JP3091151B2 - Manufacturing method of integrated photovoltaic device - Google Patents

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.

A general a-Si photovoltaic device comprises a transparent conductive film, a p-type, i-type, and n-type a-Si film on a glass substrate.
The back metal electrode film is formed by laminating in this order. In the integrated a-Si photovoltaic device, a large number of photoelectric conversion elements are connected in cascade so that a high voltage is taken out from one substrate as a whole.

In order to form an integrated structure, it is necessary to separate a transparent conductive 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 of manufacturing an integrated photovoltaic device using a conventional laser patterning method will be described with reference to FIG.
FIG. 2 is an enlarged cross-sectional view of a main part showing a conventional method of manufacturing an integrated photovoltaic device for each process, and mainly shows an adjacent space where two photoelectric conversion elements are electrically connected in series.

A transparent conductive film 2 made of ITO, SnO ₂ or the like is formed on one main surface of an insulative light-transmitting substrate 1 made of glass or the like. It is divided into strips (see FIG. 2A). Then, an amorphous semiconductor layer 3 made of an a-Si film having a pin junction inside is deposited on the divided transparent conductive film 2 (see FIG. 2B).

After that, a laser beam is irradiated from the other main surface side of the substrate 1 along the dividing line of the transparent conductive film 2 so as not to overlap with the dividing line, thereby forming the amorphous semiconductor layer 3.
The hydrogen in the inside is rapidly released, the amorphous semiconductor layer is removed by the release of the hydrogen, and the amorphous semiconductor layer 3 is divided (see FIG. 2C).

Subsequently, a back metal electrode film 4 of aluminum or the like is formed on the amorphous semiconductor layer 3, and the transparent conductive film 2 and the back metal electrode film 4 are connected (see FIG. 2D). Thereafter, a laser beam is irradiated from the other main surface side of the substrate 1 along the dividing line of the transparent conductive film 2 and the amorphous semiconductor layer 3 so as not to overlap with both dividing 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. 2E).

[0009]

By the way, as the film thickness of the amorphous semiconductor layer is optimized and the development of a stacked photovoltaic device using a narrow band gap material is advanced with the countermeasures against light deterioration and the improvement of the conversion efficiency, Amorphous semiconductor layers are becoming thinner.

[0010] With the thinning of the amorphous semiconductor layer, the absolute amount of hydrogen in the amorphous semiconductor layer becomes insufficient when patterning the back metal electrode, and the back metal electrode film is not completely removed. there were. In particular, when the thickness of the amorphous semiconductor layer is 3
If the temperature is less than 000 °, processing defects due to shortage of the absolute amount of hydrogen in the amorphous semiconductor layer become remarkable, and there is a problem that sufficient characteristics cannot be obtained.

The present invention has been made in consideration of the above-mentioned conventional problems, and has been made in consideration of the above circumstances.
An object of the present invention is to provide a method of manufacturing an integrated photovoltaic device that prevents the occurrence of processing defects of a back metal electrode film.

[0012]

According to a method of manufacturing an integrated photovoltaic device of the present invention, a transparent conductive film, an amorphous semiconductor layer and a back metal electrode film are formed on one main surface of a light transmitting substrate. A method of manufacturing an integrated type photovoltaic device formed in order, wherein at least a part of a transparent conductive film in a processing region is made amorphous, and a laser beam is applied to the processing region from the other main surface side of the light-transmitting substrate. Irradiation is performed to remove the amorphous semiconductor layer and the back metal electrode film on the processing region.

By injecting ions into the surface of the transparent conductive film, the surface of the transparent conductive film can be made amorphous.

According to the above method, the element of the transparent conductive film is also released together with the release of hydrogen from the amorphous semiconductor layer. Element, and the back metal electrode film can be reliably removed.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method of manufacturing an integrated photovoltaic device using a laser patterning method according to an embodiment of the present invention will be described below with reference to FIG. In the embodiment of the present invention, a-Si and a-SiG are used as amorphous semiconductor layers.
This is applied to a so-called tandem-structure integrated photovoltaic device in which e is multilayered. FIG. 1 is an enlarged cross-sectional view of a main part showing a method of manufacturing an integrated photovoltaic device according to the present invention for each step, and mainly shows an adjacent space where two photoelectric conversion elements are electrically connected in series. .

On one main surface of the insulating translucent substrate 1 made of glass, a film thickness of 0.2 to 1 μm, in this embodiment about 1 μm.
The transparent conductive film 2 made of SnO _{2 having} a thickness of μm is formed by thermal CVD.
It is formed by a method or the like. Thereafter, for example, the transparent conductive film 2 is divided into strips in an arbitrary number of steps by laser beam irradiation. Then, the transparent conductive film at the position located on the rear surface metal electrode processing portion 5 is made amorphous to form an amorphous region 2a (see FIG. 1A).

In this embodiment, the amorphous region 2a is formed by implanting Sn ⁺ ions. Sn ⁺ ions are accelerated at a voltage of 50 keV and a temperature of 300.
The amorphous region 2 having a depth of about 0.2 μm is formed by ion implantation at a temperature of 2 ° C. and a dose amount of 2 × 10 ¹⁵ cm ^−2.
a was formed.

The formation of the amorphized region 2a may be performed after the transparent conductive film 2 is divided or before the division.

The total thickness of the a-Si film having a pin junction and a-SiGe laminated on the transparent conductive film 2 having the amorphized region 2a formed thereon is 0.3 to 0.5 μm. A degree of amorphous semiconductor layer 3 is deposited (FIG. 1).
(B)). In this embodiment, an amorphous semiconductor layer 3 having a total thickness of about 0.3 μm is formed by plasma CVD.
It was formed by a method.

Thereafter, a laser beam is irradiated from the other main surface side of the substrate 1 along the division line of the transparent conductive film 2 so as not to overlap with the division line, and the amorphous semiconductor layer 3 is irradiated.
The hydrogen in the inside is rapidly released, and the release of the hydrogen removes the amorphous semiconductor layer to divide the amorphous semiconductor layer 3 (see FIG. 1C).

In this laser patterning, even if the absolute amount of hydrogen in the amorphous semiconductor layer 3 is insufficient and the separation of the amorphous semiconductor layer 3 is not sufficient, a part of the transparent conductive film 2 can be formed. Is exposed, there is no problem because electrical connection with the back metal electrode film 4 formed in the next step can be made.

Subsequently, a back metal electrode film 4 made of aluminum or the like and having a thickness of about 0.5 μm is formed on the amorphous semiconductor layer 3 by sputtering, so that the transparent conductive film 2 and the back metal electrode film 4 are formed.
(See FIG. 1D).

Thereafter, along the dividing line of the transparent conductive film 2 and the a-Si film 3, the laser beam is applied from the other main surface side of the substrate 1 to the back metal electrode processing portion 5, that is, to the amorphous region 2 a. To rapidly release hydrogen in the amorphous semiconductor layer 3 and oxygen (O) in the amorphized region 2a to remove the amorphous semiconductor layer and the back metal electrode film thereon. The adjacent cells are separated (see FIG. 1E).

As described above, SnO _2, which is usually polycrystalline,
By amorphizing a part of the film and providing the amorphized region 2a, a portion having a weak bonding force is formed, and the release of oxygen contained in SnO ₂ becomes easy. As a result, by irradiating the amorphous region 2a with a laser beam, oxygen is released, and the shortage of hydrogen in the amorphous semiconductor layer 3 is compensated for, whereby the back metal electrode film 4 can be reliably separated.

Next, in order to evaluate the patterning of the back metal electrode film in the conventional integrated photovoltaic device and the integrated photovoltaic device of the present invention, a 10 cm square, 12-stage integrated a-Si / a- A photovoltaic device having a SiGe tandem structure was prepared, and low-intensity Voc measurement (measured under a 10,000-lux fluorescent lamp) of each stage was performed. Table 1 shows the Voc measurement results at that time, and Table 2 shows the output characteristics.

The photovoltaic device according to the present invention is manufactured by the above-described manufacturing method, and the conventional photovoltaic device is manufactured under the same conditions as those of the present invention except that an amorphous region is not formed in the transparent conductive film. did.

[0027]

[Table 1] (Unit: mV)

[0028]

[Table 2]

Here, Voc is an open circuit voltage, Isc is a short circuit current, and F.C. F. Is the fill factor and _Pmax is the output. The cell area was 10 cm square, and the irradiation light was AM 1.5, 10
0 mW / cm ² .

As is apparent from Tables 1 and 2, the integrated photovoltaic device manufactured by the method of the present invention has a thinner amorphous semiconductor layer than the photovoltaic device manufactured by the conventional method. As a result, low illuminance Voc was improved, and good output characteristics were obtained.

In the above-described embodiment, as the method for amorphizing the transparent conductive film, ion implantation using Sn ⁺ ions is used. However, other ion species (for example, Si ⁺ ions) may be used, or a laser may be used. It is also possible to use a surface quenching method of instantaneously heating and cooling by irradiating a beam.

Further, by implanting ions of rare gas elements such as He, Ne, and Ar into SnO ₂ , an amorphous region is formed, and these rare gas elements are emitted by laser beam irradiation. It is also possible to compensate for the shortage of hydrogen in the amorphous semiconductor layer and to reliably separate the back metal electrode film. .

[0033]

As described above, according to the present invention, a shortage of hydrogen in a thinned amorphous semiconductor layer is caused by an element released from an amorphous region of a transparent conductive film. Is compensated, the back metal electrode film can be processed reliably, and the output characteristics of the integrated photovoltaic device can be improved.

[Brief description of the drawings]

FIG. 1 is an enlarged sectional view of a main part showing a method of manufacturing an integrated photovoltaic device according to the present invention in each step.

FIG. 2 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 Substrate 2 Transparent conductive film 2a Amorphous region 3 Amorphous semiconductor layer 4 Back metal electrode

Continuation of front page (56) References JP-A-6-151914 (JP, A) JP-A-3-79085 (JP, A) JP-A-63-121685 (JP, A) (58) Fields investigated (Int .Cl. ⁷ , DB name) H01L 31/04-31/078

Claims (2)

(57) [Claims] 1. A transparent conductive film on one main surface of a translucent substrate,
A method of manufacturing an integrated photovoltaic device in which an amorphous semiconductor layer and a backside metal electrode film are formed in this order, wherein at least a part of a transparent conductive film in a processing region is made amorphous and the transparent conductive film is formed in the processing region. Irradiate the laser beam from the other main surface side of the optical substrate,
A method of manufacturing an integrated photovoltaic device, comprising removing an amorphous semiconductor layer and a back metal electrode film on a processing region. 2. The method of manufacturing an integrated photovoltaic device according to claim 1, wherein the surface of the transparent conductive film is made amorphous by implanting ions into the surface of the transparent conductive film.