JPS6141156B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of metal wiring for thin film solar cells.

Conventional solar cells have been made using single crystal silicon with a PN junction formed thereon. In recent years, thin-film solar cells, which are low-cost, can be processed at low temperatures, and can be produced over a large area, have been attracting attention as they have come to be used in many applications such as watches, calculators, and radios.

FIG. 1 shows a cross-sectional view of an example of a thin-film solar cell. A NESA electrode 2 is formed on a glass substrate 1, an N-type thin film semiconductor 3 is stacked on the glass substrate 1 and the NESA electrode 2, and a P-type thin film semiconductor is further formed on the N-type thin film semiconductor 3. A PN junction is formed by stacking 4. After forming the N-type and P-type thin film semiconductors in a predetermined pattern, an insulating film 5 is formed on the entire surface, and a hole is made on the electrode 2 and the P-type semiconductor 4 to make contact with the metal wiring. After wiring 6, the structure shown in FIG. 1 is obtained.

There is a PIN-type structure in which an I-type semiconductor that is not doped with impurities is sandwiched between P-type and N-type thin film semiconductors, but for the sake of simplifying the explanation hereafter, I will not use it here.
The PN structure also includes a PIN type structure.

The film thickness of the first layer N-type thin film semiconductor and the second layer P-type thin film semiconductor in FIG. 1 is from several hundred Å to several thousand Å in the case of amorphous Si, That is, the P-type thin film semiconductor 4 is susceptible to pinholes, and if a pinhole occurs in the contact portion of the second layer thin film semiconductor 4, the metal wiring 6
This causes the PN junction to be short-circuited through the pinhole.

An object of the present invention is to eliminate the above-mentioned drawbacks and improve the yield and reliability of thin film solar cells.

FIG. 2 is a sectional view showing a thin film solar cell according to the present invention.

Nesa electrodes 2 are formed in a predetermined pattern on an insulating substrate 1. A first thin film semiconductor 3 (for example, an N-type thin film semiconductor) is formed on the entire surface of the insulating substrate 1 and the NESA electrode 2, and then patterned into a predetermined shape. A second thin film semiconductor 4 of a type different from the first thin film semiconductor (for example, a P-type thin film semiconductor) is formed on the entire surface of the first thin film semiconductor 3, the NESA electrode 2, and the insulating substrate 1, A predetermined pattern is formed in which a portion A of the semiconductor is formed between the second thin film semiconductor and the substrate in a portion where the electrode and the first semiconductor are not present.

At this time, in the lead-out portion of the electrode 2 of the first thin film semiconductor 3, it is necessary to provide a margin greater than the mask alignment error, as shown in FIG. 3, to prevent short circuit between the second thin film semiconductor 4 and the electrode 2. be.

After forming the insulating film 5 on the entire surface, a predetermined hole is made on the part A of the second thin film semiconductor so as to make contact with the metal wiring 6, and further a predetermined metal wiring 6 is formed, thereby forming the thin film of the present invention. A solar cell is formed.

Furthermore, in areas other than the lead-out portion of the electrode 2, it is necessary to cover the substrate side of each layer to prevent short circuits between the layers. 3 and 4 are an enlarged view and a plan view of FIG. 2, respectively.

As in the present invention, there is an electrode and a first layer thin film semiconductor in contact with the electrode between the second layer thin film semiconductor and the insulating substrate at the contact portion between the second layer thin film semiconductor and the metal wiring. This structure makes it possible to prevent short circuits at the contact portion, thereby improving the yield and reliability of thin-film solar cells.

In the above description of the present invention, the insulating film 5 was used as an interlayer insulating film, but according to the structure of the present invention, the interlayer insulating film 5 may not be used. Also P type and N
Even if the molds are replaced, the effects of the present invention remain the same.

There is also a PIN structure in which an I-type semiconductor not doped with impurities is sandwiched between P-type and N-type thin film semiconductors, and the effects of the present invention are the same even with this structure.

That is, at the contact portion with the electrode wiring in the thin film semiconductor of the end layer facing the substrate, at least something other than an insulator existed between the thin film semiconductor and the substrate, and the electrode on the substrate side connected to the thin film semiconductor In the lead-out part, an alignment margin greater than the alignment error is provided to prevent short-circuiting between each layer, and in parts other than the electrode lead-out part, each layer is covered with a layer on the substrate side to prevent short-circuiting between the layers.

This is similar to the PN structure.

As described above, in the present invention, a part of the second type thin film semiconductor is formed directly on the insulating substrate, and the metal wiring and the second thin film semiconductor are connected only on the directly formed part of the thin film semiconductor. Since the metal wiring material is formed using a thin film semiconductor of the second type, the metal wiring material does not penetrate through the thin film semiconductor of the second type and cause a short circuit with the thin film semiconductor of the first type. This has the effect of preventing deterioration and improving device reliability.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the structure of a conventional thin film solar cell. FIG. 2 is a sectional view showing the structure of a thin film solar cell according to the present invention. FIG. 3 is an enlarged view of FIG. 2. FIG. 4 is a plan view of FIG. 2. However, the substrate and insulating film are omitted. Each subscript is common from FIG. 1 to FIG. 4.

Claims (1)

[Scope of Claims] 1. An electrode is provided on an insulating substrate, a first type thin film semiconductor is provided on a portion of the insulating substrate and the electrode, and at least one portion of the first type thin film semiconductor is provided on the first type thin film semiconductor. In a solar cell having a second type of thin film semiconductor that overlaps with the second type of thin film semiconductor, and a metal wiring is formed on a part of the second type of thin film semiconductor, a part of the second type of thin film semiconductor overlaps with the second type of thin film semiconductor. A thin film solar cell, characterized in that it is formed directly on the insulating substrate, and the metal wiring and the second thin film semiconductor are connected only on the directly formed portion of the thin film semiconductor.