JPS60211880A - Manufacture of photoelectric conversion device - Google Patents

Abstract

PURPOSE:To prevent a change into a polycrystal by using a material mainly comprising chromium as a metal capable of forming an open groove through a mask-less process and forming a non-oxide light-transmitting conductive film by a reaction between chromium and a semiconductor. CONSTITUTION:A light-transmitting conductive film is formed extending over the upper surface of a light-transmitting substrate 1 with an insulating surface, projecting laser beams are scanned to form an opened groove 13, and electrodes 2 are prepared to each inter-element region 31, 11. Nonsingular crystal semiconductor layers 3 generating photovoltage by beam projection are shaped to the upper surfaces of the electrodes 2 and the opened groove 13. An opened groove 18 is formed extending over the left direction side of the opened groove 13, and the side surfaces 8 or side surfaces and upper surfaces 9 of the electrodes are exposed. Chromium to which silver and copper are added is laminated as metals 46, 46' on a semiconductor, and thermally treated at a temperature of 100-300 deg.C and a light-transmitting conductive film composed of the oxide of an intermetallic compound is shaped between chromium and the semiconductor. Accordingly, reflection on a chromium surface to the long-wave length beams of incident beams 10 is accelerated, the reflection of long-wave length beams is increased, and a reaction does not progress for a prolonged term, thus improving reliability.

Description

Detailed Description of the Invention The present invention comprises a plurality of photoelectric conversion elements (also simply referred to as elements) in which a non-single crystal semiconductor including an amorphous semiconductor that generates photovoltaic force upon irradiation with light is provided on a transparent insulating substrate. The present invention relates to a method for manufacturing a second electrode in a charging conversion device that is electrically connected in series and generates a high 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. The following description is based on the case where two electrodes (on the semiconductor, that is, on the side away from the substrate) are electrically connected in series.

In such a configuration, the present invention provides that the third groove for separating the second electrodes of the first element and the second element from each other is brought into close contact with the P or N type non-single crystal semiconductor layer. Compounds (mixtures) of semiconductors and metals, especially chromium.
A conductive film is formed by providing silicide and laminating chromium or a metal film containing chromium as a main component (hereinafter simply referred to as chromium) on the conductive film.

In the present invention, a second electrode conductive film provided on a semiconductor is scribed using a laser beam to form separate electrodes. At that time, in order to prevent the underlying non-single crystal semiconductor, especially the hydrogenated amorphous semiconductor, from becoming polycrystalline and becoming conductive when irradiated with laser light at a temperature as high as 1800 degrees Celsius, sublimation is required. Chromium metal, which has relatively low thermal conductivity, is laminated with a non-oxide transparent conductive film, especially chromium silicide, made by heat-treating the chromium and reacting it with the semiconductor underneath. However, by applying LS to such a conductive film, the semiconductor under the third groove is left without being removed at the same time, and polycrystallization of the semiconductor due to laser annealing in this groove is prevented. It is.

That is, conventionally, silver or aluminum, which is a light reflective metal, has been used as the back electrode. However, silver has poor adhesion and easily peels off. Aluminum reacts with the semiconductor at the interface, and the aluminum migrates into the semiconductor. For these reasons, improvements to the back electrode have been sought.

For this purpose, the present invention uses a material containing chromium as a main component as a metal capable of forming grooves by a maskless process. Furthermore, an intermetallic compound, which is a non-oxide transparent conductive film, is formed by the reaction between the chromium and the semiconductor, thereby further preventing an interfacial reaction between the semiconductor metals.

For example, chromium was formed to a thickness of 300 to 3,000 layers on a non-single crystal semiconductor. Then, chromium becomes heat resistant (melting point 18
00°C, boiling point 2660'C) and has sublimability to laser light, and has a boiling point of 100 to 300°C, typically 200°C.
It is extremely stable even if it reacts with the underlying silicon material by heat treatment at a temperature of It has been experimentally found that it is possible to construct ha/fa. Furthermore, the resistance of the ohmic contact with the N- or P-type semiconductor layer was also low, which was highly desirable.

The details of the invention are shown below in accordance with the drawings.

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

In the drawing, a transparent substrate (1) having an insulating surface, for example, a glass plate (for example, thickness 0.5-2, 2mm+for example, 1
．． 2 mm (in the drawing, the length is 60 cm in the left and right direction) and the width is 20 cm). Further, a light-transmitting conductive film such as ITO (indium oxide/tin oxide mixture, i.e., a film in which 10% by weight of soot is added to indium oxide) is applied over the entire upper surface.
~400 people) or a transparent conductive film whose main component is tin oxide doped with a halogen element such as fluorine (1500~200 people)
00 persons) was formed by a sputtering method, particularly a magnetron sputtering method, a vacuum sputtering method, a LI'CVD method, a plasma CVD method, or a spray method.

After this, WAG laser processing tfi! (Made by Nippon Laser)
Depending on the wavelength (1.06μ or 0.53μ), the average output is 0.
An open groove was formed by applying 1 to 3 W (focal length Mtt 40 mm) using a Q switch. This spot diameter is 20-70
μφ was typically controlled to 50 μφ by a microcomputer. In this way, the CTF is scanned with this irradiated laser beam, and the first open line, which is the scribe line, is scanned. ! (13) was formed, and the first electrode (2) was produced in each inter-element region (31), (11).

The first open groove (3) formed by this first LS was approximately 50 μm wide and 20 cm deep to completely cut and electrically isolate each electrode of the first CTF.

After that, a non-single crystal semiconductor layer (3) that generates photovoltaic force by light irradiation is formed on the upper surface of the electrode (2) and the groove (13) by plasma CVD or LPCVD.
It was formed to an average thickness of 1.0μ, typically 0.7μ.

A typical example is a P-type semiconductor (SixC1-) < x=0.
8 about 200 people) - Type 1 amorphous or semiamorphous silicon semiconductor (about 0.7 μ) - N type microcrystal (
500 people), and on top of this, 5i
Non-single-crystal semiconductor or P-type semiconductor (SixC+-x) -1 type, N-type, P-type St semiconductor - I Tandem type PrNPIN having two PIN junctions and one PN junction made of type 5ix Ge l-x semiconductor-N type Si semiconductor, ...
3).

Furthermore, as shown in FIG. 1(B), a first open groove (1
A second open groove (18) was formed over the left side (first element side) of 3) by the second LSI process.

In this drawing, the first and second open grooves (13), (18)
The centers of the two are shifted by 100μ. The linear groove was provided without cutting the semiconductor at the peripheral portion.

That is, the second groove was provided in a straight line inside the semiconductor. This structure was effective in preventing short circuits between the first and second electrodes in the peripheral view.

Thus, as shown in FIG. 1(B), the second open groove (18
) is the side (8) or side and top surface (9) of the first electrode (
1110~5μ) was exposed.

Furthermore, this substrate was coated with diluted #I (1/10 liver prepared by diluting 48% IIF with 10 times water was used here) for 10 seconds.
Etching was performed for 1 minute, typically 30 seconds.

Then, during LSO, the semiconductor (3) and CTF (2) were able to remove low-grade porous silicon oxide produced by reacting with oxygen in the atmosphere.

The properties of chromium, which was studied as a metal (46) and <46'> on a semiconductor, are as follows.

Melting point Boiling point Thermal conductivity ('C) ('C) cal / (cm sec d
eg) Cr 1900 2640 0.2 In other words, chromium ("
5)', Mini AI is 0.487. Ag is 0.998
> is e (extremely excellent as an electrode material for laser processing of the present invention. Namely, gold and aluminum are 60%
If it is more than 0 Å, the heat conduction in the lateral direction (film direction) will be large, and not only will the irradiated area not be heated to a sufficiently high temperature, but it will easily react with the semiconductor underneath, and the heat will cause the semiconductor to become polycrystalline. It turns into Further, the third trench easily penetrated the semiconductor layer and also damaged the first conductive film.

Further, since nickel does not have sublimation properties, laser processing is not preferable like aluminum and other materials.

For this reason, it has been found that a two-layer film of a non-oxidizing conductive film and chromium is particularly excellent on a semiconductor.

In order to improve the low optical reflectance of chromium and thus improve the conversion efficiency of the device, 0.1 to 50% by weight of copper or silver, for example 2.0 to 10% by weight, is added to Cr.

(1) Cr (300-5000 people), (2) Cr
-Cu (2.5% by weight) (300-5000 people) (3
) Cr-8g (2.5% by weight) (300-5000 people) was excellent in LS processability.

When using chromium (1) in these back electrodes, the semiconductor underneath is also completely removed by LS, resulting in a high manufacturing yield. However, because of its low reflectance, its long-wavelength light characteristics are poor.

On the other hand, (2) and <3) chromium added with silver and copper can improve the light reflectance by 5 to 20% compared to chromium alone, making it ideal for laser processability as there is no particular problem. Met.

Next, the entire laminate is heated to 100 to 300°C, for example, 200°C.
Heat treatment (30 minutes to 3 hours) was performed at a temperature of . Then,
It was possible to form an intermetallic compound (mixture) between the chromium and the semiconductor as a non-oxide transparent conductive film with a thickness of 30 to 100 mm.

This transparent conductive film promotes reflection of long wavelength light of the incident light (10) on the chrome surface, increases the reflection of long wavelength light,
It can have a light confinement effect. In addition, once this conductive film is formed, the reaction does not proceed even after long-term use, which is effective in improving reliability.

In addition, it has many features such as being able to prevent large damage to the underlying semiconductor during laser processing in the next step and prevention of polycrystallization caused by laser annealing.

Next, in FIG. 1(C) of the present invention, the third open groove (20) is inserted into the third groove so that the chromium (45) constituting the second electrode and the connector (30) do not electrically short-circuit. It was provided over one element region (31).

That is, the electrode where the open circuit voltage of the first element is generated <39).

(38) The electrical separation between
(typically 50 μφ) from the second open groove (18) by about 10 mm.
They were formed with a spacing of 0μ. That is, the third open groove (20)
The center of the second open groove (30) is 100~2
00μ is typically provided at a depth of 50μ over the first element side.

This LS simultaneously removed chromium and the underlying non-oxide conductive film. In this drawing, the upper surface of the semiconductor has the same flat surface as the portion not irradiated with laser light.

However, by performing ultrasonic cleaning with acetone after this LSO, the I
It was possible to achieve a resistance of more than OKΩ/cm (resistance of IKΩ per 1 cm length).

FIG. 1(C) shows such a drawing.

LS selectively removed not only the chromium but also the underlying layered product (mixture) of silicon and chromium. However, even when laser Raman spectroscopy is performed on a non-single-crystalline semiconductor whose main component is silicon, no particularly polycrystalline IIJi direction is observed, indicating that sufficient isolation can be achieved in this open groove (20). found.

Furthermore, the semiconductor layer under this open groove (20) is
Thermal oxidation was performed for 30 minutes in an oxidizing atmosphere at, for example, ~200°C.

At the same time, the exposed silicon in the groove (20) is oxidized to form a solid phase of silicon oxide (34) to a thickness of 100 to 500 mm.
Formed by gas phase reaction. Thus two (7) ffi
2 (7) Crosstalk between electrodes (39) and (38) was further prevented.

Thus, as shown in FIG. 1(C), a plurality of elements (
31), <11) were able to be directly connected at the connecting portion (12) formed by connecting the underlying CTF and chromium.

FIG. 1(D) shows an attempt to further complete the present invention as a photoelectric conversion device, that is, a silicon nitride film (21) with a thickness of 500 μm was formed by a plasma vapor phase method as a passivation film.
It was formed uniformly to a thickness of ~2,000 mm to further prevent leakage current between each element due to adsorption of moisture, etc.

Furthermore, an external lead terminal was provided at the periphery &1t (5).

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

In this way, the photovoltaic force generated by the irradiation light (10) is transmitted from the bottom contact to the first element of the first element as shown by the arrow (32).
The current flowed from the electrode to the second electrode of the second element, making it possible to connect them in series.

As a result, on this substrate (60cm x 20cm), each element had a diameter of 14.35mm in the middle, a connecting part of 11150μ, an external extraction electrode part of +1]10mm, and a peripheral part of 4mm, so that there were essentially 40 stages within 580mm x 192mm. , an effective area (192 mm x 14.35 mm, 40 stages, 1102 ctA, or 91.8%) could be obtained.

If the segment has a conversion efficiency of 10.3% (1.05cm), the panel will have a conversion efficiency of 7.3% (theoretically 9.0%, but the effective conversion efficiency will be reduced by the resistance of the 40-stage connection). Reduced XA old (roomW/cat)
), it was possible to have an output power of 7.8-.

Furthermore, when this panel was subjected to a high temperature storage test at 150° C., a decrease of 10% or less was observed after 1000 hours, for example, when the number of panels was 20, only X = 1.3%.

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

Also, this panel for example 40cm x 60cm or 6
Packaged by combining 2 pieces, 4 pieces or 1 piece of 0cm x 20cm, 40cm x 120cm in an aluminum sash or carbon fiber frame, 120cm
It is possible to provide a NEDO standard high power panel of m x 40 cm.

In addition, this NEDO standard panel can be bonded with a fluorine-based protective film using Seaflex on the reflective surface side (upper side in the drawing) of the photoelectric conversion device of the present invention to increase mechanical strength against wind pressure, rain, etc. It is valid.

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 polyimide resin, 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 embodiments described above, it is particularly effective because 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. Met.

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, chemically strengthened glass with a thickness of 1.1 as the transparent substrate (1)
1III11, length 60 cm, width 20 cm was used.

A silicon nitride film was applied to the top surface to a thickness of 0.1 .mu.m to form an L7 blowing layer.

Furthermore, IT with CTF on top of that 01600 people + 5nOL
300 people were fabricated by electron beam evaporation.

Thereafter, a first groove was formed using a YAG laser with a spot diameter of 50 μm and an average output of 0.7 − controlled by a microcomputer at a scanning speed of 0.3 m/min.

Furthermore, the edge of the panel is connected to the laser beam with an average output of 0. First at the heel
The electrode semiconductor was scanned in a rectangular manner 5111 m inside from the edge of the glass to prevent an electrical short circuit with the frame of the panel. The element region (31), <11) was set to be within 15 mm.

Thereafter, a non-single crystal semiconductor having one PIN junction as shown in FIG. 2 was manufactured by a known PCVD method.

Its thickness was approximately 0.7μ.

After this, the first element (31) is removed by 100μ from the first groove.
was shifted, and a second open groove (18) was produced as shown in FIG. 2(B) by LS in the atmosphere with a spot diameter of 50 μφ and an output IW.

Further, on this upper surface, chromium was formed to a thickness of 1000 mm using the magnetron DC spaft method, and a second electrode (4
A 5-input connector (30) was configured.

Then, the sheet resistance of chromium is 1Ω/at a thickness of 1000 people.
I was able to get my mouth. The sheet resistance of the first electrode is 25
It was possible to obtain a value of 1 oΩ/mouth or less, which is sufficiently lower than Ω/mouth. The manufacturing method is as follows.

Magnetron DC sputtering Cr1lli characteristics achieved Static gas introduction DCPoner Substrate Sputtering vacuum Degree of vacuum V Temperature Time (torr) (torr) (VXA) (''C)
(sec,) 1 6 xlO-' l xlO-347
01100130(180)2 1XIO-5〃〃I
R,T 130 (120)3 7x10-G 5xl
O-33951,,19" 120 (120) (Distance between substrate target 75mm) Film characteristics Rsheet (Ω/mouth) Th1ckness (person) 1 0.99~1.15 1100 2 0.98~1.15 1500 3 3.06~4.51 1000 Furthermore, perform heat treatment (200℃, 30 minutes) in an oxidizing atmosphere, and add 50% of chromium silicide between the chromium and the semiconductor.
Formed to the thickness of a person.

Furthermore, the third opening ti (20) is similarly changed to the third LS.
Using AG laser, 0.6 W (scan speed 3
The first element (31
) side, and FIG. 1(C) was obtained.

Thereafter, a pansivation film (21) was formed using PCVD to form a silicon nitride film to a thickness of 1,000 mm at a substrate temperature of 200'C (film formation time: 30 minutes).

As a result, it was possible to create 40 stages of 15 mm elements on a 20 cm x 60 cm panel.

The effective efficiency of the panel is 8Ml (100mW/c+1
I was able to obtain a score of 7.3% and an output of 1.

Effective area is 1102cm! 91. of the entire panel.
8% could be used effectively.

In this example, as shown in FIG. 1(D), by overlapping the upper protective organic resin (22),
It has a structure in which a photoelectric conversion device is sandwiched between organic resin sheets, has flexibility, and can be mass-produced at extremely low cost.

In FIG. 1, light was incident from the lower transparent 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.

Further, in the present invention, the chromium may be covered with a nickel film for soldering or a multilayer film of other metals, and another feature of the present invention is that the main component of the metal as a whole is chromium. Furthermore, it is also effective to use a metal whose main component is chromium, in which other metals such as Cu or silver are added in an amount of 50% (by weight) or less.

Further, the present invention mainly uses chromium silicide. However, other intermetallic compounds may be used as long as they are sublimable metals that can be laser processed. In addition, in the present invention, the thickness of the chromium film may be 10 to 100 mm, and indium oxide (including ITO) may be formed on the top surface to a thickness of 200 to 2000 mm. In such cases, chromium silicide was formed using all the chromium. Then, the subsequent transparent conductive film of chromium silicide can act as a highly reliable buffer layer between ITO and the semiconductor.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view showing the manufacturing process of the photoelectric conversion device of the present invention. Patent applicant: Semiconductor Energy Research Institute Co., Ltd. Representative: Shunpei Yamazaki

Claims (1)

[Claims] (1) A first electrode of a transparent conductive film on a substrate having an insulating surface, a non-single crystal semiconductor that generates a photovoltaic force by light irradiation on the electrode, and In the method for manufacturing a photoelectric conversion device in which a plurality of photoelectric conversion elements each having a second electrode are electrically connected in series and arranged on the insulating substrate, chromium is mainly contained on a non-single crystal semiconductor. a step of forming a compound (mixture) of the semiconductor and the metal film at the boundary by heat treatment at a temperature of 100 to 300°C; and after the step, forming a compound (mixture) of the semiconductor and the metal film; and a step of forming an open groove by irradiating and removing the metal film with a laser beam, thereby electrically separating the second electrodes of adjacent elements from each other. 2. In claim 1, the non-oxide transparent conductive film mainly contains a mixture (compound) of chromium and silicon, and the chromium on the upper surface 1. A method for manufacturing a photoelectric conversion device, characterized in that a metal containing as a main component is formed by a sputtering method and has a sheet resistance of 10 Ω/unit or less.