b due to surface tension. This processing container 6 is also set on a moving table, as in the above-described embodiment.

Then, a laser beam is irradiated from the glass substrate 11 side, and the processing area of the thin film 11a such as a transparent conductive thin film is removed by the laser beam while controlling the moving table in the XYZ directions.

[0044]

As described above, according to the present invention, since the interface between the solid and the liquid has a higher heat transfer coefficient than the interface between the solid and the gas, the cooling effect during laser processing is improved, and the scattered matter is deposited. And the edge portion can be prevented from being melted and deformed, and the integrated photovoltaic device can be manufactured efficiently.

In particular, according to the present invention, when a transparent conductive thin film layer made of ZnO is processed with a laser, the wavelength and output of the laser can be set in a wider range than in the past.

[Brief description of the drawings]

FIG. 1 is a schematic side view showing a configuration of a patterning apparatus using a laser to which the present invention is applied.

FIG. 2 is an enlarged sectional view of a main part showing a method of manufacturing an integrated photovoltaic device according to the present invention for each step.

FIG. 3 is a schematic diagram showing a state in which a substrate is set in a processing container, laser patterning is performed, and the substrate is taken out in the laser patterning apparatus used in the present invention.

FIG. 4 is a schematic side view showing another embodiment of the present invention.

FIG. 5 is a schematic perspective view showing a different embodiment of the present invention.

FIG. 6 is a schematic side view showing a different embodiment of the present invention.

FIG. 7 is a schematic side view showing still another embodiment of the present invention.

FIG. 8 is an enlarged sectional view of a main part showing a method of manufacturing a conventional integrated photovoltaic device for each process.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Laser oscillation device 2 Laser beam 5 Moving table 6 Processing container 7 Liquid 10 Workpiece 11 Substrate 11a Thin film

 ──────────────────────────────────────────────────続 き Continued on front page F term (reference) 4E068 AB00 CJ07 DA09 5F004 AA09 BB03 BB31 CA05 DB00 DB08 DB30 DB31 EA38 EB02 FA05 5F033 HH03 HH05 HH40 QQ08 QQ19 QQ53 XX00 5F051 AA05 CB29 DA04 EA05 EA09 EA09 EA09

Claims (3)

[Claims] 1. A method of manufacturing an integrated photovoltaic device, comprising: forming a transparent conductive thin film, an amorphous semiconductor thin film, and a back metal electrode thin film on one main surface of a light-transmitting substrate in this order; A method of manufacturing an integrated photovoltaic device, characterized in that any one or a plurality of thin films is patterned by irradiating an energy beam with a surface in contact with a nonflammable liquid. 2. The integrated photovoltaic device according to claim 1, wherein when patterning the thin film including the amorphous semiconductor thin film, a sodium hydroxide solution is used as the nonflammable liquid. Method. 3. The transparent conductive thin film is made of ZnO, and is patterned by irradiating an energy beam with the surface of the transparent conductive thin film made of ZnO in contact with a nonflammable liquid. 3. The method for manufacturing an integrated photovoltaic device according to item 2.