JPH03196680A - Manufacture of solar battery - Google Patents

Abstract

PURPOSE:To realize high output and to improve reliability by removing a semiconductor film part on a conducting pattern successively by applying a laser beam to expose a conducting pattern before forming a second electrode and by arranging the second electrode on the semiconductor film including the conducting pattern thereafter. CONSTITUTION:Transference electrode films 2a to 2c as a first electrode are separatedly formed on an insulating substrate 1. Conducting patterns 3ab, 3bc and insulating patterns 4ab, 4bc are formed near one of adjacent interval parts (ab), (bc) of the transference electrodes films 2a to 2c. Then, a semiconductor film 5 is formed on the substrate 1 covering the conducting patterns 3ab, 3bc including the transference electrode films 2a to 2c, the conducting patterns 3ab, 3bc and the insulating patterns 4ab, 4bc. An energy beam is applied to it from the side of an exposed surface to remove a semiconductor film part 5' of an irradiated part successively. The conducting patterns 3ab, 3bc are exposed from semiconductor films 5a to 5c. A rear electrode film 6 as a second electrode is applied onto the semiconductors 5a to 5c including the conducting patterns 3ab, 3bc. Thereby, high output and improved reliability can be realized.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a method for manufacturing a solar cell that generates electricity under sunlight or artificial lighting.

(b) Conventional technology In recent years, solar cells have received a lot of attention as a clean energy source, and in particular, thin film solar cells such as amorphous silicon (hereinafter referred to as a-5i) have lower costs. Because it is advantageous, it is used as a lIk car hole supplement for electric power.
Currently, research is being actively conducted to improve conversion efficiency and reduce costs. Under these circumstances, the light-receiving surface 'I4. One polar film consists of insulating paste and conductive paste!
After screen printing the 8-edge pattern and the conductive pattern, drying, and baking, the above pattern t is irradiated with pulsed laser light to separate the conductive pattern on the insulating pattern.
(Japanese Unexamined Patent Publication No. 62-33477), connection is made using a conductive pattern and a laser, and separation is made by etching (
A method using U.S. Pat. No. 4,724,011) has been developed.

(c) Problems to be Solved by the Invention However, the method of using a laser for connection and etching for separation is disadvantageous in terms of cost reduction because the laser patterning method and etching process are complicated, and it is also difficult to connect with the above two methods. is a high-resistance a-
Due to the presence of the 5i film, if the laser power is too weak, the resistance between the conductive pattern and the back electrode increases, making it impossible to obtain high output and having poor reliability. Furthermore, the laser used for connection is pulsed light and the connection is made at points, so when generating electricity, the current concentrates only in the holes formed by the laser light, so the conductive pattern is damaged by heat generation. Damage may reduce reliability, and conversely, if the laser power is increased, it may penetrate through the conductive pattern and destroy the underlying light-receiving surface electrode film.

The present invention seeks to solve these drawbacks.

(d) Means for Solving the Problems In order to solve the above problems, the present invention provides a plurality of first ! arranging the electrodes, forming a coupling conductive pattern close to one of the adjacent opposing spacing parts of the first electrode, and providing a semiconductor film on the substrate including the conductive pattern and the first electrode; After irradiating the semiconductor film covering the conductive pattern with an energy beam from the exposed surface side and continuously removing the irradiated portion of the semiconductor film to expose the conductive pattern from the conductive film, the conductive pattern is removed. The second electrode is arranged on the semiconductor film including the second electrode.

(E) Function As mentioned above, before forming the second electrode, the semiconductor film portion on the conductive pattern is continuously removed by laser beam irradiation to expose the conductive pattern, and then the semiconductor film including the conductive pattern is removed. By placing the second electrode on the membrane, the second electrode is in continuous direct contact.

(f) Examples Hereinafter, examples in which the manufacturing method of the present invention is applied to a solar cell manufacturing method will be described in detail with reference to FIGS. 1 to 7.

In the process shown in Figure 1, the thickness is l mm -5 mm and the area is 10 mm.
cmX 10cm -5Qcmx 50cm The entire surface of the substrate (1) made of an insulating material such as transparent glass is coated with a layer of tin oxide (SnO) or indium tin oxide (ITO) with a thickness of approximately 2000 to 5000 mm. After a transparent electrode film of a single layer type or a laminated type of transparent conductive oxide (TCO) is deposited, the adjacent spacing parts (ab) and (bc) are removed by irradiation with a laser beam (LB). Then, each transparent monopolar film (2a) (2b) is used as the first electrode.
(2c) - is separated and formed. The laser device used is suitable for a wavelength that is hardly absorbed by the substrate (1), and for the above glass, the wavelength is 0.35 μm to 2 μm.
．． A pulse output type with a wavelength of 5 μm is preferable. Such a preferred embodiment has a wavelength of about 1.06 pm and an energy density of 13 J/
Cm', a Q-switched Nd:YAG laser with a pulse repetition frequency of 3 KHz, and the spacing between adjacent spacing parts (ab) is set to about 50 to 100 μm.

In the process shown in FIG. The conductive pattern (3ab (3bc))... and the insulating pattern (
4ab) (4bc)... are formed in parallel strips, one each. For example, the conductive patterns (3ab) (3b)
cJ... is approximately 1010-207 cm in height by screen printing silver (Ag) paste or other metal paste.
After patterning to an I width of about 100-150 μm,
It is fired at a temperature of about 550°C. Also, the insulation pattern (
4ab) (4bC)... is a material that is formed in a later process and does not diffuse into the amorphous semiconductor film that acts as a semiconductor photoactive layer, such as silicon dioxide (SiO
! ) S+Ot paste made from powder into a paste or other inorganic material is selected, and is printed at a predetermined location to a height of about 110-20p using the same screen printing method as the Ag paste above.
, is patterned to have a width of approximately 100-150 μm, and is similarly fired at a temperature of approximately 550°C.

In this way, the firing temperature of Ag paste and Sin.

When the firing temperatures of the pastes are the same, the firing of both pastes is basically performed in the same manner. However, when firing both at the same time, since both cannot be screen printed at the same time, Ag paste or S10. After screen printing the paste and then pre-baking or pre-drying the paste, it is necessary to screen print the remaining 5iOr paste or Ag paste.

In the process shown in FIG. 3, each transparent electrode film (2a) < 2b) (2
c) ---, 1 conductive pattern (3ab:1j 3 b
C>--- and insulation pattern (4ab) (4bC
)..., an amorphous semiconductor film such as amorphous silicon (a-5i) with a thickness of 4,000 to 7,000 thick, which effectively contributes to charge conversion, is spread over almost the entire surface of the substrate (1), including the surface of the substrate (1). 3) is monosilane (S i H4), disilane (S i ,
The main gas is silicon compound gas such as silicon tetrafluoride (SiF, ), mono-70rosilane (SiH, F), and diborane (B, H6), phosphino (P) (S) for controlling valence electrons as appropriate. It is formed by a plasma CVD method or a photo CVD method in a reaction gas to which a doping gas of . Such a semiconductor film (5) contains a pin junction parallel to the film surface due to the addition of B, H, or PH, and therefore, more specifically, B*H is added to the silicon compound gas.
Furthermore, by adding hydrogenated carbon gas such as methane (CH,) or ethane (C,H,), plasma CVD method or optical
P-type amorphous silicon carbide (a-5
iC) is deposited, then i-type (non-doped) a-5
i and n type a-5i or microcrystalline silicon (μc-5
i) are deposited in a layered manner.

Note that the semiconductor that operates as the semiconductor photoactive layer is a-3 above.
In addition to i-based semiconductors, film semiconductors such as cadmium sulfide (CdS), cadmium telluride (CdTe), and selenium (Se) may also be used, but industrially, the above a-5
i, a-5iC1 and further amorphous silicon germanium <
Preferred are a-5j semiconductors represented by a-5iGe), amorphous silicon tin (a-5iSn), and the like.

In the process shown in FIG. 11, the conductive pattern (3ab) (3
bc) is irradiated with an energy beam such as a laser beam or an electron beam from the exposed surface side of the amorphous semiconductor film (5) covering the semiconductor film portion (5)' of the irradiated area.
is removed continuously, ie, linearly, in the scanning direction of the energy beam. The energy beam used is e.g.
, 06 pm is a laser beam emitted in a pulsed manner from a Q-switched Nd:YAG laser, and the laser beam is scanned so that a portion of the laser pulse overlaps in order to continuously remove the semiconductor film portion (5)°. Ru. The laser beam (LB, ) irradiated at this time is directly irradiated onto the semiconductor film, and the conductive pattern (3ab) (3
bc), even if it has a somewhat large energy density, the transparent conductor in the lower layer is further removed from the film (2a) (2b
) (2c)... cannot be directly hit. As a result, the amorphous semiconductor films (5a) (5b) (5c) are individually divided with the surfaces of the conductive patterns (3ab) (3bc) continuously exposed.

In the process shown in FIG. 5, the semiconductor film (5) and this semiconductor film (
5) Conductive patterns exposed from (3a b) (3bc)
Al, Ti, TiAg on almost the entire surface of the substrate (1) including
A back electrode film (6) as a second electrode of a single layer or a laminated structure made of , Ni, etc. is deposited.

In the final step in FIG. 6, insulation patterns (4ab) (4b
c) Amorphous semiconductor v (5a) located on the surface of...
(5b) A laser beam CL B is applied to the laminate part of the back electrode film (6) from the surface side of this laminate part.
1) is irradiated. Such insulation patterns (4ab) (4b
c)... Laser beam irradiated to the upper layered body part (
LB,) has sufficient energy density to remove such a portion of the stack. That is, the laser beam (L
The laminate portion to which B, ) is irradiated is a back electrode film (6) uniformly connected across a plurality of photoelectric conversion regions (7a) (7b) (7c)... and individual semiconductor films (5a). (5b
) < 5c) in each of the above regions (7a) (7b) (7
c) It is a part that is removed for division drilling every time, and assuming that it has a somewhat large energy density, there is an insulating pattern (with a thickness (height) of 1 minute) directly under the laminate part marked L (
4ab) (4bc)..., the surface of the insulating pattern (4ab) (4bC)... is only slightly removed, and the second laser beam (LBt) of the lower layer
) is prevented from reaching the destination. This second laser beam (LB
By the irradiation of *), separation grooves (8ab) (8bc), . . . that electrically and physically separate the laminate are formed.

As a result, adjacent photoelectric conversion regions (7a) (7b l
(7c) - Back electrode film (6a)C6b)...
and the transparent electrode films (2b), (2c)... are in the above separation groove <
8 a b ) (8 b c ) - Back side tt
L electrode films (6a) (6b) (6c)- are directly coupled via conductive patterns (3ab) (3bc) on the side closer to adjacent spacing #(ab)(bc)... .

When we measured the output characteristics of the solar cells manufactured based on this manufacturing method, we found that the transparent electrode film (2b) (2
c) After laminating the semiconductor film (5) and the back electrode film (6), the upper conductive patterns (3ab) (3bc) and the back electrode film (6a) (6b) of the adjacent charge conversion region are irradiated with a laser beam. Compared to solar cells with a conventional bonded (welded) structure, improvements in fill factor and open circuit voltage were confirmed, and almost the same values for short circuit current were obtained.

As a result, the output power was increased. Such characteristic improvement is
The bonding structure between the conductive pattern and the back electrode film is not indirect due to welding, but is largely due to direct bonding.

FIG. 7 summarizes reliability tests on solar cells manufactured using the manufacturing method of the present invention. The reliability test shows the temporal variation of the output power from the initial value to the output power. Reliability tests include a high temperature test at 90°C, a constant temperature test at 60°C, 95%, a low temperature test at -40°C, and -20°C to 80°C.
This is a temperature cycle test. The reliability test result is -4
In the low-temperature test at 0° C., the output characteristics were improved from the initial values, except that some output characteristics were observed after 1000 hours. It is believed that such improvement in output characteristics is due to an annealing effect based on high temperature treatment.

FIGS. 8 and 9 show other embodiments of the manufacturing method of the present invention. That is, in this example, the insulating pattern made of insulating paste is omitted, and the transparent electrode films (2a) (2b)
On top is a conductive pattern (3ab) made of conductive paste (
3bc)... are formed.

As a result, in the process shown in FIG. 9, selective patterning of the back electrode film cannot be performed by laser beam irradiation, so the back electrode films (6a) (6b) (6c)...
The patterning is carried out at the same time as the film is formed by covering unnecessary parts with a mask. Patterning using a mask method has problems in terms of microfabrication, but the back electrode film (6
a) (6b) <6C)... Even if no microfabrication is performed, the charge conversion region (7a) (,7b
) (7c) - does not reduce the effective area of -.

This method also improved the initial characteristics and yielded high reliability test results.

(g) Effects of the Invention As is clear from the above description, in the present invention, since the second electrode is in continuous direct contact with the conductive pattern, a highly reliable solar cell with high output characteristics can be manufactured.

[Brief explanation of drawings]

1 to 6 show an example of the manufacturing method of the present invention in the order of steps, and FIGS. 1 to 3, 5 and 6 are cross-sectional views,
Figure 4 is a partially sectional perspective view, Figure 7 is a reliability characteristic diagram, and Figure 8 is a reliability characteristic diagram.
9 and 9 are cross-sectional views showing the main steps of another embodiment of the manufacturing method of the present invention.

Claims (1)

[Claims] (1) Arranging a plurality of first electrodes on the insulating surface of the substrate,
A conductive pattern for coupling is formed close to one of the adjacent opposing spacing portions of the first electrode, a semiconductor film is provided on the substrate including the conductive pattern and the first electrode, and a semiconductor film covering the conductive pattern is provided with a conductive pattern for coupling. After irradiating the exposed surface side with an energy beam to successively remove the irradiated portion of the semiconductor film and expose the conductive pattern from the semiconductor film, a second conductive pattern is placed on the semiconductor film including the conductive pattern. A method for manufacturing a solar cell, comprising arranging electrodes.