JPS62162368A - Fabrication of semiconductor device - Google Patents

Abstract

PURPOSE:To contrive the improvement of a withstand voltage by filling an organic insulator in cavities or pinholes of an non-single crystal semiconductor comprising a PIN junction and applying a reverse bias to cure the positions where short or leakage is easy to occur. CONSTITUTION:A transparent electrode 2 of ITO+SnO2 is arranged on a glass plate 1 and is cut 13 by laser processing so as to form a non-single crystal semiconductor layer 3 of P-type Si0.8C0.2 (thickness 50-150Angstrom ) - I-type amorphous Si (0.4-0.9mum) - N-type fine crystal (200-500Angstrom ), for example. When the layer 3 is formed, cavities 6 and pinholes 6' are produced due to deposition, detachment etc. of slices. Then, a positive photoresist is spread to fill 7, 7' said cavities and pinholes, followed by exposure and development. After removing unnecessary resist wholly, fixation is done by sintering. The layers 3 and 2 are cut 18 by a laser and an electrode 4, for example, of ITO+Al is evaporated and those are isolated 20. Subsequently, when the substrate is heated up to about 150 deg.C and is applied a reverse bias voltage in a predetermined circuit 30, leakage points are cured one by one and a reverse withstand voltage as that of a photoelectric conversion device increases.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a semiconductor device, for example, a photoelectric conversion device using a non-single crystal semiconductor including an amorphous semiconductor that generates a photovoltaic force, when forming the non-single crystal semiconductor. The voids or pinholes that are involuntarily formed are organically filled with @It materials, and the surface electrodes are short-circuited or weakly leaked to each other due to the voids or pinholes (hereinafter also referred to as pinholes). In addition, by applying a bias voltage between the pair of electrodes, the weak breakdown voltage portion of the non-single crystal semiconductor that is easy to break can be cured, which improves the characteristics of the semiconductor device. The present invention relates to a method for manufacturing a semiconductor device that aims to improve, for example, "improve photoelectric conversion efficiency."

This invention cures sheet or leak-prone areas by filling such voids or pinholes with an organic insulator and applying a reverse bias to a non-single crystal semiconductor having a PIN junction, etc. In particular, it has "improved reverse breakdown voltage" as a photoelectric conversion device.

During long-term use of this photoelectric conversion device, the material of the back electrode gradually impregnates inside the semiconductor through the pinholes, preventing short circuits between electrodes with high voltages above and below, and improving reliability, especially photoelectric conversion. This is intended to "prevent a reduction in conversion efficiency" of the conversion device.

Conventionally, a photoelectric conversion device (hereinafter simply referred to as a device), that is, a device in which a plurality of elements are arranged on the same substrate and integrated or hybridized, is disclosed in, for example, Japanese Patent Laid-Open No. 55-4994. Japanese Patent Application Laid-Open No. 55-124274 and Japanese Patent Application No. 54-90097/90098/90099 filed by the present inventor (filed on July 16, 1982) are also known.

As an example of a conventional invention, FIG. 1 shows a vertical cross-sectional view of a photoelectric conversion device manufactured by a mask alignment method.

In the drawings, a transparent substrate (e.g. glass TFFL) (1
), a transparent conductive film (abbreviated as CTF) (2) constituting the first electrode, a semiconductor layer (3), and a second electrode (4) made of aluminum are laminated. ing.

In the conventional example shown in Figure 1, the aluminum (4) is the semiconductor (3).
) to convert this integrated photoelectric conversion device into 150
When I left it accelerating at 'C, it deteriorated in several tens of hours. Therefore, the electrode was completely unsuitable for actual outdoor use.

Therefore, in order to improve such thermal reliability, a transparent conductive film such as ITO is placed under the aluminum electrode on the back surface.
A two-layer structure is known in which ITO (indium tin oxide) is provided on a semiconductor, and aluminum is further provided on top of the ITO.

With such a structure, thermal reliability can be significantly improved because ITO can prevent aluminum from reacting with the semiconductor.

However, when forming this conductive film, this light-transmitting conductive film has a strong tendency to attract foreign particles, so if voids or pinholes are formed in the semiconductor, they may get inside the pinholes. However, a short circuit or a leak occurred between the first electrode on the lower side and the second electrode on the upper side, making it impossible to put it into practical use.

For this reason, conventionally in the formation of this non-single crystal semiconductor,
It can be put to practical use only in small-area photoelectric conversion devices where pinholes or voids are unlikely to exist, for example, photoelectric conversion devices for consumer calculators such as 1 cm x 4 cm, and 10 cm x 1.
In photoelectric conversion devices with a large area of 0 cm or more, these voids or pinholes always exist in the active semiconductor region, so a structure in which a transparent conductive film is formed on the semiconductor as part or all of the back electrode is required. It was impossible to use it.

The present invention provides extremely effective means for industrially solving these problems.

In other words, by selectively filling only these pinholes with an insulating material, the first electrode on the lower side and the second electrode on the upper side of the semiconductor can be connected even if the transparent conductive film has strong dust. This prevents short-circuiting or leakage even when used. Furthermore, for semiconductor devices in which pinholes etc. are filled with this insulator, especially organic insulator,
Apply bias voltage. Then, in a semiconductor device that has not been completely improved even by filling with an organic substance, it is possible to "heal" a location where a leak current has locally flowed.

The following steps can be presumed to be the reason for this healing.

That is, by applying a bias voltage, particularly a reverse bias voltage, current flows intensively only at the leakage location, causing abnormal heat generation at that location. Due to this heat generation, the filled organic resin or this resin reacts with the semiconductor, and becomes an insulator. This leakage point is cured by this insulating material. Such a process heals the weaker spots and then the slightly weaker spots. This process is automatically repeated by temporarily increasing the bias voltage. It is thus presumed that all leak-prone points can be cured and the entire device can be made to have properties equivalent to a normal semiconductor device with substantially no holes or pinholes.

Examples are shown below.

Example 1 FIG. 2 is a longitudinal sectional view showing the manufacturing process of the present invention.

In FIG. 2 (A), a transparent substrate (1), for example, a glass plate (for example, 1.2 mm thick, the length is in the left and right direction in the drawing)
10 cm, rll 10 cm). A translucent organic resin film substrate may also be used. Furthermore, a transparent conductive film (CTF), for example, ITO, is applied to the entire upper surface.
(1500 people)+SnO□ (200-400 people) or a transparent conductive film mainly composed of tin oxide or tin nitride added with a halogen element (1500-2000 people) using vacuum evaporation, LPCVD, or plasma CVD. It was formed by a method, a spray method, an ECR method, or a sputter method.

After that, the microcomputer is controlled to irradiate the substrate with a YAG laser processing machine (wavelength 1.06μ or 0.53μ) from the bottom or top of the substrate for patterning (1
3) was formed.

The opening formed by patterning had a width of about 50 μm and a length of 10 cm, and the width of each element (31) and (11) was 10 to 20 mm. The CTF (2) constituting the first electrode was thus cut and separated to form open grooves. Thereafter, a non-single crystal semiconductor layer having a PN or PIN junction is formed on the upper surface by a plasma CVD method including a glow discharge method and an ECRCVD method or a photo CVD method.
μ is typically formed to a thickness of 0.5 to 0.7 μ.

A typical example is a P-type semiconductor (SixC+-x x=0.8
Thickness 50-150) - Type 1 amorphous or semi-amorphous silicon semiconductor (0,4-0.9μ) - Non-single with one PXN junction consisting of a semiconductor with microcrystals of the N type (200-500) A crystalline semiconductor (3) was obtained.

Or P type semiconductor (SixC, -x) I type amorphous silicon semiconductor - N type silicon semiconductor - P type 5i
xC+-x semiconductor-■ type 5ixGe+-x (x=0.5
) - Tandem type PINP such as N-type silicon semiconductor (300-1000 people)! N...PIN junction semiconductor may be used.

Such a non-single crystal semiconductor layer (3) was formed to have a uniform thickness over the entire surface.

However, this semiconductor (3) has flakes (
A large number of holes (6) and pinholes (6") are unintentionally present due to reasons such as snowflakes) adhering to the film and detaching after the film is formed.The number of holes (6") and pinholes (6") are found in the dark field image using a microscope with a magnification of 100x. As many as 2 to 4 individuals may be observed per 10 field of view.

For this reason, the method of the present invention first involves this pinhole etc. (6).
(6') was selectively filled with an insulator. The work is shown below.

After forming the semiconductor (3) shown in FIG. 2(A), this semiconductor was coated with a photosensitive organic resin. At this time, care was taken to ensure that the organic resin sufficiently impregnated into the pinholes and the like. As this photosensitive organic resin, a photoresist, for example, a positive type photoresist such as 0FPR-800 sold by Tokyo Ohka Co., Ltd. was used. This photosensitive organic resin is formed on the entire surface of the semiconductor and in the pinholes and voids to a thickness of 0.1 to 5 μm using a spinner, coater or spray method.

For example, when using a spinner, adjust the resist to 50Orpm.
The coating was performed for 5 seconds and at 2000 rpm for 30 seconds. Furthermore, this coated organic resin film is pre-baked (85℃,
40 minutes). Furthermore, as a development process, ultraviolet light (wavelength 300 to 400 nm) (17) is applied from this resist side.
was irradiated to immobilize the organic resin filled in the pinholes, etc. of this photosensitive organic resin, and further to unimmobilize the organic resin on the semiconductor surface. Is this condition 0FPI? -8
When using 00, ultraviolet light was applied at 6 mW/cm" for 5 seconds, and a predetermined developing process was performed.

Furthermore, the whole was rinsed (with pure water for 10 minutes) by a known method. Then there is a pinhole (6).

Non-immobilized organic resin other than the organic resin film fixed within (6゛) can be dissolved away. That is, all the organic resin on the semiconductor (3) can be removed. Furthermore, post-baking (150°C for 1 hour) was performed to chemically stabilize the organic resin (7), (7'') filled inside the exposed pinhole.Then, as shown in Figure 2 (B). Thus, only the pinholes (6) and (6') can be selectively filled with the organic resin insulators (7) and (7').

The upper surface of this insulator can be filled so as to be approximately coincident with the upper surface of the semiconductor, or to a lesser extent (due to volume contraction during post curing, etc.).

Furthermore, as a next step, as shown in FIG. 2(B), a second open groove (18) was formed to the left of the first open groove (13) by a second laser scribing process. This laser scribing was performed by irradiating the substrate (1) from above.

In FIG. 2, a conductive film (4) for the back electrode is further formed on this upper surface as shown in FIG. 2(C), and an opening i (20
) was established.

When this second electrode is of a light transmission type, the light transmission conductive film is made of 300 to 5000 layers, such as ITO (indium tin oxide) or I'nzOz (indium oxide).

SnO□ (tin oxide), ZnO (zinc oxide), etc. were formed to form a second electrode. In such a structure, long wavelength light can be emitted toward the back surface (upward in the drawing).

Furthermore, in the case of using an optical confinement method, a reflective electrode may be further provided on the upper surface of the transparent conductive film. Aluminum, chrome, silver, aluminum (300~5
A single-layer metal film or a double-layer metal film of aluminum and nickel was formed as a second electrode (4).

In this drawing, for example, a two-layer conductive film of 1,050 layers of ITO and 1,000 layers of aluminum is used as the second electrode (4).

These methods use sputtering, electron beam evaporation, or plasma CVD, and in order to avoid deteriorating the semiconductor layer,
It was formed at a temperature below .degree.

Thus, as shown in FIG. 2(C), a plurality of elements (3
We were able to create a photoelectric conversion device in which 1) and (11) were connected in series at the connecting part (12).

Furthermore, after this, using the circuit configuration shown in FIG. 3, the circuit shown in FIG.
For photoelectric conversion devices connected in series as shown in
A bias voltage, especially a reverse bias voltage, is applied. This process of applying a bias voltage and curing was performed by heating within a range from room temperature to a temperature that does not cause thermal breakdown of the semiconductor (generally 150° C.). That is, each photoelectric conversion device (31), (11) of the integrated photoelectric conversion device (22)
) is composed of one diode (25) and a resistor (26) indicating a leakage or short-circuit location due to a hole or pinhole. A Zener diode (23) was placed in parallel with this element so that a Zener current flows at a voltage slightly lower than the reverse breakdown voltage of the PIN characteristic of a normal element. This can prevent a bias voltage higher than this Zener voltage from being applied to one element. Furthermore, by arranging Zener diodes in parallel with each element (31) and (11), it is possible to prevent a current that would induce permanent destruction from flowing into the healed area after one weak point has healed. . With the bias skew circuit device thus formed, the DC voltage (24) can be increased from Ov to 120V (here, the element is 15V).
Since the two were connected in series, the voltage was applied up to 120V).

An example of the results is shown in FIG.

Then, the bias voltage V R1 in this photoelectric conversion device
1 (V) and the current I*s(m^) flowing here, when the application is started, the trajectory shown by the curve (30) is followed. Then, the first defective leak occurs at (30-1). However, when this leakage current increases, the leakage current decreases again due to the curing effect.

When the bias voltage is further increased, the leakage current increases again at (30-2). However, it decreases again due to the cure effect. Furthermore, this is (30-3)...(30
-m) is repeated, resulting in the so-called characteristic (32) in which all the photodiodes operate normally. After this, when this bias voltage is lowered, the loci (33), (30')
The current becomes OmA. That is, the return trajectory can make the leakage current sufficiently smaller than the initial state (30).

Just to be sure, when voltage is applied again to this photoelectric conversion device, it passes through the curve (30'') and obtains the characteristic of reverse breakdown voltage at (34).In other words, the weakly damaged parts have been healed.
This healed area will never deteriorate again.

The photoelectric conversion device (23) is equipped with a photoelectric conversion device (23) as shown in FIG.
After removing the bias cure circuit, irradiation light (10) is applied. A board like this example (10 cm x 10
cm) integrated photoelectric conversion device panel with AMIC
When irradiated with 100m/cm”), the open circuit voltage is 1
It was possible to provide an output of 2.934V, fill factor 0.6641, short circuit current 79.34mA, current speed 17.290 (mA/cm2), and conversion efficiency 9.90χ.

However, if you use exactly the same process but omit the healing process by applying a reverse bias voltage to the bias voltage after filling with the organic resin of the present invention shown in Figure 2(C), you will only get the following conversion efficiency. I can't.

That is, sample 1 has the characteristics of a sample in which filling with organic resin is also omitted. Sample 2 is a case in which organic matter is filled, but the reverse bias curing process is not performed.

Sample 1 Sample 2 Open voltage 11.49V 12.315 Fill factor 0.471 0.597 Short circuit current 53.7
mA 79.34mA Conversion efficiency 4.43χ
8.33X Comparison with these low conversion efficiencies shows how effective filling the pinholes of the present invention with an organic resin and performing reverse bias skewing is effective in obtaining high conversion efficiencies.

Example 2 FIG. 5 is a longitudinal sectional view showing another manufacturing process of the present invention.

In FIG. 5(A), a non-transparent substrate has an insulating surface in which an inorganic insulating film (41) such as a heat-resistant organic resin or enamel is formed on a conductive stainless steel foil (40) with a thickness of 10 to 100 μm. was used. Furthermore, a conductive film for the lower electrode is applied to the entire upper surface, such as chromium (200), aluminum (1500), 5nOz (200 to 400).
0 people), aluminum (1500 people) + 5nJ4 (5
00 people) or a transparent conductive film whose main component is tin oxide or tin nitride added with a halogen element (1500~2
000 people) by vacuum evaporation method, LPCVD method, plasma CV
It was formed by D method, spray method, or sputtering method.

Thereafter, under the control of a microcomputer, irradiation was performed using a YAG laser processing machine (wavelength: 1.06μ or 0.53μ) to form patterning grooves (13).

The open groove formed by patterning had a width of about 50 μm and a length of IQ cm, and the width of each element (31) and (11) was 10 to 20 IIIll. Thus, the conductive film (2) constituting the first electrode was cut and separated to form an opening.

Thereafter, a non-single crystal semiconductor layer having a PN or PIN junction is deposited on the upper surface by a plasma CVD method or a photo-CVD method similar to that in Example 1, including a glow discharge method or an ECR discharge method, in a typical thickness of 0.2 to 1.0 μm. was formed to a thickness of 0.5 to 0.7 μm. A typical example is an N-type semiconductor (200 to 50
0 people) - I-type amorphous or semi-amorphous silicon semiconductor (0.4-0.9μ) - P-type semiconductor (Six
A non-single-crystal semiconductor (3) having one old P junction was made of a semiconductor having gradually laminated layers of C, -, x=o, s thickness of 50 to 150 layers.

A tandem type NIPNIP...NIP junction semiconductor may be used.

The non-single crystal semiconductor layer (3) was formed to have a uniform thickness over the entire surface and to have a flat or uneven texture structure.

However, this semiconductor has flakes (snowflakes) during film formation.
Pores (6
), many pinholes (6゛) are present unintentionally. The number was determined by observing a dark field image magnified 100 times using a microscope. As a result, as many as 2 to 4 objects may be observed per 10 fields of view.

Therefore, in the present invention, the pinholes (6) and (6') that are undesirably present are selectively filled with an organic insulating material in the same manner as in Example 1.

That is, after forming the semiconductor shown in FIG. 5(^), this semiconductor was coated with a photosensitive organic resin. At this time, care was taken to ensure that the organic resin sufficiently impregnated into the pinholes and the like. As this photosensitive organic resin, a photoresist, for example, a positive type photoresist such as 0FPR-800 sold by Tokyo Ohka Co., Ltd. was used. After that, the same treatment as in Example 1 was performed.

As shown in Figure 5 (B), there is a pinhole (6).
, organic resin insulator (7) is selectively applied only to the portion (6').

(7゛) can be filled.

Furthermore, as a next step, as shown in FIG. 5(B), a second opening (18) was formed to the left of the first opening (13) by a second laser scribing process. This laser scribing was performed by irradiating the substrate (1) from above.

Thereafter, a second electrode (4) was formed using a transparent conductive film using a metal mask. That is, this second electrode is made of a transparent conductive film (23) of 300 to 1400 people, for example, ITO (indium tin oxide), InzO, (indium oxide), SnO□ (tin oxide), ITN ( Indium nitride/tin nitride) (a mixture of indium nitride and tin nitride).

These are designed to prevent a conductive film from being formed in the open groove (20).
A metal mask is placed on the semiconductor shown in FIG. 5(B) in advance, and then a transparent conductive layer is formed using a sputtering method, an electron beam evaporation method, or a plasma CVD method at a temperature of 300° C. or less that does not deteriorate the semiconductor layer. A film was formed.

Thus, as shown in FIG. 5(C), a plurality of elements (3
We were able to create a photoelectric conversion device in which 1) and (11) were connected in series at the connecting part (12).

FIG. 5(D) shows an attempt to further complete the present invention as a photoelectric conversion device. That is, as shown in FIG. 3, a bias cure circuit device was used to apply a reverse bias to each element, and bias steering was performed.

After that, this circuit was removed and the photoelectric conversion device panel integrated with the substrate (10cm
/cm"), open voltage 12.618 Fill factor 0.672 Short circuit current 79.710mA Current density 17.371mA/cm" Conversion efficiency 9
．． It was possible to have an output of 82X.

However, if the exact same steps are used but only the step of filling the organic resin of the present invention shown in FIG. 5(B) is omitted, only the following conversion efficiency of Sample 1 can be obtained. In addition, the results of sample 2 can be obtained by performing only the step of filling the organic resin. That is, Sample 1 Sample 2 Open circuit voltage 6.54V 11.30V Fill factor 0.368 0.626 Short circuit current 75
．． 69mA 79.4 mA conversion efficiency 3.4
8% 8.16χ From these results, it can be seen how effective it is to fill the pinholes with an organic resin and perform bias curing according to the present invention.

More importantly, by filling the pinholes of the present invention with an insulator, there is little variation among samples of photoelectric conversion devices in the initial state, and the manufacturing yield is high. For example, in Example 1, 10 cm
Even if we made 10 mouths, we were able to obtain a σ (dispersion) of 0.195 (only 9.63χ).

Even if the semiconductor of the present invention is the photoelectric conversion device shown above,
Even larger, e.g. 40cm x 20cm, 6
0cm x 40cm or 120cm x 40cm is 6
It is possible to provide a 120 cm x 40 cm NEDO standard panel packaged with 1, 2 or 1 aluminum sash.

Further, the semiconductor of the present invention is effective not only for photoelectric conversion devices but also for diode arrays such as image sensors and nonlinear elements for thin film displays. Furthermore, the method of filling a semiconductor device with an organic resin and applying a reverse bias does not necessarily require that the bias be applied only between the overlapping upper and lower electrodes. For example, in an insulated gate field effect semiconductor device, such an active element may be cured by applying an electric field to the source, drain, and gate. It is also effective for filling pinholes in light emitting elements having double heterojunctions and super lattice structures.

This light-emitting element has a PIN junction, and this ■-type semiconductor has an extremely wide energy band width Eg) -N (narrow Eg)
-ga, N-1-N, -N-...- (thickness 5-100
It has a super lattice structure (human). In such a multilayer structure, a single pinhole destroys all the bonds, so the application of the method of the present invention is extremely effective.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view of a conventional photoelectric conversion device. FIG. 2 is a longitudinal sectional view showing the manufacturing process of the photoelectric conversion device of the present invention. FIG. 3 shows an electric circuit device for carrying out backward bias skewing of the insulator filling according to the present invention. FIG. 4 shows the characteristics obtained during the reverse bias skew according to the present invention. FIG. 5 is a longitudinal sectional view showing the manufacturing process of another photoelectric conversion device of the present invention.

Claims (1)

[Claims] 1. A step of forming a first electrode on a substrate having an insulating surface, a step of forming a non-single crystal semiconductor having holes or pinholes on the electrode, and a step of forming a non-single crystal semiconductor having holes or pinholes on the electrode; a step of filling an organic resin inside the pinhole, a step of forming a second electrode on the semiconductor and the organic resin, and after the step,
A method for manufacturing a semiconductor device, characterized in that a defective portion in the semiconductor is cured by applying a bias voltage between the first and second electrodes. 2. A method for manufacturing a semiconductor device according to claim 1, wherein the non-single crystal semiconductor has at least one PIN junction, and a reverse bias voltage is applied to the junction. 3. The method of manufacturing a semiconductor device according to claim 1, wherein the semiconductor is heated and maintained at a temperature that does not induce thermal breakdown when applying the bias voltage.