JP2648064B2 - Method for manufacturing optical semiconductor device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an optical semiconductor device such as a photovoltaic device or a photoconductive device.

[0002]

2. Description of the Related Art In this type of device, a device using a semiconductor film such as amorphous silicon for a light-sensitive layer is already known.

FIG. 1 shows a conventional optical semiconductor device using an amorphous semiconductor film, wherein 1 is a transparent substrate, 2a, 2b, 2c.
.. Are transparent conductive films deposited at regular intervals on the substrate 1;
a, 3b, 3c... are superposed and deposited on each transparent conductive film, 4a, 4b, 4c. Transparent conductive film 2 on the right
b, 2c... are back electrode films that partially overlap with each other.

Each of the amorphous semiconductor films 3a, 3b, 3c...
Contains, for example, a PIN junction parallel to the film surface inside,
Therefore, the transparent substrate 1 and the transparent conductive films 2a, 2b, 2c
.. If light is incident sequentially through, a photoelectromotive force is generated. The photovoltaic power generated in each of the amorphous semiconductor films 3a, 3b, 3c... Is added in series by the connection at the back electrode films 4a, 4b, 4c.

[0005] In such a device, one factor that affects the light utilization efficiency is that the amorphous semiconductor film 3 that actually contributes to power generation is compared with the light receiving area (ie, substrate area) of the entire device.
a, 3b, 3c,... are ratios of the total area. However, the area ratio (area indicated by NON in the figure) where there is no amorphous semiconductor film necessarily present between the adjacent amorphous semiconductor films 3a, 3b, 3c... Decreases the area ratio.

Therefore, in order to improve the light use efficiency, the distance between the adjacent transparent conductive films 2a, 2b, 2c... Is first reduced, and the distance between the adjacent amorphous semiconductor films 3a, 3b, 3c. Must be small.

[0007] Such a reduction in the interval is determined by the processing accuracy of each film. Therefore, conventionally, a photolithography technique which is excellent in precision workability has been used. In the case of this technique, a step of depositing a transparent conductive film over the entire surface of the substrate 1 and individual transparent conductive films 2a, 2b, 2c.
Separation of the transparent conductive films 2a, 2b, 2c
A step of removing an adjacent space portion, and a step of depositing an amorphous semiconductor film on the entire surface of the substrate 1 including on each of these transparent conductive films.
The separation of the individual amorphous semiconductor films 3a, 3b, 3c... By photoresist and etching, that is, the step of removing the adjacent space portions of the amorphous semiconductor films 3a, 3b, 3c. Will go through.

[0008] However, although the photolithography technique is excellent in fine processing, the amorphous semiconductor film is liable to cause defects in the amorphous semiconductor film due to peeling of the photoresist that defines the etching pattern at pinholes and at the periphery. .

In the prior art disclosed in Japanese Patent Application Laid-Open No. 57-12568, the above-mentioned adjacent distance is provided by burning out a film by laser irradiation. This is extremely effective in solving the above problems. The adjacent distance between the amorphous semiconductor films 3a, 3b, 3c,... Obtained by the photolithography technique is about 600 μm, but in the case of using a laser, the distance can be further reduced.

It should be noted that the use of a laser does not damage other films if they exist under the film portion to be burned out. Otherwise, the target film portion is burned off, and then the unnecessary film below is burned off. The above prior art proposes selecting a laser output and a pulse frequency for each film to satisfy this requirement.

[0011]

However, it is difficult to stabilize the laser output and the pulse frequency. Therefore, considering that the thickness of each film in this type of apparatus is extremely small, the laser The choice of output or pulse frequency to prevent damage to other films is not the best.

[0012]

According to the present invention, there is provided an optical semiconductor device comprising: a transparent conductive film; and a semiconductor film deposited on the conductive film and responsive to light transmitted through the film. At least a part of the unnecessary portion of the semiconductor film is partially irradiated with laser light having a wavelength of 0.6 μm or less, which has a sufficiently low light absorptivity for the transparent conductive film as compared with that for the semiconductor film. And a portion of the transparent conductive film is exposed.

[0013]

According to the present invention, a laser is used. In an optical semiconductor device composed of a superposed body of a transparent conductive film and a semiconductor film, the difference in the light absorptivity of each of these films is focused on and utilized. doing.

FIG. 2 shows the relationship between the light wavelength and the absorptivity of the film. In the figure, the solid line indicates the absorptivity of amorphous silicon, and the broken line indicates the absorptivity of the transparent conductive film (tin oxide film). Represents. Therefore, if the amorphous semiconductor film is irradiated with laser light having a wavelength of 0.6 μm or less to partially remove the amorphous semiconductor film, the absorptivity of the transparent conductive film with respect to the laser light becomes higher than that of the amorphous semiconductor film.
Since it is extremely low , about 1/4 of that for the membrane ,
The transparent conductive film is hardly damaged by the laser irradiation.

[0015]

3A to 3F show a method according to an embodiment of the present invention in the order of steps.

In the step of FIG. 3A, the transparent glass substrate 10 having a thickness of 1 mm to 3 mm
A transparent conductive film 11 made of tin oxide of 00 ° is deposited.

In the step shown in FIG. 3B, the adjacent space portions 11 'are removed by laser beam irradiation, and
a, 11b, 11c,... are formed separately. The laser used has a wavelength of 1.06 μm and an output of 1.3 × 10 ⁸ W /
A YAG laser of cm ² and a pulse frequency of 3 kHz is suitable, and the interval L1 between the adjacent interval portions 11 ′ is set to about 100 μm. Here, the YAG laser uses a high-speed repetitive pulse excitation.
This is the most suitable laser for the electromotive laser. And the light pulse
Average output and peak output should be controlled by repetition frequency
And is effectively used for processing semiconductor devices.

In the step of FIG. 3C, each transparent conductive film 11a,
An amorphous silicon film 12 having a thickness of 5000 to 7000 mm is deposited on the entire surface of the substrate 10 including the surfaces 11b, 11c,. Such a silicon film contains a PIN junction therein parallel to the plane of the film, so that more specifically, a P-type amorphous silicon film is first deposited and then an I-type and N-type amorphous silicon film. The films are sequentially deposited.

In the step shown in FIG. 3D, the adjacent space portions 12 'are removed by laser beam irradiation, and individual amorphous silicon films 12a, 12b, 12c... Are separately formed. Ar laser is suitable as a laser to be used . Ar
The laser oscillates with Ar ion spectrum lines.
Thus, an oscillation line having a wavelength of 0.6 μm or less is output. here
Is a wavelength of 0.51 μm, an output of 2 × 10 ³ W / cm ² , and a CW
Is used, and the interval L2 between the adjacent interval portions 12 'is set to about 300 μm.

At this time, the laser beam finally reaches the transparent conductive film portion 110 located below the adjacent space portion 12 ', but it should be noted that the absorptance of the current wavelength light is shown in FIG. As described above, the transparent conductive film is much lower than the amorphous silicon film. Therefore, if the laser beam is scanned with an irradiation time length almost necessary and sufficient to remove the amorphous silicon film 12 by the film thickness, the amorphous silicon film 12 is completely removed by the film thickness of the amorphous silicon film. Even if the laser beam temporarily hits the transparent conductive film portion 110 temporarily, the portion is hardly damaged.

In the step of FIG. 3E, the transparent conductive film portion 110 is formed.
And the entire surface of the substrate 10 including the surfaces of the amorphous silicon films 12a, 12b, 12c,.
A back electrode film 13 made of aluminum having a thickness is deposited.

In the final step of FIG.
Are removed by laser light irradiation, and the individual back electrode films 13a, 13b, 13c... Are separately formed. The laser used has a wavelength of 1.06 μm and an output of 5 × 10 ⁶ W /
A YAG laser having a pulse frequency of 3 KHz and a cm ² is suitable.

The melting point of aluminum, which is the material of the back electrode film 13, is much lower than that of the transparent conductive film 11.
It should be noted that a laser having an output value sufficiently lower than the laser output used for separating the transparent conductive films 11a, 11b, 11c... Is used. Therefore, when the laser beam is scanned with an irradiation time length almost necessary and sufficient to remove the back electrode film 13 only by its thickness, the back electrode film 13 is completely removed by the thickness of the back electrode film, and as a result, it is temporarily removed. Even if the laser beam hits the transparent conductive film portion 110 directly, the portion is hardly damaged.

When removing such a portion of the back electrode film 13, if a black ink or the like is applied to the surface of the removed portion so as to promote the absorption of the laser beam, the desired portion of the back electrode film 13 can be more reliably ensured. Only one can be removed.

The various configurations and numerical values described in the above embodiments are merely examples, and can be changed as appropriate. For example, an amorphous semiconductor such as amorphous germanium and amorphous silicon nitride and other amorphous semiconductors are used as the semiconductor film, and a tin oxide / indium film or the like is used as the transparent conductive film. Further, for example, the interval between the transparent conductive films 11a, 11b, 11c.
It may be about 0 μm.

[0026]

According to the present invention, when an optical semiconductor device having a transparent conductive film and a semiconductor film deposited thereon is manufactured, partial removal of the semiconductor film by laser is performed by another method. The film can be reliably formed without damaging the film, and the ultrafine processing by laser can be effectively used.

[Brief description of the drawings]

FIG. 1 is a side view showing a typical optical semiconductor device.

FIG. 2 is a characteristic diagram showing light absorption characteristics of a transparent conductive film and a semiconductor film.

FIG. 3 is a sectional view of each step showing an example of the present invention.

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Masaru Takeuchi 2-18-18 Keihanhondori, Moriguchi-shi, Osaka Sanyo Electric Co., Ltd. (56) References JP-A-57-12568 (JP, A) JP-A Sho 52-108780 (JP, A) JP-A-54-120498 (JP, A) JP-A-59-35489 (JP, A) US Pat. No. 4,150,096 (US, A)

Claims (1)

(57) [Claims] In manufacturing an optical semiconductor device comprising a transparent conductive film and a semiconductor film deposited on the conductive film and responsive to light transmitted through the film, at least one of unnecessary portions of the semiconductor film is manufactured. The portion is formed by irradiating laser light having a wavelength of 0.6 μm or less, which has a sufficiently low light absorptivity to the transparent conductive film than that to the semiconductor film, to partially remove only the semiconductor film, A method of manufacturing an optical semiconductor device, wherein a part of the optical semiconductor device is exposed.