JPH0518275B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a photoelectric conversion device using a laser processing method using a non-single crystal semiconductor.

This invention further includes a second conductive film made of a conductive oxide on a non-single crystal semiconductor on a substrate and a metal conductive film containing Al, Ag, Cu, Mg, Ti or Cr as a main component on the conductive oxide, and A laminated film with an insulating film is formed on the film, and this laminated film is irradiated with laser light.
Forming grooves with approximately the same shape in the second conductive film and the insulating film by selectively removing the laminated film without damaging the semiconductor or without damaging, oxidizing, or insulating the semiconductor to a depth of 1000 Å or less (hereinafter referred to as laser scribing or LS).

This invention electrically connects in series a plurality of photoelectric conversion elements (also simply referred to as elements) in which non-single-crystal semiconductors including amorphous semiconductors having at least one PN or PIN junction are provided on an insulating substrate. The present invention relates to the structure of a second electrode in a photoelectric conversion device that generates voltage.

The arrangement, size, and shape of elements in the device of the present invention are determined by design specifications. However, in order to simplify the content of the present invention, in the following detailed description, the first electrode on the lower side (substrate side) of the first element and the second electrode on the right side of the first electrode will be described. 2
This description is based on the case where the electrodes (on the semiconductor, that is, on the side away from the substrate) are electrically connected in series.

In such a configuration, the third groove for separating the second electrodes of the first element and the second element from each other is formed of indium oxide or tin oxide in close contact with the N or P type non-single crystal semiconductor layer. The present invention is characterized in that a conductive film (hereinafter referred to as CO) containing CO as a main component is provided, and a laminated film is formed by laminating a conductive metal and an insulating film on the conductive film.

Further, the present invention provides that after this step, an organic resin molding material is formed on the upper surface of the entire area except the electrode part (pad area), and the insulating film in the pad area is removed using the organic resin molding material as a mask. In addition to improving moisture resistance, the insulating film exists only under the organic resin molding material, making it possible to form an insulating film for laser scribing while still allowing good connection between the electrode (pad) and the outside. This is what I did.

According to the present invention, a second electrode conductive film provided on a semiconductor is scribed using a laser beam to form separate electrodes from each other. At that time, in order to prevent the underlying semiconductor, especially the hydrogenated amorphous semiconductor, from becoming polycrystallized and becoming conductive when exposed to high-temperature laser light irradiation of 1800°C, a single or multilayer conductive layer is placed on the CO. In this method, an insulating film is laminated on a conductive metal and an insulating film on this metal, and the LS is used to form a compound with the semiconductor under the third trench, and to prevent polycrystallization of this semiconductor due to laser annealing.

In addition, these conductive metals include Al, Ag, Cu,
It is characterized by using Mg, Ti, and Cr, and the sheet resistance of this back electrode (second electrode) is 0.5Ω/□ or less.

In the present invention, the back electrode as a photoelectric conversion device is
Reflecting the incident light on this back surface was effective in improving the conversion efficiency.

For this reason, it is close to CO and has a high reflectance of 1000 ~
Two-layer structure made of aluminum with a thickness of 2000 Å or titanium with a thickness of 0 to 50 Å and a layer of 100 to 100 Å on the top surface.
500 Å thick silver and further 500 to 5000 on its top surface
It has a four-layer structure by laminating aluminum with a thickness of 1.5 Å.

Such a two-layer or four-layer structure can increase the reflection of light on the back surface and can be useful for improving conversion efficiency. Furthermore, the electrical conductivity and sheet resistance are
In addition to improving the resistance to 0.5Ω/□ or less, the metal itself is soft, so it has the advantage of not applying strain stress to the semiconductor. However, when it comes to maskless laser processing, which is extremely important, in the case of a laminated film made only of CO and conductive metal, an open groove is formed by selectively removing only the conductive film or only the conductive film and the semiconductor below it. It was extremely difficult to do so, and it was not suitable for industrial use. Taking these features into consideration, the present invention creates a laminate in which an insulator is formed on this conductor in order to implement maskless laser processing with a margin for mass production. This prevents the heat from dissipating to the outside. That is, an insulating film such as silicon nitride, silicon carbide, or silicon oxide (SiO, SiO ₂ ) was formed on this conductive film to a thickness of 300 to 5000 Å. In particular, SiO, which has a sublimation property with respect to laser light, is preferable because it can be produced by the same electron beam evaporation method as the CO and metal formed below.

The present invention uses conductive film metal such as Al to further improve the operation speed of LS as a conductive metal.
Chromium 100 as +Cr or Ti+Ag+Al+Cr
It is interposed between the conductive metal and the insulating film to a thickness of ~3000 Å, preferably 300 to 1000 Å, to reduce reflection of laser light and efficiently raise the temperature of the conductor.

CO prevents deterioration due to reactions between semiconductors and conductive metals during long-term use, promotes reflection of incident light, and has sublimation properties. However, because CO is transparent, it absorbs only a small amount of laser light. Also, conductive metals such as Al have high electrical conductivity, and the sheet resistance
We were able to create a resistance of 0.5Ω/□ or less. It also has excellent reflection of incident light from the substrate side. However, it is not sublimable, and the thermal conductivity of the absorbed energy of the laser beam in the outward direction of the plane is large, which tends to hinder the temperature rise in the LS section.

In addition, the reflectance of the irradiated laser beam is high.

An insulating film such as SiO is an anti-reflection film for the irradiated laser beam, and can prevent thermal energy for raising the temperature of the conductive film from being dissipated to the outside (outward direction). Furthermore, when sandwiching chromium, the reflectance is much lower than that of Al and Ag, and together with the insulating film, it is possible to efficiently absorb the thermal energy of the laser beam.

As described above, the structure of CO-conductive metal-insulator as the back electrode of the photoelectric conversion device of the present invention is an extremely effective laminated film structure since it has the respective functions.

Therefore, by combining these films,
The non-single crystal semiconductor under the groove irradiated with the LS laser light is not polycrystallized by heat, and the conversion efficiency is improved while selectively removing CO in the groove and the metal above it. Multiple electrodes could be fabricated without using a mask.

In addition, moisture resistance can be improved by forming an organic resin molding material on the top surface of the entire area except the pad area.In addition, by removing the insulating film in the pad area using the organic resin molding material as a mask, the pad and external I was able to make a good connection with.

The details of the invention are shown below with reference to the drawings.

FIG. 1 is a longitudinal sectional view showing the manufacturing process of the present invention.

In the drawings, a transparent substrate 1 having an insulating surface, such as a glass plate, an organic resin, or a flexible substrate coated with a silicon nitride film on an organic resin (for example,
1.2mm, length [left/right direction in the drawing] 60cm, width 20cm]
was used. Furthermore, a light-transmitting conductive film such as ITO (indium oxide/tin oxide mixture, i.e., tin oxide mixed with indium oxide at 10%
(approximately 1500 Å) + SnO ₂ (200 to 500
Å) or a transparent conductive film whose main component is tin oxide doped with halogen elements such as fluorine (1500~
20000Å) by vacuum evaporation method, LPCVD method, plasma
It was formed by CVD method or spray method.

After this, YAG laser processing machine (manufactured by Nippon Laser)
Output of 0.3~ by using a wavelength of 1.06μ or 0.58μ) or a nitrogen laser processing machine (manufactured by Nippon Laser, wavelength of 337nm)
Add 3W (focal length 45mm) and spot diameter 20~
70μφ, typically 50μφ, was controlled by a microcomputer. Furthermore, this irradiation laser beam was scanned to form a first groove 13 which is a scribe line, and a first electrode 2 was produced in each inter-element region 31, 11.

The first open groove 1 formed by this first LS
In No. 3, each electrode of the first CTF was completely cut and electrically isolated by approximately 50 μm in width and 20 cm in length.

Thereafter, a non-single crystal semiconductor layer 3 of 0.2 to 0.8 μm, which generates photovoltaic force by light irradiation, is formed on the upper surface of the electrode 2 and the groove 13 by plasma CVD, LPCVD, photoCVD, or a combination thereof.
Typically, it was formed to a thickness of 0.7μ.

A typical example is a P-type semiconductor (SixC _1-x x=0.8 approx.
100 Å) - I-type amorphous or semi-amorphous silicon semiconductor (approximately 0.7 μ) - N-type microcrystalline (approximately 500 Å) silicon semiconductor;
SixC _1-x x=0.9 about 50Å is stacked to form one PIN
Non-single crystal semiconductor with junction or P-type semiconductor (SixC _1-x ) - I type, N type, P type Si semiconductor - I type
SixGe _1-x semiconductor - two types of N-type Si semiconductor
Tandem type with PIN junction and one PN junction
PINPIN...This is a semiconductor 3 of PIN junction.

The substrate and the back surface of the semiconductor were formed to have a textured structure so that the non-single crystal semiconductor 3 had a uniform thickness over the entire surface or total reflection occurred on the back surface.

Furthermore, as shown in FIG.
The open groove 18 was formed by the second LS process.

In this drawing, the first and second open grooves 13, 18
The centers of the two are shifted by 100μ.

The second open groove 18 thus exposed the side surfaces 8, 9 of the first electrode. Furthermore, the upper end portion 7 of the first electrode with a width of 0 to 5 μm could also be fabricated by the operating speed of the LS.

In FIG. 1, as shown in FIG. 1C, a back laminated film 4 and a connector 30 are formed on this top surface, and a third groove for cutting and separation at the third LS is formed. No. 20 was manufactured by making the second conductive film and the insulating film thereon substantially the same shape.

This second electrode 4 is formed by forming a conductive oxide film (CO) 45, 45', which is a feature of the present invention, in close contact with a P or N type semiconductor. Its thickness is 100 ~
It was formed to a thickness of 3000 Å.

As this CO, ITO (a mixture whose main components are indium oxide and tin oxide) 45, 45' was formed in close contact with the N-type semiconductor layer. As this CO, it is also possible to form tin oxide as a main component in close contact with indium oxide or a P-type semiconductor layer.

These were formed using electron beam evaporation or PCVD at a temperature of 300°C or lower to avoid deteriorating the semiconductor layer.

The following metals 46 and 46' on CO45 were investigated using a similar electron beam evaporation method.

Al, Ag, CuMg, Ti, and Cr were fabricated. They are (1) Al (1000 to 5000 Å), (2) Al (1000 to 5000 Å) - Cr (100 to 3000 Å), (3) Ti (0 to 50 Å) - Ag (100 to 1000 Å) - Al (1000 Å)
~5000Å) (4) Ti(0~50Å)−Ag(100~1000Å)−Al(1000Å)
~5000Å)-Cr(100~3000Å). Mg or Ag, which also has a high reflectance, may be used instead of Al. Also
It is effective to use Cu in place of Al in order to promote reflection of long wavelength light of 0.7 to 2μ. For general sunlight and fluorescent light, methods (1) and (2) above were practical because they could be made at low cost.

Further, on this upper surface, an insulating film 47, which is a feature of the present invention, is formed using silicon oxide (SiO or SiO ₂ ), silicon nitride (Si ₃ N ₄ ), or Si ₃ N _4-x (0<x<4), silicon carbide ( SiC _1-x (0<x<1)) was deposited by electron beam evaporation or plasma vapor deposition.

By adopting such a laminated film structure, in the LS of the present invention, damage or oxidation insulation 34 is caused only to a depth of 1000 Å or less (generally 200 Å or less), and the first element region 31 is covered. I was able to form it.

The reason why the conductive film and the insulating film can have approximately the same shape in the groove formed by the LS of the present invention is considered as follows. In other words, by forming a multilayer film of sublimable CO, aluminum or Al-Cr on its upper surface, and an insulating film, each component interacts with the other during laser light irradiation, and the temperature of CO becomes higher than the sublimation temperature. This heat is sufficiently stored in the conductive film and is vaporized and scattered as if bursting. As a result, this vaporization removes vaporization heat, so that the non-single crystal semiconductor containing amorphous silicon underneath is not polycrystallized or removed, and the present invention is used as the target electrode for laser irradiation. It has been experimentally determined that laminated films are ideal.

As a result of this step, the third electrical separation between the second electrodes 39 and 38 where the open circuit voltage of the first element occurs
The open groove 20 is cut with a laser beam (typically 20 to 100μφ
50μΦ) was formed.

The case where the laminated film 4 is cut and separated by irradiating the third LS laser beam from above to form the open grooves 20 is shown.

In this way, as shown in FIG. 1C, a photoelectric conversion device in which a plurality of elements 31, 11 are directly connected by the connecting portion 12 was able to be manufactured.

FIG. 1D shows the present invention being further completed as a photoelectric conversion device, that is, a silicon nitride film 2 is made by a plasma vapor phase method as a passivation film.
1 was uniformly formed to a thickness of 500 to 2000 Å to further prevent leakage current between each element due to adsorption of moisture, etc.

Furthermore, an external lead-out terminal was provided at the peripheral portion 5.

These were filled with an organic resin 22 such as polyimide, polyamide, Kapton or epoxy.

Thereafter, the entire structure was immersed in dilute hydrofluoric acid to dissolve away the insulating film in the pad region 5.

In this way, the photovoltaic force generated by the irradiation light 10 flows from the first electrode of the first element of the contact 30 to the second electrode of the second element, making it possible to establish a series connection.

As a result, each element on this board (60 cm x 20 cm) has a width of 14.35 mm, a width of the connecting part of 150 μm, a width of the external lead electrode part of 10 mm, and a peripheral part of 4 mm.
There are 40 stages within mm x 192 mm, and the effective area (192 mm x
14.35 mm 40 stages 1102 cm ² or 91.8%).

If the segment has a conversion efficiency of 10.5% (1.05cm), the panel will have a conversion efficiency of 7.3% (theoretically it would be 7.8%, but the effective conversion efficiency was reduced due to the resistance of the 40-stage connection) (AM1 [100mW /cm ² ]),
It was possible to have an output power of 6.1W.

Furthermore, when this panel is subjected to a high temperature storage test at 150℃, the percentage decreases to below 10% after 1000 hours, for example, 20 panels.
The worst case scenario was a decline of only 4% (X = 1.5%).

This is an astonishing value considering that when conducting a reliability test under the same conditions using the conventional mask method, as many as 17 panels were rendered inoperable in 10 hours.

FIG. 2 shows an external lead electrode portion of the photoelectric conversion device.

FIG. 2A corresponds to FIG. 1, but the external extraction electrode section 5 has a pad 49 that contacts the external extraction electrode 57, and this pad 49 is connected to the second electrode (upper electrode) 45, 46. It is connected. At this time, the pressure applied to the electrode 57 is too strong and the pad 49 penetrates the semiconductor 3 underneath, and the opening groove 13' is formed to prevent the first electrode of an adjacent element from being shot even if it comes into contact with the first electrode 2. is provided.

In addition, the outer part has an open groove 5 in which the first electrode, the semiconductor, and the second electrode are simultaneously scribed with one LS.
It is cut and separated at 0.

Furthermore, in FIG. 2B, 8' is attached to the lower first electrode 2.
Another pad 48 connected at 7' is provided connected at 18' with a second electrode material.

Further, the pad 48 is in contact with an external lead electrode 58 and is electrically connected to the outside.

Here again, the pad 48 is electrically isolated from the adjacent photoelectric conversion device by the grooves 18', 20'', and 50, and forms a side contact with the first electrode 2 at 8'.

In other words, the photoelectric conversion device is covered with the organic resin mold 22 except for the electrode portions 5 and 45, thereby improving moisture resistance. Also, using this mold 22 as a mask, the insulator on the pads 5 and 55 is etched, leaving the insulator only under a certain mold material.

Also this panel for example 40cm x 60cm or 60cm x
By combining 2, 4 or 1 piece of 20cm, 40cm x 120cm in an aluminum sash or carbon fiber frame, you can make a package of 120cm x 40cm NEDO.
It is possible to provide panels for standard high power.

In addition, it is also effective for this NEDO standard panel to increase its mechanical strength against wind pressure, rain, etc. by attaching a fluorine-based protective film using Seaflex to the reflective surface side (upper side in the drawing) of the photoelectric conversion device of the present invention. It is.

In the present invention, glass is particularly used as the substrate among light-transmitting insulating substrates.

However, it is effective to use as this substrate a composite substrate in which aluminum oxide, silicon oxide, or silicon nitride is formed on a flexible organic resin, aluminum, stainless steel, etc. to a thickness of 0.1 to 2 μm. In particular, when this composite substrate is applied to the embodiment described above, it has a so-called blocking effect that prevents silicon oxide or silicon nitride from damaging the CTF on the upper surface and creating a mixture of the substrate and CTF, which is particularly effective. It was hot.

Further, the details of the present invention will be supplemented by describing examples below.

Example 1 This embodiment is illustrated according to the drawing in FIG.

That is, as the light-transmitting substrate 1, a light-transmitting organic resin, Sumilite 1100 manufactured by Sumitomo Bakelite Co., Ltd., thickness 100μ,
Or translucent glass thickness 1.1mm, length 60cm, width 20
cm was used.

A silicon nitride film with a thickness of 0.1 μm was formed on this upper surface using the PCVD method to form a blocking layer.

Furthermore, on top of that, CTF is ITO1600Å + SnO ₂ 300Å
was fabricated by electron beam evaporation.

Furthermore, after this, the first open groove was made with a spot diameter of 50μ.
A YA laser with an output of 1 W was controlled by a microcomputer at a scanning speed of 120 cm/min.

Furthermore, the first electrode semiconductor was scanned in a rectangular manner at a position 5 mm inside the edge of the glass using a laser beam output of 1 W at the edge of the panel to prevent an electrical short circuit with the frame of the panel.

The element regions 31 and 11 were 15 mm wide.

After this, the well-known PCVD method was used to create the structure shown in Figure 2.
A non-single crystal semiconductor with one PIN junction was fabricated.

Its thickness was approximately 0.7μ.

After this, the first element 3 is removed by 100μ from the first groove.
By shifting 1, the spot diameter is 50μφ and it is 69cm/
A second open groove 18 was made as shown in FIG. 2B by LS in the air at an operating speed of 1 W and an output of 1 W.

Furthermore, ITO was coated as CO on the entire surface by electron beam evaporation to an average thickness of 1050 Å, and aluminum (2000 Å) and chromium were coated on the top surface to a thickness of 500 Å.
The second electrode 45 and the connector 30 were fabricated by electron beam evaporation to a thickness of .ANG.

Furthermore, SiO was laminated to a thickness of 1200 Å by electron beam evaporation to form a laminate.

Furthermore, connect the third open groove 20 to the third LS.
A YAG laser was used to form the conductive film and the insulating film in approximately the same shape at the open grooves using a 1 W output of 50 μΦ and an operation speed of 90 cm/min to obtain FIG. 2C.

Thereafter, a silicon nitride film with a thickness of 1000 Å was formed at a temperature of 200° C. by the PCVD method to form a passivation film 21.

Then, 40 15mm wide elements are placed on a 20cm x 60cm panel.
I was able to make steps.

AM1 (100mW/cm ² ) as the effective efficiency of the panel
We were able to obtain an output of 7.8% and an output of 6.1W.

The effective area is ^1102cm2 , 91.8% of the whole panel
was able to be used effectively.

In this embodiment, by overlapping the upper protective organic resin 22 as shown in FIG. This made mass production possible at an extremely low cost.

In FIGS. 1 and 2, light was incident from the lower translucent insulating substrate.

However, in the present invention, the light incident side is not limited to the lower side, and it is also possible to use ITO as the upper electrode and irradiate light from the upper side, and it is also possible to use a flexible substrate instead of a glass substrate. It is possible.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing the manufacturing process of the photoelectric conversion device of the present invention. FIG. 2 is a partially enlarged longitudinal sectional view of another photoelectric conversion device of the present invention.

Claims (1)

[Claims] 1. When forming a plurality of photoelectric conversion elements connected in series on a substrate having an insulating surface, a step of forming a plurality of first electrodes by a first groove in a conductive film on the substrate; a second step of forming a non-single crystal semiconductor on the first groove and the electrode region; and a second step of selectively removing the semiconductor on the first electrode to expose a part of the plurality of first electrodes. a plurality of second electrodes on the semiconductor and in close contact with the first electrodes of the second trenches;
A step of electrically connecting the first electrode and the second electrode of adjacent photoelectric conversion elements in series by forming an insulating film on the electrode of the pad; A method for manufacturing a semiconductor device, comprising the steps of: forming an organic resin on the upper surface of the entire region except for the pad region; and removing the insulating film on the pad region using the organic resin as a mask.