JPH0620152B2 - Photoelectric conversion device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a photoelectric conversion element provided with a non-single crystal semiconductor containing an amorphous semiconductor having at least one PIN or PN junction on a substrate having an insulating surface ( The present invention relates to a structure of a connecting portion of a photoelectric conversion device that generates a high voltage by electrically connecting a plurality of elements (also simply referred to as elements) in series.

[Conventional technology]

2. Description of the Related Art Conventionally, an integrated photoelectric conversion device using a laser beam, that is, a laser scribing method has been known.

FIG. 1 shows a typical example of the structure of a conventional photoelectric conversion device. As shown in FIG. 1, adjacent photoelectric conversion elements (31) and (1
In the connecting part with 1), the exposed part (66) of the transparent conductive film (37)
Required a width of 20 to 60 μm as the contact area. Note that the photoelectric conversion element refers to the minimum unit of the photoelectric conversion device, and the integrated photoelectric conversion device is configured by integrating a plurality of this photoelectric conversion element.

In the conventional structure shown in FIG. 1, an open groove (13) provided in a first conductive film (consisting of (37) and (39)) by a first laser scribe, and a semiconductor layer (3). When the second open groove (18) formed in () overlaps, the right end of the second open groove (18) is on the right side of the drawing from the left end (14) of the first open groove (13). It is known that the distance (65) between them becomes negative.

In such a structure, when the second open groove (18) is formed by laser scribing, the semiconductor in the shaded area (69) (generally composed of an amorphous semiconductor) is a polycrystal having conductivity due to the energy of laser light. Will be.

As a result, the first electrode (37) of the first element (31), the second electrode (38) of the second element (11), and the second electrode (38) of the second element (11). The electrode (38) and the first electrode (39) of the second element are short-circuited. In addition, the fluctuation of scanning by the laser scribing required for manufacturing the second open groove is ±
20 μm Since it is generally ± 10 μm, the contact with the second electrode must be exposed as much as 20 to 60 μm as shown in (66). In this case, the first element (31) of the first element (31) must be exposed. There was a problem that the output adjustment of the laser beam for intentionally leaving the upper end surface (66) of the electrode (37) was extremely delicate.

As a result, the manufacturing method for realizing the structure shown in FIG. 1 was industrially completely impractical.

[Problems to be Solved by the Invention]

The present invention relates to the problem of leak current between photoelectric elements due to the structure of the conventional photoelectric conversion device described above, the problem of short circuit between the first electrode and the second electrode of the photoelectric conversion element, and further to the structure. It is an object of the present invention to solve the problem of difficulty in manufacturing due to that and obtain a highly reliable photoelectric conversion device.

[Means for Solving the Problems]

The present invention provides a first electrode provided on a substrate having an insulating surface, an amorphous semiconductor provided on the electrode,
A photoelectric conversion device in which a plurality of photoelectric conversion elements each having a second electrode provided on the semiconductor are connected in series, wherein the first electrode has two open electrodes at a connection portion between adjacent photoelectric conversion elements. A conductive material that forms a first electrode is formed in a convex shape between the two open grooves, and is separated by the groove. In one of the open grooves, the first conductive material of one photoelectric conversion element is formed. The photoelectric conversion device is characterized in that the side surface and the upper end portion of the electrode are connected to the second electrode of the other photoelectric conversion element through an opening formed in the amorphous semiconductor by laser light. .

According to the present invention, a non-single-crystal semiconductor having at least a PN or PIN junction and a non-single-crystal semiconductor provided under the second open groove for electrically connecting the first and second photoelectric conversion elements are formed. It is obtained by simultaneously removing and forming the first electrode by laser scribing.

By the laser scribing, the second electrode of the second element is connected to the exposed side surface of the first electrode of the first element and the contact of the upper end portion (also referred to as the upper end surface or the flat end portion) of the first electrode. The photoelectric conversion elements can be connected and connected in series.

The upper end of the first electrode is exposed due to the difference in the degree of scribing (heat resistance and scattering) between the non-single-crystal semiconductor and the translucent conductive film during laser scribing.

This is because when the transparent conductive film forming the first electrode and the non-single-crystal semiconductor on the transparent conductive film are simultaneously laser scribed to form an open groove, the open groove is formed in two steps. That is, the width of the opening formed in the transparent conductive film below is smaller than the width of the opening formed in the non-single crystal semiconductor, and as a result, the width of the opening is larger than the thickness of the transparent conductive film. This is based on the experimental fact that a flat portion having a width of is formed on the upper end of the transparent conductive film.

By using the laser scribing method described above, the upper end of the transparent conductive film can be exposed in the open groove in a self-aligned manner (redundant).
It is something that can be given a degree.

The first electrode (lower side) between adjacent photoelectric conversion elements
And the second electrode (upper electrode) of the other element are electrically connected to the first electrode by a lead (coupling portion) extending from the second electrode at a contact including the side surface and the upper end surface thereof. Thus, the position of the open groove of the scribe line can be provided with redundancy.

Further, by providing the second groove so as to enter the inside of the first electrode of the first element rather than the first groove forming the first electrode, the first and second grooves are formed. Between the first
A part of the electrode material of (1) has a convex portion and is left. The convex portion has a function of preventing the semiconductor having an insulating property filled in the first open groove from being polycrystallized by laser scribing.

Due to this convex portion, the electrical isolation between the first electrodes of the first element and the second element and the electrical short circuit between the first and second electrodes of the second element (conductivity is (Due to the polycrystal produced by laser annealing).

Further, the second electrode of the second element is extended by making the side surface and the upper end of the translucent conductive film forming the first electrode of the first element closer to the contact and extending the second electrode of the second element. It is possible to increase the surface area (contact area) required for the contact, and simultaneously to obtain a contact resistance of 1 Ω / cm (1 Ω per 1 cm width) or less.

Further, by providing the second groove on the position of the first electrode of the first element, the first photoelectric conversion element of the first photoelectric conversion element caused by the fluctuation (having ± 20 μm) at the time of scanning of the laser scribe is provided. Therefore, it is possible to realize a structure that prevents a short circuit between the second electrode and the first electrode of the second photoelectric conversion element.

Details of embodiments of the present invention will be described below with reference to the drawings.

〔Example〕

FIG. 2 is a vertical sectional view showing a manufacturing process of the photoelectric conversion device according to the embodiment of the present invention.

In FIG. 2A, a substrate having an insulating surface, for example, a transparent substrate (1) (in this embodiment, a glass plate (for example, a thickness) is used.
IT is used as a transparent conductive film (2) over the entire upper surface of 1.2 mm, 60 cm in length (left and right in the drawing) and 20 cm in width).
O (about 1500 Å) + SnO ₂ (200 to 400 Å) or a transparent conductive film (1500 to 2000 Å) mainly composed of tin oxide to which a halogen element is added is vacuum deposited, LP CVD, plasma
It was formed by the CVD method or the spray method.

After this, from the lower side or the upper side of this substrate (1), output a laser beam with a YAG laser processing machine (made by Nippon Laser) 0.5 to 2
In addition with W power, a first open groove (13) was formed.

At the time of forming the first open groove, the spot diameter of the laser beam was 30 to 70 μmφ, typically 50 μmφ, and irradiation was performed under the control of a microcomputer.

Due to the first open groove (13), each element region ((5), (3
A first electrode (2) was produced on (1) and (11)).

The groove (13) formed by laser scribing has a width of about 50μ.
The length was 20 m and the length was 20 cm, and each of the first electrodes was completely cut and separated.

Further, the upper surface was immersed in a gas or liquid containing a halogen element to remove the lower oxide. CF Br, CFHF, and SiF were used as the gas containing the halogen element, and plasma etching was performed using electromagnetic energy.

When a liquid was used, the lower oxide was etched by immersing it in a 1/10 HF (40% HF diluted 10 times with water) solution for 30 seconds to 1 minute.

Thus, the width of the first element (31) and the second element (11) was set to 10 to 20 mm. The open groove between them was 20 to 70 μm, for example 50 μm, and each was completely isolated.

By the laser scribing method described above, an open groove (for example, (1) is used to cut and separate the translucent conductive film (2) forming the first electrode.
3)) was formed.

After this, plasma CVD, photo CVD or LP C
A non-single crystal semiconductor layer (3) having a PN or PIN junction was formed by VD method to a thickness of 0.2 to 1.0 μm, typically 0.4 to 0.5 μm. A typical example is a P-type semiconductor (Si _x C _1-x
x = 0.8 50 to 150 Å) -I type amorphous or semi-amorphous silicon semiconductor (0.4 to 0.5 μm) -N-type single crystal consisting of semiconductor having N type microcrystal (100 to 200 Å) Semiconductor or P-type semiconductor (Si _x C _1-x ) -I type, N type, P type Si semiconductor-I type Si _x Ge
_1-x ) semiconductor _- tandem type PINPIN ... PIN junction with two PIN junctions and one PN junction consisting of N-type Si or Si _x C1 _-x ) (0 <x <1) semiconductors It is a semiconductor.

The non-single crystal semiconductor (3) was formed with a uniform film thickness over the entire surface of the first trench and the element region. Further, as shown in FIG. 2B, a second laser groove is used to form a second open groove (18) on the left side of the first open groove (13).
A distance of 50 to 300 μm in a width of 50 μm from the first open groove (13), that is, a distance of 50 to 300 μm from the first open groove (13) inside the first photoelectric conversion element (31). Formed by letting in.

The second groove (18) exposes the side surfaces (8), (9) and the upper end surface (6) of the first electrode. At the same time, a part of the translucent conductive film was left as a convex part (16) between the second open groove (13) and the second open groove (13).

When forming the second groove (18), the first electrode
Regarding exposing the upper end surface (6) of (2), the third
This will be described with reference to the drawings and FIG.

FIG. 3 is an enlarged view of a portion of the second open groove (18) shown in FIG. 2, and FIG. 4 is a laser beam irradiation condition (scanning speed) and a transparent conductive film as a first electrode. It shows the relationship with the width of the flat part formed on the upper end surface of the.

In FIG. 3 (A), the second open groove (18) is provided in addition to the side surfaces (8) and (9) of the transparent conductive film (2), and the flat end surface (upper end portion) (6).
Exists and configures the contact.

FIG. 3 (B) is a scanning electron micrograph (SEM photograph) (magnification 4) showing a top view of the flat end portion (6) in FIG. 3 (C).
000 times, acceleration voltage 10KV). In FIGS. 3 (B) and 3 (C), (70) is a crack generated in the substrate glass (1), (71) is a residue left around the open groove caused by laser scribing, and (6) is a flat conductive film. It is a department.

This flat end portion is formed by self-alignment because the translucent conductive film is 4 times stronger than the laser light and is less likely to be scribed as compared with the non-single crystal silicon semiconductor.

It is possible to utilize this characteristic not only on the side surface but also on the upper end portion (6).
This is also the reason why the second groove can be formed at the same time.

By using the flat portion (6) as a contact, the substantial contact resistance at the connecting portion could be reduced from 1.5 Ω / cm in the case of only the side surface to 0.3 to 1 Ω / cm.

FIG. 4 shows the width of the upper end portion shown by (6) in FIG. 3 (A) when the laser scribing for forming the second open groove and the scanning at the time of the laser scribing are performed. It shows the relationship with speed.

The laser scribe conditions are frequency 30KHz, output 1.
1W, light diameter 50μm, laser light scanning speed is 60cm / min.
It is 240 cm / min.

When the scanning speed was variable and the speed was 60 cm / min or more, the width of the flat portion could be made more than the thickness of the coating. That is, by increasing the scanning speed, the width can be increased, and the contact area can be increased accordingly, so that the contact resistance can be reduced.

Incidentally, FIG. 3 (C) shows the case where the scanning speed in FIG. 4 is 120 cm / min.

However, if the width of the flat portion (6) is 5 μm or more, the width becomes too wide for integration, and the effective area is reduced, which is rather inconvenient.

As described above, when a laser beam is applied to the upper surface of a work piece in which the transparent conductive film (2) and the semiconductor (3) both cover the substrate, the laser beam output and the scanning speed are increased. Accordingly, the flat part (6) having a width equal to or larger than the film thickness of the translucent conductive film (2) could be formed.

Further, as is clear from the SEM photograph of FIG. 3 (C), this flat portion is simultaneously subjected to laser scribing of the semiconductor and the transparent conductive film thereunder at the same time, that is, in a self-aligning manner. Because it is made, the fluctuation of its width is ± 0.
It could be suppressed to 5 μm.

Further, in FIG. 3 (A), a first open groove (13) is provided in the translucent conductive film (2) on the substrate (1), and a second open groove is formed from the left end portion (14). The right end (9) of (18) is located on the left side, and the distance (15) between them is positive.
50 μm). As a result, the convex portion composed of the same material as the first electrode (37) (thickness 0.2 μm) of the first element
(16) remains.

The presence of this convex portion is important. That is, when forming the second open groove 18, the amorphous silicon 3 is polycrystallized in the shaded area 69 by laser annealing and becomes conductive. However, due to the presence of this convex portion, the first open groove
The amorphous semiconductor in the vicinity of the substrate filled in (13) is not polycrystallized and can have an insulating property. That is,
When this convex portion remains, the conductive polycrystalline semiconductor region is not formed in the vicinity of the interface between the semiconductor filled in the first opening and the substrate, and as a result, the second opening is formed. The first and second conductive films (39), (3 of the second element (11)
It is possible to obtain the effect that 8) are not short-circuited with each other.

After forming the above-mentioned second open groove (18), the whole is reduced to 1/10 HF.
The contact resistance was set to 1 Ω / cm or less by immersing for 30 seconds to 1 minute to remove the lower silicon oxide on the surface.

In this embodiment, the surface of the first electrode (1
4) Instead of exposing (see FIG. 1), an opening groove is formed in the first electrode by laser light, so that the laser light
There is no problem even if it is 1.5 to 5 W, which is too strong. That is, it has a usefulness in industrial application that it can give a margin to the intensity of the output pulse of the laser beam.

As described above, the second open groove forming the connecting portion between the adjacent photoelectric conversion elements was produced.

Further, in FIG. 2, the second electrode (4) on the back surface is formed as shown in FIG. 2 (C) on the upper surface, and the third electrode for cutting and separating is formed by the third laser scribing method.
The open groove (20) was provided.

This second electrode may be manufactured at the mask edge without using laser light.

This second electrode (4) is formed of a transparent conductive film with a thickness of 500 to 1400Å by ITO (indium tin oxide),
Further, silver as a reflective metal is formed on the upper surface thereof to a thickness of 300 to 3000 Å, and a two-layer film of aluminum, copper, nickel or chromium is further formed on the upper surface thereof.
In this example, ITO is 1050Å, silver is 1000Å, and copper is 15Å.
It has a three-layer structure of 00Å.

This ITO and silver promote the reflection of incident light (10) on the back side,
It is for effectively photoelectrically converting long wavelength light of 600 to 800 nm.

Furthermore, this ITO is connected to the first photoelectric conversion element (3
Direct contact with the contacts (6), (8) with the first electrode (37) in 1). That is, the oxide conductive film (37) of the transparent conductive film and the other oxide conductive film (38) are in close contact with each other to form a contact on the side surface and the upper end portion. Therefore, no oxide insulator is formed at this contact portion, which is extremely preferable in terms of reliability.

These were formed by electron beam evaporation or plasma CVD at a temperature of 300 ° C or less, which does not deteriorate the semiconductor layer.

Further, it is effective to form titanium to a thickness of 10 to 30 Å under silver to improve the adhesion between silver and ITO.

This ITO is also useful for preventing a decrease in reliability due to a chemical reaction between the semiconductor (3) and the back electrode (4), that is, improving reliability.

The back electrode (second electrode) like this is irradiated with laser light from above to cut and separate the second electrode or transform it into an oxide insulator to form the third open groove (20) (width 50 μm). Formed.

This laser light slightly scoops out an N- or P-type semiconductor layer which is in close contact with the semiconductor, especially the upper surface, like (40), and between the adjacent first element (31) and second element (11). The configuration was such that crosstalk (leakage current) due to residual metal or a conductive semiconductor in the groove was prevented.

Of course, a screen printing method may be used to form the groove of the second electrode.

Thus, as shown in FIG. 2 (C), a plurality of elements (3
It was possible to make a photoelectric conversion device in which 1, (11) were connected in series at the connecting part (12).

FIG. 2 (D) shows that the present invention has been completed as a photoelectric conversion device, that is, a silicon nitride film (21) of 5000 to 2000 is formed as a passivation film by a plasma vapor phase method.
It is formed with a thickness of Å to prevent the generation of leakage current between each element.

Further, external lead terminals were provided in the peripheral portion, and these were filled with an organic resin (22) such as polyimide, polyamide, Kapton or epoxy.

Thus, with respect to the irradiation light (10), each element on the substrate (60 cm x 20 cm) as in this example has a width of 14.350 mm, a width of the connecting portion of 150 μm, a width of the external extraction electrode portion of 10 mm, and a peripheral portion of 4 mm, the effective area (192 mm × 18.35 mm × 32 steps 1106 cm ²
92.2%) was obtained. As a result, when the segment (each photoelectric conversion element) has a conversion efficiency of 10.3%,
The panel achieved a conversion efficiency of 9.95% (AM1 (100 mW / cm ² )), and it was possible to have an output power of 10.4 W as a photoelectric conversion device.

In addition, this panel is also 40 cm × 20 cm, 60 cm × 20 cm
Alternatively, 40 cm × 120 cm 6 pieces, 4 pieces or 1 piece can be combined in series in an aluminum sash or a carbon fiber frame to be packaged, and a 120 cm × 40 cm NEDO standard high power panel can be provided.

In addition, this NEDO standard panel is laminated with another glass plate by the Seaflex on the reflection surface side (upper side in the drawing) of the photoelectric conversion device of the present invention to form a laminated glass, and the photoelectric conversion device is arranged between them, wind pressure, rain It is also effective to increase the mechanical strength against such problems.

In FIGS. 2 to 4, light is incident on the lower glass plate. However, in the present invention, the incident side of the light is irradiated from the upper side, the upper electrode is made of transparent ITO, and the substrate is a flexible plastic insulating substrate or an insulating film on a metal (alumina film is formed on aluminum). It is likewise possible to use a substrate provided with a substrate.

Above is the spot diameter of YAG laser 0.5 ~ 3W
(30 μm) (1 to 5 W (50 μm), but by further reducing the spot diameter in the technical idea, this connecting portion is made smaller, and the effective area as a photoelectric conversion device is further improved. It goes without saying that you can do it.

〔The invention's effect〕

As is apparent from the above examples, by using the present invention, it is possible to provide the connecting portion for connecting adjacent photoelectric conversion elements with high reliability.

In particular, in the connecting portion, the material of the first conductive film is left in a convex shape between the first open groove and the second open groove, and the material is left between the photoelectric conversion elements or between the first and second electrodes. I was able to secure the isolation.

Further, the second electrode of the second element is extended by being brought into close contact with the contact formed by the side surface and the upper end portion of the translucent conductive film forming the first electrode of the first element,
It was possible to increase the surface area (contact area) required for contact at the connecting portion and substantially reduce the contact resistance.

Furthermore, since the contact area at the connecting portion between photoelectric conversion elements could be substantially increased, the required area of the connecting portion (contact portion) (projected area viewed from above or below) was compared with that in the conventional method. I was able to reduce it. As a result, it was possible to help improve the effective area of the panel.

[Brief description of drawings]

FIG. 1 shows an outline of a connecting portion of a conventional photoelectric conversion device. FIG. 2 is a vertical sectional view showing a manufacturing process of the photoelectric conversion device of the example. FIG. 3 is an enlarged view of the second groove portion of the embodiment. FIG. 4 shows the relationship between the width of the flat end and the scanning speed of laser light.

Claims (1)

[Claims] 1. A first device provided on a substrate having an insulating surface.
A photoelectric conversion device in which a plurality of photoelectric conversion elements each having an electrode, an amorphous semiconductor provided on the electrode, and a second electrode provided on the semiconductor are connected in series, and adjacent photoelectric conversion elements are provided. In the connecting portion between the first electrodes, the first electrodes are separated from each other by two open grooves, and a conductive material that forms the first electrodes in a convex shape is formed between the two open grooves. In one of the grooves, the side surface and the upper end of the first electrode of the one photoelectric conversion element are connected to the second electrode of the other photoelectric conversion element through the groove formed in the amorphous semiconductor by laser light. A photoelectric conversion device characterized in that