JPH053752B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Industrial Application Field The present invention relates to a method for manufacturing a photovoltaic device using a semiconductor film as a photoactive layer.

(b) Conventional technology Figure 2 shows the basic structure of a solar cell that has already been put into practical use. 1 is an insulating and transparent substrate made of glass, heat-resistant plastic, etc.; 2a, 2b, 2;
c... are transparent conductive films deposited on the substrate 1 at regular intervals; 3a, 3b, 3c... are amorphous semiconductor films such as amorphous silicon deposited on each transparent conductive film,
4a, 4b, 4c... are superimposed and deposited on each amorphous semiconductor film, and the transparent conductive films 2b, 2c on the right side of each
It is a back electrode film that can be partially overlapped with...

Each amorphous semiconductor film 3a, 3b, 3c... includes, for example, a PIN junction parallel to the film surface inside thereof, and therefore the transparent substrate 1 and the transparent conductive film 2a, 2b, 2c...
When light is incident sequentially through..., a photovoltaic force is generated. The photovoltaic force generated within each amorphous semiconductor film 3a, 3b, 3c... is the back electrode film 4a, 4b, 4c.
are added in series by the connection at .

In such a device, one factor that influences the light utilization efficiency is the total amount of amorphous semiconductor films 3a, 3b, 3c, etc. that actually contribute to power generation, relative to the light receiving area (i.e., substrate area) of the entire device. It is the proportion of the area. However, each amorphous semiconductor film 3a, 3b,
A region without an amorphous semiconductor (a region indicated by the symbol NON in the figure) that inevitably exists between adjacent regions 3c... reduces the above-mentioned area ratio.

Therefore, in order to improve the light utilization efficiency, first, the distance between adjacent transparent conductive films 2a, 2b, 2c, etc. is reduced,
Then, the distance between adjacent amorphous semiconductor films 3a, 3b, 3c, . . . must be reduced. Such a reduction in spacing is determined by the processing accuracy of each film, and therefore, conventionally, photo-etching technology, which has excellent precision processing properties, has been used. In the case of this technique, a step of depositing a transparent conductive film on the entire surface of the substrate 1, and each individual transparent conductive film 2a, 2b, 2c by photoresist and etching are performed.
Separation of..., that is, each transparent conductive film 2a, 2b, 2c
..., the step of depositing an amorphous conductor film on the entire surface of the substrate 1 including on each of these transparent conductive films, and the step of removing each individual amorphous semiconductor film 3a, by photoresist and etching. 3b, 3c..., that is, each amorphous semiconductor film 3a, 3b, 3c...
The step of removing the adjacent spaced portions is sequentially performed.

However, although photo-etching technology is excellent in terms of fine processing, it tends to cause defects in the amorphous semiconductor film due to pinholes or peeling at the periphery of the photoresist that defines the etching pattern.

The prior art disclosed in Japanese Unexamined Patent Publication No. 12568/1985 creates the above-mentioned adjacent spacing by burning out the film by laser beam irradiation, and does not use any photoresist, that is, a wet process, which is necessary for photolithography. This technique, which has excellent precision processing properties, is extremely effective in solving the above problems.

On the other hand, as shown in FIG.
Immediately before dividing the amorphous semiconductor film 3 successively deposited on the semiconductor films 3 into each element 5a, 5b, etc., a back electrode film 41 is preliminarily deposited on the entire surface of each of the semiconductor films 3. A manufacturing method including a process was proposed. That is, if the back electrode film is deposited after the step of dividing the amorphous semiconductor film 3, dust or moisture from photo-etching may be present at the bonding interface between the two, and such inclusions may be removed. It is possible to suppress the peeling and corrosion accidents of the back electrode films 4a and 4b that have occurred as a cause.

However, when attempting to finely process a laminate in which the back electrode film 41 is adhered to the amorphous semiconductor film 3 using the laser beam described above, the following problem occurs. FIG. 4 is an enlarged view of a main part showing an example of a conventional photovoltaic device to explain such a situation. By irradiating the semiconductor film 3 and the first back electrode film 41 with a laser beam to divide the semiconductor film 3 and the first back electrode film 41 into regions 5a, 5b, . When attempting to do so, residues 7, 7, etc. of the melted amorphous semiconductor film may remain in the vicinity of the removed portion in the adjacent spaced portion 6, or may not be removed accurately in a predetermined pattern. There was a fear that the residues 7, 7, . . . due to unremoved Zuko remained especially on both sides of the laser beam in the scanning direction. The residues 7, 7... remaining on both side surfaces are generated as a result of a low energy distribution on both sides of the adjacent gap because the energy density distribution in the laser beam is slightly normal. Conceivable.
Whatever the cause, if the residues 7, 7... are present in the adjacent spaces to be removed, the second back electrode film 42 deposited in the step of FIG. 5 will be free of such residues 7, 7...
Therefore, in the process shown in FIG. 6, the adjacent spacing portions 6' are removed by laser beam irradiation, and the adjacent spacing portions 6', which are supposed to be connected in series, are removed. The second back electrode films 42a, 42b... and the transparent conductive films 2b, 2c...
As a result of the presence of the residues 7, 7, etc., or the formation of gaps 8, the adhesive strength between the two decreases, and finally the back electrode 4
a, 4b, etc. may peel off, resulting in a decrease in manufacturing yield.

Furthermore, even if fine processing using a laser beam can be performed well, in the case of an element structure such as that shown in FIG. 2, although it is possible to reduce the ineffective area that does not contribute to photoelectric conversion, The back electrode films 4a, 4b... of the photoelectric conversion elements 5a, 5b on the left are in the dividing grooves 7, 7... of the transparent conductive films 2a, 2b, 2c... on the right side of the photoelectric conversion elements 5a, 5b.
..., the insulation interval _W1 between the adjacent transparent conductive films 2a, 2b, 2b, 2c, ... is increased by the embedding of the back electrode films 4a, 4b... The distance W ₂ between the films 4a, 4b, . . . and one of the transparent conductive films 2a, 2b, . Such a reduction in the insulation interval causes leakage current to occur between the transparent conductive films 2a, 2b, 2b, 2c, . . . .

On the other hand, adjacent photoelectric conversion elements 5a, 5b, 5c
...Transparent conductive film 2 to electrically connect them in series
When a laser beam is used in the step of exposing the semiconductor film 3, that is, the step of removing at least the semiconductor film 3, the semiconductor film 3 can be narrowly removed and the transparent conductive films 2b, 2c, etc. can be exposed. can be reduced.

However, the exposed portions of the transparent conductive films 2b, 2c...
b, 5c... It is a part used for connecting with each other,
If this exposed length becomes narrower, a predetermined exposed length is required because the series resistance component in such a connection portion increases. Therefore, if a laser beam capable of reducing the removal width is used, it may be necessary to perform multiple scans in order to obtain a predetermined exposure length, which reduces work efficiency.

(c) Problems to be solved by the invention Therefore, in the case of the photovoltaic device shown in FIG. 3, the amorphous semiconductor 3 and back electrode 41 of each photoelectric conversion element 5a, 5b... By adhering the transparent conductive films 2a, 2b, 2c, etc. of the respective elements 5a, 5b, etc., the amorphous semiconductor can be prevented from intervening at the bonding interface. Although this has the advantage of reducing leakage current between each element, it is difficult to perform sufficiently fine processing using a laser beam as described above.

Therefore, an object of the present invention is to control the generation of leakage current due to conventional embedding of the back electrode film through a step of successively depositing the amorphous semiconductor and the back electrode film. Even when patterning methods using the above-mentioned laser beam or other energy beams such as electron beams are adopted, the formation of residues can be suppressed and effective electrical connections can be easily obtained on the transparent conductive film. An object of the present invention is to provide a method for manufacturing a power device.

(d) Means for Solving the Problems In order to solve the above-mentioned problems, the present invention provides a light-transmitting first layer in a plurality of regions on one main surface of a light-transmitting substrate.
A photoelectric conversion element in which an electrode film, a semiconductor film, and a second electrode film are laminated in this order is arranged in a divided manner, and these photoelectric conversion elements are electrically connected in series through a third electrode film at an adjacent interval between the elements. A method for manufacturing an integrated photovoltaic device, wherein the laminate of the semiconductor film and the second electrode film is formed by applying energy from the other main surface of the substrate onto the first electrode film in the adjacent spaced portion. a step of removing by beam irradiation, dividing into each region and exposing a part of the first electrode film for series connection; and a second electrode film of the photoelectric conversion element adjacent to the exposed part of the first electrode film. a step of providing a third electrode film on the exposed surface including the third electrode film, and the third electrode film is connected to the second electrode film of one adjacent photoelectric conversion element and the entire exposed part of the first electrode film of the other photoelectric conversion element. In the bonded state, the stack of the third electrode film, second electrode film, and semiconductor film of the other photoelectric conversion element in the vicinity of the bonded portion is removed by irradiation with an energy beam from the other principal surface; The method is characterized by comprising the step of electrically connecting one photoelectric conversion element and the other photoelectric conversion element in series.

(E) Effect As mentioned above, the laminate of the semiconductor film and the second electrode film has the following properties:
When the first electrode film in the adjacent space is removed by irradiation with an energy beam, the semiconductor film fills the dividing groove formed between the first electrode films, and the insulation between the first electrode films increases. It is possible to avoid the risk of a conductor entering the gap and reducing the insulation gap, and the irradiation part of the energy beam is on the first electrode film at the electrical connection point of the adjacent photoelectric conversion element, and the exposed part is effectively used. It can be used for the above electrical connection.

Furthermore, when removing the laminate, the energy beam is irradiated from the other main surface of the substrate, which makes it possible to suppress the formation of residues.

(F) Embodiment FIG. 1 is an enlarged cross-sectional view of the main parts of a photovoltaic device manufactured by the manufacturing method of the present invention, and shows an adjacent spacing section 6 that electrically connects two photoelectric conversion elements 5a and 5b in series. It is mainly depicted. That is, transparent conductive films 2a, 2 which control the first electrode film are formed in a plurality of regions on one main surface of the substrate 1 having insulating and light-transmitting properties.
b..., amorphous semiconductor films 3a, 3b... having PIN junctions parallel to the film surface, and first back electrode films 41a, 41b... that control the second electrode film are laminated in this order. The photoelectric conversion elements 5a, 5b... are arranged in a divided manner, and the photoelectric conversion elements 5a, 5b...
5b... is the adjacent spacing section 6 between the elements 5a and 5b.
are electrically connected in series. As is clear from FIG. 1, the electrical series connection of the photoelectric conversion elements 5a, 5b, _. Tin oxide, separated by a dividing groove 7 having a
Transparent conductive films 2a, 2b, .
The dividing groove 7 between the transparent conductive films 2a, 2b...
... is buried by the semiconductor film 3a constituting the photoelectric conversion element 5a on one side (the one on the left), extends onto the transparent conductive film 2b on the other side (the one on the right), and is exposed by irradiation with an energy beam such as a laser beam. On the other transparent conductive film 2b, a first back electrode film 41 is applied over the laminate of the semiconductor film 3a of the one photoelectric conversion element 5a and the first back electrode film 41a.
This is realized by extending the second back electrode film 42a, which together with a forms the back electrode film 4a and controls the third electrode film.

The semiconductor film 3a constituting one photoelectric conversion element 5a is embedded in the dividing groove 7 of the transparent conductive films 2a and 2b, and the transparent conductive film 2 of the other photoelectric conversion element 5b is
The manufacturing method of the photovoltaic device of the present invention up to step b will be described in detail with reference to FIGS. 7 to 9. Before the step shown in FIG. 7, the steps shown in FIG. be done. That is, in the process shown in FIG. 3, monomers such as tin oxide, indium tin oxide, etc., which have been divided into photoelectric conversion elements 5a, 5b, etc., are already formed on one main surface of the insulating and translucent substrate 1. An amorphous silicon-based amorphous semiconductor film 3 and a first back electrode film 41 are deposited so as to continuously cover the transparent conductive films 2a, 2b, . . . having a layered or laminated structure. More specifically, when the amorphous semiconductor film 3 is made of hydrogenated amorphous silicon and has a PIN junction parallel to the film surface from the light incident side, it is first exposed to a silicon compound atmosphere, such as a silane (SiH ₄ ) gas atmosphere. A P-type layer with a thickness of about 50 Å to 200 Å is formed by adding diborane (B ₂ H ₆ ) containing P-type determining impurities and causing glow discharge, and then sequentially increasing the thickness using only SiH ₄ gas.
An intrinsic (I-type) layer with a thickness of about 4000 to 6000 Å and an N-type layer with a thickness of about 100 to 500 Å made by adding phosphine (PH ₃ ) containing an N-type determining impurity to SiH ₄ gas are deposited. After forming such an amorphous semiconductor film 3, a thickness of 2000 Å to 1 μm is applied to prevent dust from adhering to the semiconductor film 3.
A first back electrode film 41 made of aluminum (Al) with a thickness of about 100 m is immediately deposited.

In the process shown in FIG. 7, adjacent photoelectric conversion elements 5a, 5
Adjacent interval portion 6... where series connection of b... is performed.
amorphous semiconductor film 3'... and first back electrode film 4
1' is removed by laser beam irradiation from the other main surface side of the substrate 1 as indicated by the arrow, and the individual amorphous semiconductor films 3a, 3b... and first back electrode films 41a, 41b... are removed. Each photoelectric conversion element 5a, 5
It is divided and formed for each b... The laser used is, for example, Nd with a wavelength of 1.06 μm and a pulse frequency of 3 KHz:
It is a YAG laser, and its energy density is 2×
The laser beam diameter is adjusted as much as possible to 10 ⁷ W/cm ² . By irradiating this laser beam, the distance _L1 between the adjacent spacing parts 6 is set to about 300 μm to 500 μm.

The irradiation direction of the laser beam is on the exposed surface side of the adjacent gap portion 6 to be removed,
In other words, it is not from the first back electrode film 41' side, but from the other main surface side of the substrate 1 as much as possible from the amorphous semiconductor film 3'... side which is the adhesion interface side with the transparent conductive films 2a, 2b... has been done. Then, the laser beam embeds the semiconductor film 3a of one of the photoelectric conversion elements 5a in the dividing groove 7 of the transparent conductive films 2a and 2b, and extends the end thereof onto the other transparent conductive film 2b. The amorphous semiconductor film 3' on the transparent conductive film 2b located in the adjacent interval 6 is irradiated.

In the subsequent step shown in FIG. 8, the first back electrode is divided into a plurality of photoelectric conversion elements 5a, 5b, . Membranes 41a, 41b...
In order to continuously cover the exposed transparent conductive films 2a, 2b, etc. in the upper and adjacent spaces 6, titanium (Ti) or titanium silver (TiAg) with a thickness of several 1000 Å and a film of several 1000 Å thick are applied. Al and further film thickness number
A second back electrode film 42 having a three-layer structure of Ti or TiAg with a thickness of 1000 Å to 5000 Å is deposited in an overlapping manner. The first and third layers of Ti or TiAg prevent corrosion of the underlying Al layer due to moisture and facilitate laser processing in the next process. The layers reduce series resistance.

In the final step in FIG. 9, the other photoelectric conversion element 5
The second back electrode film 42, which also completely covers the exposed portion 8 of the transparent conductive film 2b, is divided to electrically connect the individual photoelectric conversion elements 5a, 5b in series. This division of the second back electrode film 42 is such that the back electrode film 42a of the photoelectric conversion element 5a on the left and the exposed portion 8 of the transparent conductive film 2b of the photoelectric conversion element 5b on the right are completely combined. , is performed on the right-adjacent photoelectric conversion element 5b in the vicinity of the coupling portion together with the first back electrode film 41b. Specifically, by irradiating the laminated body of the second back electrode film 42, the first back electrode film 41b, and the semiconductor film 3b of the right-adjacent photoelectric conversion element 5b in the vicinity of the coupling portion with a laser beam, these The laminate is removed, and individual second back electrode films 42a, 42b, . . . are formed. As a result, the photoelectric conversion elements 5a, 5b, . . . are electrically connected in series. The laser beam is irradiated from the other main surface side of the substrate 1 as shown by the arrow. For example, the laser used when irradiating the semiconductor film 3 and the first back electrode film 41 from the other main surface side of the substrate 1 is a Nd:YAG laser, and the energy density at that time is approximately 3×10 ⁷ W/ ^cm2 .

(G) Effects of the Invention As is clear from the above description, in the method for manufacturing the photovoltaic device of the present invention, the laminate of the semiconductor film and the second electrode film constituting one of the adjacent photoelectric conversion elements is Since the first electrode film is removed by irradiation with the energy beam, the semiconductor film fills the dividing groove formed between the first electrode films,
It is possible to reliably avoid the risk of the conductor entering into the dividing groove and reducing the insulation interval, and it is possible to reduce the leakage current between the first electrode films.

Furthermore, since the portion of the stacked body of the semiconductor film and the second electrode film that is removed by the energy beam irradiation is on the first electrode film at the electrical connection point of the adjacent photoelectric conversion elements in the adjacent spacing, the energy beam is removed. The parts removed and exposed by the beam irradiation can be effectively used for the above-mentioned electrical connections, and as a result, the energy beam is not irradiated to unnecessary areas and the number of times the energy beam is scanned can be minimized. can. Furthermore, electrical separation of the third electrode film that electrically couples adjacent photoelectric conversion elements is performed using an energy beam, but is not performed on the third electrode film alone, but on the stacked structure of the second electrode film and the semiconductor film. Therefore, there is no need for selective machining with strict machining conditions, and therefore, the number of scans of the energy beam can be reduced, and workability can be improved.

In addition, according to the manufacturing method of the present invention, when removing the laminate by irradiating the energy beam, the energy beam is irradiated from the other main surface side of the substrate, so it is possible to suppress the formation of residues. This makes it possible to prevent peeling accidents of the back electrode film.

[Brief explanation of drawings]

FIG. 1 is an enlarged sectional view of essential parts showing one embodiment of an integrated photovoltaic device manufactured by the manufacturing method of the present invention, FIG. 2 is a sectional view of a conventional device, and FIGS.
The figure shows an enlarged cross-sectional view showing each step of the method for manufacturing a conventional device, and FIGS. 7 to 9 show enlarged cross-sectional views of main parts showing each step of the method for manufacturing the integrated photovoltaic device of the present invention. . 1... Substrate, 2a, 2b, 2c... Transparent conductive film, 3, 3a, 3b, 3c... Semiconductor film, 41,
41a, 41b...first back electrode film, 42, 42
a, 42b...second back electrode film, 5a, 5b, 5
c...Photoelectric conversion element.

Claims (1)

[Claims] 1. A photoelectric conversion element in which a transparent first electrode film, a semiconductor film, and a second electrode film are laminated in this order in a plurality of regions on one principal surface of a transparent substrate is arranged in a divided manner. and a method for manufacturing an integrated photovoltaic device in which these photoelectric conversion elements are electrically connected in series via a third electrode film at adjacent intervals between the elements, the semiconductor film and the second electrode film being The laminate is removed by irradiating an energy beam from the other main surface of the substrate on the first electrode film in the adjacent spaced portion, and the first electrode is divided into each region and connected in series. a step of exposing a portion of the film; a step of providing a third electrode film on an exposed surface including a second electrode film of the photoelectric conversion element adjacent to the exposed portion of the first electrode film; and a step of providing the third electrode film, In a state where the second electrode film of one adjacent photoelectric conversion element is connected to the entire exposed part of the first electrode film of the other photoelectric conversion element, the third electrode film of the other photoelectric conversion element near the joint part is connected to the second electrode film of the other photoelectric conversion element.
removing the laminate of the electrode film, the second electrode film, and the semiconductor film by irradiating the other main surface with an energy beam, and electrically connecting one photoelectric conversion element and the other photoelectric conversion element in series; , A method for manufacturing an integrated photovoltaic device, comprising: