JPH067600B2 - Method for manufacturing semiconductor device - Google Patents

Description

Detailed Description of the Invention

(A) Field of Industrial Application The present invention relates to a method of manufacturing a semiconductor device using an energy beam such as a laser beam. (B) Conventional Technology As a semiconductor device having a semiconductor film as a photoactive layer, there are solar cells, one-dimensional photosensors, and the like. FIG. 1 shows the basic structure of a solar cell which has been already put into practical use as disclosed in US Pat. No. 4,281,208. (1) is an insulating and transparent material such as glass or heat resistant plastic. Substrate (2a) (2b) (2c) ...
(1) A transparent electrode film deposited on the upper surface at regular intervals, (3a) (3
b) (3c) ... Amorphous semiconductor film such as amorphous silicon overlaid on each transparent electrode film, and (4a) (4b) (4c) ... overlaid on each amorphous semiconductor film. The transparent electrode films (2a) (2b) (2c) ... to the rear electrode films (2a) (2b) (2c) ... The photoelectric conversion region is formed by the respective laminated bodies of 4a) (4b) (4c).
(5a) (5b) (5c) ... Each of the amorphous semiconductor films (3a) (3b) (3c) ... includes, for example, a PIN junction parallel to the film surface therein, and therefore the transparent substrate (1) and the transparent electrode films (2a) (2b). When light is incident through (2c) ..., Photoelectromotive force is generated. Photoelectromotive force generated in each of the amorphous semiconductor films (3a) (3b) (3c) ... Is added in series by the connection with the back electrode films (4a) (4b) (4c). Usually, the photolithography technique, which is excellent in fine workability, is used for the solar cell having such a structure. In the case of this technology, the step of attaching the transparent electrode film on the entire surface of the substrate (1), and the individual transparent electrode film by photoresist and etching.
(2a) (2b) (2c) ... Separation, that is, each transparent electrode film (2
a) (2b) (2c) ... Adjacent interval removal step, deposition of an amorphous semiconductor film on the entire surface of the substrate (1) including the respective transparent electrode films, photoresist and etching Separation of the individual amorphous semiconductor films (3a) (3b) (3c) ..., That is, a step of removing adjacent intervals of the amorphous semiconductor films (3a) (3b) (3c) ... It will be. However, although the photolithography technique is excellent in fine processing, it is easy to cause defects in the amorphous semiconductor film due to the pinholes of the photoresist that defines the etching pattern and peeling at the peripheral edge. The prior art disclosed in Japanese Patent Laid-Open No. 57-12568 is to provide the above-mentioned adjacent intervals by burning off the film by irradiating a laser beam, and to use a photoresist, that is, a wet process, which is necessary for the photolithography technique. The technique which is rich in fine workability is extremely effective in solving the above problems. One thing to keep in mind when using a laser is that such laser processing is essentially thermal processing and does not damage any other film below the part to be processed. is there. Otherwise, the target film portion is burnt out, and even the lower film that is not needed is burnt out, or thermal damage is caused even if it is not burnt out. In order to meet this requirement, the above-mentioned prior art proposes to select a laser output and a pulse frequency for each film. However, the first drawback of the above-mentioned prior art is that in the above-mentioned prior art, after the amorphous semiconductor film is formed, dust and dust adhere to the film surface because the second laser scribing is performed while the film surface is exposed. The scattered substances on the film may be redeposited, increasing the shunt resistance and causing deterioration of the film characteristics. In addition, there is a problem in terms of reliability such as a peeling accident due to humidity and dust in the air. A second drawback is that, in the above-mentioned prior art, after the amorphous semiconductor film is formed, the amorphous semiconductor film is once exposed to the air, so that a step of drawing a vacuum again is required to form the back electrode film. It is necessary to perform the third laser scribing for patterning, which complicates the process. (C) Problems to be Solved by the Invention The present invention eliminates the scribe process of the semiconductor film alone, simplifies the process, and simply connects the first electrode film and the second electrode film,
At the same time, a method for selectively patterning the second electrode film with the semiconductor film is provided. Further, it is intended to prevent an increase in shunt resistance due to adhesion of dust, dust or scattered matter on the upper surface of the semiconductor layer at the time of scribing the semiconductor film and deterioration of the film quality due to moisture or the like. (D) Means for Solving the Problems In order to solve the above-mentioned problems, the manufacturing method of the present invention comprises a plurality of first regions divided into a plurality of regions on the insulating surface of the substrate.
After superposing the semiconductor film and the second electrode film so as to continuously cover the electrode film, the second electrode film and the semiconductor film in the plurality of regions are melted by the irradiation of the first energy beam,
The first electrode film and the second electrode film in different regions are electrically connected to each other via the melt, and the second electrode film on the semiconductor film has a weaker energy density than the first energy beam. The second electrode film is irradiated with the second energy beam in the same official condition as the irradiation of the first energy beam, and the irradiated second electrode film is selectively removed from the semiconductor film, and the second electrode film is divided into a plurality of regions. Each is characterized by being electrically decomposed. (E) Action As described above, by omitting the division step of the semiconductor film alone, the interface state between the semiconductor film and the second electrode film is improved,
At the same time, the patterning of the second electrode film is performed, and the number of manufacturing steps can be significantly reduced. (F) Example An example in which the manufacturing method of the present invention is applied to a method for manufacturing a solar cell will be described in detail below with reference to FIGS. 2 to 8. 2 to 6 show a method of manufacturing a solar cell according to the present invention for each step. In the process of FIG. 2, the thickness 1
mm to 3 mm, 2000 cm to 5 mm on the entire surface of the substrate (10) such as transparent glass having an area of 10 cm x 10 cm to 40 cm x 40 cm.
Transparent electrode film made of 000Å tin oxide (Sno2) (11)
Will be announced. In the process shown in FIG. 3, the adjacent space portion (11) has a laser beam (L
B) is removed by irradiation, and each transparent electrode film (11
a), (11b), (11c) ... Are separated and formed. The laser device used is suitable for a wavelength that is hardly absorbed by the substrate (10), and is 0.35 μm to 2.5 for the above glass.
A pulse output type with a wavelength of μm is preferable. Such a preferred embodiment has a wavelength of about 1.06 μm and an energy density of 13 J / c.
m ² , with pulse repetition frequency 3 KHz N with Q switch
This is a d: YAG laser, and the interval between the adjacent interval parts (11) 'is set to about 100 μm. In the process of FIG. 4, each transparent electrode film (11a) (11b) (11c) ...
Of amorphous silicon (a) having a thickness of 5000 Å to 7000 Å that effectively contributes to photoelectric conversion on the entire surface of the substrate (10) including the surface of
An amorphous semiconductor film (12) such as -Si) is presented. Such a semiconductor film (12) includes a PIN junction parallel to the film surface inside thereof, and more specifically, P-type amorphous silicon carbide is exhibited by a Gero discharge in a silicon compound atmosphere, Then, I-type and N-type amorphous silicon are sequentially stacked. In the step shown in FIG. 5, the semiconductor film (12) ... and the transparent electrode film (11a)
(11b) (11c) ... Including the exposed parts, the entire surface of the substrate (10) has an aluminum single layer structure of about 4000Å to 2 μm or titanium (Ti) or titanium silver alloy (TiAg) on the aluminum. A laminated two-layer structure and a back electrode film (13) in which the two-layer structure is doubly stacked are exhibited. By this step, immediately after the semiconductor film (12) is formed,
Since the back surface electrode (13) is deposited on the entire surface, the semiconductor film
(12) It is possible to prevent dust from adhering to the surface, increase in sheet resistance due to redeposition of scattered matter during scribing, and further to improve the film characteristics of the semiconductor film (12) due to moisture in the oxidizing air. Deterioration can be prevented. In the final step of FIG. 6, in the same step, the photoelectric conversion regions (14a) (14b) (14c) adjacent to each other in series are connected in series and adjacent spaces (1
3) ′ is the first with different split energy densities of the back electrode antinode (13)
It is formed by the irradiation of the second ergi beam (LB1) (LB2). The advantage here is that the processing threshold energy density does not depend on the film thickness. For example, FIG. 7 shows the analysis of the absorption rate (A) and the reflectance rate (R) of the film thickness dependency when the back electrode film (13) having a single-layer aluminum structure is irradiated with a laser beam having a wavelength of 1.06 μm. Is. From this analysis result, the back electrode film (1
Absorption rate for laser beam of wavelength 1.06μm in 3)
It can be seen that although (A) is a low rate of less than 10%, it does not depend on the film thickness. That is, the serial connection portion is irradiated with the first laser beam (LB1) with an increased power to melt the back electrode film (13) and the semiconductor film (12) at the same time, and a conductive silicide alloy film ( 15), and the transparent electrode films (11b) (11c) ... and the back surface electrode film (13) that were present at the irradiation position of the first laser beam (LB1) and were dividedly arranged through the alloy film (15) And are electrically connected. Simultaneously with the scanning process of the first laser beam (LB1), the second laser beam (LB) whose energy density is reduced
2) is used to separate the back electrode film (13) into individual photoelectric conversion regions (14
a) (14b) (14c) ... Divide by each. The energy density of the first and second laser beams (LB1) (LB2) can be easily changed by changing the focus position or the attenuator that adjusts the spot diameter of the first and second laser beams (LB1) (LB2). You can In this way, the back electrode film (13a) (1
3b) ... and the transparent electrode films (11b) (11c) ... are electrically connected, and in the same process, the adjacent gaps (13) 'of the back electrode film (13) are removed by irradiation with the laser beam (LB2). As a result, individual back surface electrode films (13a) (13b) (13c) ... Are formed. As a result, the back surface electrode films (13a) (13b) of the photoelectric conversion regions (14a) (14b) (14c) ... and the transparent electrode films (11b) (11c) ...
And are combined in the adjacent space, and the photoelectric conversion region (14
a), (14b), (14c), ... Are electrically connected in series through the alloy film (15). The first and second laser beams (LB1) and (LB2) are one laser beam (L1) emitted from the same laser source.
A method of dividing B) into two having different energy densities and a method of using individual laser sources can be adopted, but a slight supplementary explanation will be added to the dividing method with reference to FIG. A laser beam (LB) emitted from the same laser source is guided to a beam splitter (BS), where the first laser beam (LB) is transmitted through the beam splitter (BS).
1) and a second laser beam (LB2) that reflects the light is split into two. At this time, the first laser beam (LB1) and the second laser beam (LB1)
Laser beam (LB2) of the backside electrode film (13a) (13b)
When the intensity of the first energy beam (LB1) is set to 1 on the basis of the intensity ratio determined by the film thickness, the material, etc., the intensity of the second energy beam (LB2) is 0.5.
The beam splitter (B
The first energy beam (LB1) transmitted through S directly reaches the condenser lens (FL), and the second energy beam (L1)
B2) reaches the condenser lens (FL) via the two mirrors (M1) and (M2). Then, a condensing lens (FL) is used for series connection and alloying and second electrodes (13a) (13b) ...
Is adjusted to the energy density required for selective removal for electrical division of the, and at the same time, the adjacent processed portions are irradiated. The first and second laser beams (LB1) (LB2)
The laser beams (LB1) and (LB2) may be scanned during the irradiation of, but the configuration in which the stage on which the workpiece is mounted moves is more suitable for large-scale processing, The workpiece side is configured to move. (G) Effect of the Invention According to the manufacturing method of the present invention, as is the case with lye, the second electrode film is formed immediately after the semiconductor film is formed on the entire surface of the divided first electrode film, and the adjacent second electrode film is formed. As a means for electrically connecting the semiconductor film, a strong first energy beam is used to irradiate the second electrode film to melt the second electrode film and the semiconductor film, and thus the first electrode film and the second electrode film. Since the second electrode is patterned by using the weak second energy beam in the same process, the process can be simplified and an inexpensive manufacturing method can be provided.
Since there is no patterning step in which the surface of the semiconductor film is directly exposed, the state of the interface between the semiconductor film and the second electrode film can be improved.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a typical example of a solar cell, FIGS. 2 to 6 are cross-sectional views showing steps of manufacturing a solar cell according to an embodiment to which the method of the present invention is applied, and FIG. FIG. 8 is a characteristic diagram showing the dependence of the optical characteristics of the back electrode film on the film thickness of the back electrode film, and FIG. 8 is a schematic diagram of an embodiment relating to a laser beam splitting method. (10) ... Substrate, (11a) (11b) (11c) ... Transparent electrode film, (1
2) (12a) (12b) (12c) ... a-Si based semiconductor film, (13)
(13a) (13b) (13c) ... Back electrode film, (14a) (14b)
(14c) ... Photoelectric conversion region, (15) ... Silicide alloy film,
(BS) ... Beam splitter, (LB1) (LB2) ...
First and second laser beams.

Claims (3)

[Claims] 1. A semiconductor film and a second electrode film are overlapped and deposited to continuously cover a plurality of first electrode films divided into a plurality of regions on an insulating surface of a substrate, and then the plurality of regions are applied to the plurality of regions. At this time, the second electrode film and the semiconductor film are melted by the irradiation of the first energy beam, and the first region of a different region is melted through the melt.
While electrically connecting the electrode film and the second electrode film, a second energy beam having a weaker energy density than the first energy beam is applied to the second electrode film on the semiconductor film by the first energy beam. In the same process as the beam irradiation, the irradiated second electrode film is selectively removed from the semiconductor film, and the second electrode film is electrically decomposed into a plurality of regions. Of manufacturing a semiconductor device. 2. The method of manufacturing a semiconductor device according to claim 1, wherein the first and second energy beams are formed by dividing energy beams emitted from the same energy source. 3. The method of manufacturing a semiconductor device according to claim 1, wherein the first and second energy beams are emitted from individual energy sources.