JP2598936B2 - Method for manufacturing photovoltaic device - Google Patents

Description

The present invention relates to a method of manufacturing a photovoltaic device used as a power source for small consumer electronic devices such as calculators and watches.

(B) Conventional technology A photovoltaic device in which photoelectric conversion elements are provided in a plurality of power generation regions on an insulating surface of a substrate and the photoelectric conversion elements are electrically connected in series is disclosed, for example, in Japanese Patent Publication No. 58-21827. It is already known and has been put into practical use as a power source for small consumer electronic devices such as the above-mentioned calculators. A general requirement for a photovoltaic device is to reduce the price per unit of power generation, which is achieved by increasing the photoelectric conversion efficiency and reducing the manufacturing cost.

However, the photovoltaic device used as a power source for the above-mentioned small consumer electronic devices has been reduced in power consumption, such as an LSI constituting a drive circuit of a load, as compared with that used for photovoltaic power generation. At present, it is possible to operate electronic devices sufficiently with the power generation output under the following room light,
Rather than increasing the photoelectric conversion efficiency, the demand for the manufacturing cost is strict.

In the manufacture of the photovoltaic device disclosed in the above prior art, the first electrode film, the semiconductor film, and the second electrode film constituting the photoelectric conversion element must be covered with a metal mask at a place where they should not be adhered at the time of formation. By using the masking method of covering with, the manufacturing process is simplified and the manufacturing cost is reduced.

However, according to such a masking method, when a film is formed for each photoelectric conversion element, when the substrate is in a heated state, the film exudes (bleeds) at the film periphery peculiar to the masking method.
Occurs, a predetermined fine fine pattern cannot be obtained, and if the photoelectric conversion elements do not have a sufficient interval length between adjacent adjacent portions, for example, the photoelectric conversion elements are in an adjacent relationship and the second There is a danger of short circuit between the electrode films. In particular, when a light-transmitting conductive oxide (hereinafter referred to as TCO) typified by ITO or SnO ₂ is used to make the second electrode film a light incident surface, a suitable film formation of the second electrode film of the TCO is performed. Substrate 200
Since the temperature must be maintained at a temperature of at least 0 ° C., the metal mask will undergo significant linear expansion in such a high temperature state, and the exudation of the film at the periphery of the film will not be sufficient without sealing the area where the mask must be performed. As a result, the occurrence of a short circuit accident between the second electrode films becomes remarkable. Also TCO 2
Since the electrodes are translucent, it is difficult to visually determine even if a short circuit accident has occurred. Then, as a result of being located between the photoelectric conversion elements, the adjacent space to be further viewed forms an ineffective region that does not contribute to photoelectric conversion, and is as narrow as possible in order to reduce the ratio of the effective power generation region to the light receiving area. Must be done, which is inconsistent with the avoidance of short-circuit accidents.

As is well known, there is a photolithography method as a method for processing a film into a predetermined fine fine pattern, but the photolithography method involves coating, baking, exposing, developing, etching, and applying a photoresist. It must go through a series of complicated steps such as peeling,
It is not suitable for manufacturing a photovoltaic device used as a power source of a small-sized consumer electronic device which requires a low price because it causes an increase in manufacturing cost.

The method of manufacturing a photovoltaic device disclosed in Japanese Patent Application Laid-Open No. 59-35487 uses a masking method on an insulating surface of a substrate (1) as shown in FIG.
First, the first electrode film (3) is not divided for each (2d).
Is formed, and then the semiconductor film (4) and the second electrode film (5) are successively superimposed and deposited on the first electrode film (3) without being divided, using a mask dedicated to each film. As shown in FIG. 7, the photoelectric conversion elements (7a) to (7a)
In order to divide d), their adjacent intervals (ab) (bc) (c
d) is irradiated with a laser beam (LB). That is, a laser beam (LB) is irradiated to each film of the adjacent interval portions (ab), (bc), and (cd), and each photoelectric conversion element (7
The technique of trying to divide a) to (7d) is extremely disadvantageous in solving the drawbacks of the conventional technique of patterning adjacent spaces (ab) (bc) (cd) by a masking method or a photolithography method. It is informative.

However, the patterning of the adjacent gaps (ab), (bc), and (cd) by the irradiation of the laser beam also has a problem as shown in FIGS. 8A and 8B. That is, when the second electrode film (5), the semiconductor film (4) and the first electrode film (3) located in the adjacent space (ab) are simultaneously removed by laser beam irradiation, the adjacent space ((ab)) is removed. In ab), the opposing side faces of the adjacent photoelectric conversion elements (7a) and (7b) are the first.
In order for the electrode film (3a) (3b), the semiconductor film (4a) (4b) and the second electrode film (5a) (5b) to be exposed,
As shown in FIG. 8 (A), a residue (8) during laser processing is generated in the adjacent space (ab), and if this is a conductor, the same photoelectric conversion element (7a), (7b) exposed ), The first electrode films (3a) and (3b) and the second electrode films (4a) and (4)
b) undesirably binds. FIG. 9 (B)
The semiconductor film portion irradiated with the peripheral portion of the laser beam (LB) is annealed and micro-crystallized or crystallized because the peripheral portion of the laser beam (LB) does not have enough energy to remove it. As a result, low resistance layers (9) and (9) are formed, and the same photoelectric conversion elements (7a) and (7) are formed.
b) may cause a short circuit.

(C) Problems to be Solved by the Invention As described above, in the conventional manufacturing method, if the manufacturing cost is reduced by using the masking method, it does not contribute to the short circuit accident between the second electrode films or the photoelectric conversion. The ineffective area is increased, the manufacturing cost cannot be reduced by the photolithography method, and the patterning using a laser beam also involves a short circuit accident. Therefore, the present invention is to solve the above problems of the conventional manufacturing method at the same time.

(D) Means for Solving the Problems In order to solve the above problems, the present invention provides, for each of a plurality of power generation regions on an insulating surface of a substrate, an extended portion extending from the power generation region toward the periphery of the substrate. A semiconductor film including a photoactive layer on a first electrode film in a power generation region and on an insulating surface at an adjacent space between the first electrode films except for the above-mentioned first electrode film extension portion; And the first of the adjacent power generation regions exposed from the semiconductor film.
A second electrode having an extended portion extending on the electrode film extended portion is laminated on the semiconductor film including the adjacent interval portion, and further covers at least the second electrode film for each power generation region and the extended portion to form the adjacent interval. After selectively forming a protective film for exposing the second electrode film portion located in the portion by using a masking method at a temperature lower than the film forming temperature of the semiconductor film and the second electrode film, the protective film is used as a mask. The second exposed at the adjacent space portion
The electrode film portion is etched, and the second electrode film is divided for each power generation region.

Further, the etching of the second electrode film portion at the adjacent interval using the protective film as a mask is performed by removing at least a part of the semiconductor film portion exposed by removing the second electrode film portion from the exposed surface side toward the substrate. Removing step.

(E) Function In the case where the division of the second electrode film formed on the semiconductor film is used by etching without being divided for each power generation region as described above, the deposition temperature of the second electrode film and the semiconductor film is used. By using the protective film selectively formed using the masking method at a lower temperature as a mask, the protective film is formed in a low temperature state despite being formed by the masking method. As a result of suppression of exudation, even if the width of the adjacent space is reduced, the second electrode exposed in the adjacent space can be reliably removed.

(F) Embodiment FIGS. 1 to 5 are for explaining the manufacturing method of the present invention. First, in the step of FIG. 1, an insulating material such as glass, ceramic, polymer film or the like is insulated. A plurality of power generation areas (2a) to (2d) are aligned on one main surface (1a) of the rectangular substrate (1) made of the treated metal and aligned in the long side direction of the main surface (1a). First electrode film to be formed (3a)
To (3d) are divided and arranged. Such a first electrode film (3a)-
(3d) When the substrate (1) is on the back side, a single layer or a laminated structure composed of aluminum (Al), titanium silver alloy (TiAg), silver (Ag) metal, It has a laminated structure whose surface is covered with the above TCO and a substrate (1)
Extension of the long side of one of the long sides (3ae)
(3de) are provided, and the extended portions (3ae) to (3ce) of the first electrode films (3a) to (3c) having the first electrode films (3b) to (3d) divided on the right side are: First electrode film (3b) on the right
It is patterned in an L-shape bent toward (3d). When the first electrode films (3a) to (3d) are formed, the island-shaped region (3t) that operates as an output extraction terminal together with the extension (3de) of the right end first electrode film (3d) is formed on the left end first. It is provided close to the electrode film (3a).

In the step of FIG. 2, the peripheral portion of the substrate (1) including the extended portions (3ae) to (3de) of the first electrode films (3a) to (3d) is covered with a metal mask, and the second exposed from the mask. On the first electrode films (3a) to (3d) and their first electrode films (3a) to (3d)
Adjacent space (ab), (bc), (cd) insulated surface
Amorphous silicon, amorphous silicon carbide, amorphous silicon germanium, microcrystalline silicon, etc. are appropriately formed by a plasma CVD method or a photo CVD method using a silicon compound gas such as H ₄ , Si ₂ H ₆ , SiF ₄ as a main source gas. The semiconductor film (4) including the pin-type, pn-type, pi-type, or tandem-type semiconductor photoactive layer disposed in each layer is obtained by heating the substrate (1) to about 200 to 300 ° C. It is formed.

In the step of FIG. 3, the above-mentioned adjacent space portions (ab), (b)
c) Like the semiconductor film (4) which is continuously arranged without removing (cd), without dividing the power generation regions (2a) to (2d) on the semiconductor film (4). A second electrode film (5) is provided. Although the second electrode film (5) is not divided for each of the power generation regions (2a) to (2d), when divided for each of the power generation regions (2a) to (2d) in a later step, the second electrode film (5) is located on the left side. The first electrode films (3a) to (2a) exposed from the semiconductor film (4) are located on the second electrode film portions where the power generation regions (2a) to (2c) exist.
Extensions (3be) to (5de) extending toward one of the long sides of the long side of the substrate (1) to be combined with the extensions (3ae) to (3ce) of (3c) and an island serving as an output terminal It has an extension (5ae) extending to the region (3t). The second electrode film (5) is made of the above-mentioned TCO so that the second electrode film is used as a light receiving surface. In consideration of thermal damage to the underlying semiconductor film (4), about 20
The above-mentioned pattern is formed using a metal mask by an electron beam evaporation method or a sputter method in a heating state of about 0 to 300 ° C. As described above, the TCO usually needs to maintain the substrate (1) at a minimum of about 200 ° C. in order to obtain light transmission. Therefore, in such a process, a fine pattern cannot be obtained by using a metal mask to keep the substrate (1) in a heated state, and as a result, the second electrode film (5) is formed in each of the power generation regions (2a) to (2).
(2d) Not divided for each.

In the fourth view of a step, the power generation region (2a) SiO ₂ to protect the light-receiving surface of _{~ (2d), Si 3 N} 4, SnO 5, Ta 2 O 5 or the like inorganic translucent protective film of ( 6a) to (6d), without heating the substrate (1), using electron beam evaporation, resistance heating evaporation, CVD
It is formed by a method. It should be noted in such a process that the transparent protective films (6a) to (6d) having desired shapes are selectively obtained by a masking method using a metal mask.
That is, the light-transmitting protective films (6a) to (6d) do not heat the substrate (1), and therefore have a temperature much lower than that at the time of forming the semiconductor film (4) or the second electrode film (5) of TCO. Therefore, even if a metal mask is used, thermal deformation due to thermal expansion of the metal mask can be avoided, so that the adjacent space portions (ab) (b
c) (cd) can be favorably masked with the metal mask, and a pattern with less exudation (bleeding) of the film can be obtained. As a result of the formation of the light-transmitting protective films (6a) to (6d), the adjacent space portions (ab), (bc), and (c) of the second electrode film (5) were formed.
d), an extension (3de) of the first electrode film (3d) for the output terminal
The island region (3t) including the extension (5ae) of the second electrode film (5a) is exposed.

In the final step of FIG. 5, the light-transmissive protective films (6a) to (6d) provided for
Dry etching is performed on the O second electrode film (5) and the semiconductor film (4) using a gas having an etching action, for example, CF ₄ gas. As a result of this dry etching,
The second electrode film portion exposed from the translucent protective films (6a) to (6d), that is, the adjacent interval portions (ab), (bc), and (cd) and the extension portion (5ae) of the left end second electrode film (5a). Is removed by etching, and then the semiconductor film portion exposed by removing the second electrode film portion is removed. In this embodiment, as is apparent from FIG. 5 (B) showing a cross section of the dry etching, the removal of the semiconductor film portion is performed from the exposed surface side to the middle in the direction of the substrate (1). In order to further reduce the leakage current, etching may be performed until the current reaches the substrate.

The second electrode film (5a) thus etched is formed.
(5d) is divided for each of the power generation areas (2a) to (2d), and the first electrode films (3a) (3b) (3c) and the second electrode films (5b) (5c) (5d) Each extension (3ae) (5be) (3b
e) As a result of the superposition of (5ce), (3ce) and (5de), the photoelectric conversion outputs of the power generation areas (2a) to (2d) are output terminals (3t) (3d
It is output in a state electrically added from e).

In dry etching in the final step, the surfaces of the light-transmitting protective films (6a) to (6d) acting as a mask are:
Since the surface is exposed to the plasma, the surface is slightly roughened. On the contrary, since the protective films (6a) to (6d) constitute the light receiving surface, the straight incident light is introduced into the semiconductor film (4) as scattered light. As a result, a so-called dextiair effect can be expected by confining such incident light in the semiconductor film (4).

(G) Effect of the Invention As is clear from the above description, the production method of the present invention is the second method.
At the time of etching for dividing the electrode film into each power generation region, the protective film serving as a mask is formed by a masking method in a low temperature state. The exposed second electrode can be surely removed, so that not only a short circuit between the second electrode films and an increase in an ineffective region that does not contribute to photoelectric conversion, but also a large increase in manufacturing cost without incurring a significant increase in manufacturing cost. A power device can be manufactured.

Further, when etching the adjacent space portion of the second electrode film,
Since unnecessary semiconductor film portions can be removed, leakage current can be reduced, and the surface of the protective film can be slightly roughened by using dry etching. Then, an increase in photoelectric conversion efficiency due to light confinement can be further expected.

[Brief description of the drawings]

FIGS. 1 to 3, FIGS. 4 (A) and 5 (A) are top views for explaining the manufacturing method of the present invention for each step, and FIGS. 4 (B) and 4 (C) are FIG. 5A is a sectional view taken along line BB ′ and CC ′, and FIGS. 5B and 5C are sectional views taken along line BB ′ in FIG. FIGS. 6 and 7 are cross-sectional views taken along the line CC ', FIGS. 6 and 7 are top views for explaining the conventional manufacturing method for each process, FIGS. 8 (A) and 8 (B).
2 are enlarged cross-sectional views of one adjacent space portion for explaining a conventional defect. (1) ... substrate, (2a) to (2d) ... power generation area, (3)
(3a) to (3d): First electrode film, (4) (4a) to (4d)
... semiconductor film, (5) (5a) to (5d) ... second electrode film,
(6a) to (6d): Transparent protective film.

 ────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-62-188285 (JP, A) JP-A-59-172274 (JP, A) JP-A-55-107276 (JP, A)

Claims (4)

(57) [Claims] A first electrode film having an extended portion extending from the power generation region toward the periphery of the substrate for each of a plurality of power generation regions on the insulating surface of the substrate; Except for the portion, on the first electrode film of the power generation region and the first electrode film
The semiconductor device includes a semiconductor film including a photoactive layer on an insulating surface at an interval between adjacent electrode films, and includes an extension portion extending over the first electrode film extension portion of an adjacent power generation region exposed from the semiconductor film. The second electrode is laminated on the semiconductor film including the adjacent space, and further covers at least the second electrode film for each power generation region and an extended portion thereof, and the second electrode film is located at the adjacent space.
After selectively forming a protective film for exposing the electrode film portion by using a masking method at a temperature lower than the film forming temperature of the semiconductor film and the second electrode film, the protective film is exposed to the adjacent space using the protective film as a mask. Etching the second electrode film portion,
A method for manufacturing a photovoltaic device, wherein the second electrode film is divided for each power generation region. 2. Etching of the second electrode film portion in the adjacent space portion using the protective film as a mask is performed by removing the semiconductor film portion exposed by removing the second electrode film portion from the exposed surface side toward the substrate. The method for manufacturing a photovoltaic device according to claim 1, further comprising a step of removing at least a part of the photovoltaic device. 3. The method for manufacturing a photovoltaic device according to claim 1, wherein the etching using the protective film as a mask is dry etching. 4. The method for manufacturing a photovoltaic device according to claim 1, wherein the protective film and the second electrode film are translucent, and light is applied from the protective film.