JPS60253266A - Semiconductor device - Google Patents

Abstract

PURPOSE:To give a conductive film flexibility to a certain extent as a coating for an electrode, and to give the conductive film adhesive properties with a semiconductor or a light-transmitting conductive film by forming the conductive film onto the semiconductor or the light-transmitting conductive film on the semiconductor by using a chromium alloy, to which copper or silver is added, a Cu-Cr alloy or an Ag-Cr alloy. CONSTITUTION:A second conductive film 25 is formed onto the surface of a light-transmitting conductive film CTF by a metallic film mainly comprising chromium to which copper is added. The whole is cut and isolated by LS, a plurality of second electrodes 39, 38 are shaped through isolation, and third opened grooves 20 are obtained. A laminate consisting of CTF15 and the chromium alloy 25 or a single layer body only of the chromium alloy is used as the second conductive film 5. ITO being in ohmic-contact excellently with an N type semiconductor is employed as the CTF at that time. A chromium alloy to which 0.1-50wt% copper or silver is added is used as the chromium metal.

Description

Detailed Description of the Invention "Field of Industrial Application" This invention forms a chromium alloy on the upper surface of a semiconductor or a transparent conductive film thereon, and as the chromium alloy, copper or silver is added to chromium in an amount of 0.1 to 100%. It relates to a semiconductor device in which 50% by weight is added and provided as an electrode.

"Prior Art" Conventionally, aluminum has been used as electrodes for semiconductor devices. However, although this aluminum is suitable for forming electrodes using a mask, it is inherently highly chemically reactive with oxidizing gases or silicon semiconductors, and is non-sublimable in maskless processes using laser processing methods. The material was inappropriate.

Further, for this reason, the inventor has proposed a method of using chromium as a material having laser processability. This chromium (purity of 99.9% or more) has excellent laser processability and has the advantage that no metal residue remains in the groove after laser scribing.

``Problem to be Solved by the Invention'' However, this metal chromium has a small reflection coefficient, resulting in what is called chromium. In addition, due to its high hardness, when it is formed on a semiconductor thin film or a transparent conductive film (CTF) and heat treated (200°C, 2 hours), minute cracks (observed with a metallurgical microscope from XIOQ to ×400) occur. A large number of these occur in the vicinity of the scribe or in the uneven step portions, and as a result, a peeling phenomenon occurs at the interface between the chromium film and the semiconductor.

For this reason, as a coating for an electrode, it is recommended to use a material that has a certain degree of softness and has adhesion to a semiconductor or a transparent conductive film. being admired. In addition, it is an important requirement for a conductive film to be subjected to laser processing that residual materials in the peripheral area where the laser beam is irradiated are not scattered and attached in the vicinity.

``Means for Solving the Invention J The present invention uses a chromium alloy to which copper or silver is added, that is, L':u-Cr alloy or Ag-Cr alloy, as a new material that eliminates many of the drawbacks of chromium alone. This is what I used.

Furthermore, the present invention provides this Cu--Cr alloy or heg-Cr alloy.
Copper or silver in the alloy was added in an amount of 0.1 to 50% by weight. Such a metal is applied to a semiconductor or a transparent conductive film 1 by a sputtering method, particularly a magnetron DC.
It was formed by sputtering to a uniform film thickness of 300 to 0.577.

``Function j'' The present invention is directed to applying such a chromium alloy to a non-single-crystal semiconductor to which hydrogen or a halogen element is added, or to a transparent conductive film made of tin or indium oxide or nitride, or a combination of chromium and silicon. Formed on a transparent conductive film of the alloy,
By using the electrode material, its sheet resistance is 5 Ω/mouth or less, generally 0.2 to 2 Ω/mouth (300 people to 0.5 μ
A material that has a thickness of 3000 Å or less), has excellent optical reflection properties, and is mechanically soft, that is, it does not apply mechanical stress to the underlying semiconductor material, etc. It was discovered as a material with excellent laser processability.

Example 1 Figure 1 shows Co-Cr (chromium-copper alloy) of the present invention, C
The reflectance of uAg (chromium-silver alloy) is compared with that of conventionally known chromium alone.

Figure 1 (^) shows chromium alone (50) on the surface of the insulating coating.
.

Added 2.5% by weight of copper (51), 50% by weight of copper
χ doped material (52) whose wavelength is 400 to 800n
It is shown in relation to the reflectance in the range of m.

Furthermore, in Fig. 1 (B), 1500 ml of ITO is deposited on a glass substrate.
It is formed to a human thickness, and then copper is added to it (so-called chromium alone) (53), 2.5% by weight is added (54), 50
χ doped (55) formed to a thickness of 1100 mm,
Regarding the wavelength range of 400 to B00nI11, the reflection from the glass surface side, that is, the irradiation light is reflected by the chromium alloy through ITO, and the reflection from the glass surface is investigated.

In any of these cases, it can be seen that when the chromium alloy of the present invention was used, the reflectance increased by 10% or more over a wide wavelength range. In particular, the improvement with short wavelength light of 400 to 600 nI11 is remarkable, and chromium alone, that is, blank.
It was found that the reflectance was significantly improved compared to chromium. This was also evident from visual observation, as the reflectivity changed from a deep black and white color to a so-called metallic silvery white color. The atomic radius of Cu and Ag is 10 compared to chromium.
The difference is only by %, so that alloys can be created in any amount. However, considering the direction of reflectance, it is necessary to add 0.1% by weight or more, and considering laser processability, it is practically recommended to add 50% by weight or less.
A weight % range was suitable. In addition, if 51% by weight or more of F is added, the physical properties of silver or copper, which have high thermal conductivity, will become strong during laser processing, so the pulse duration during laser processing should be 30 ns or less or the irradiation It was necessary to ensure processability by using an excimer laser to reduce the wavelength of light to 400 nm or less.In other words, when using the generally used wavelength of 0.5 to 1.1 μ, considering mass production, it was necessary to It was appropriate that the content be 50% by weight or less.

In the present invention, magnetron DC sputtering was used to form the Cu-Cr alloy and Ag-Cr alloy films. The conditions were to sputter with argon and perform high-speed evacuation using a cryopump to reduce the value of 1 to 3Ω70 to 1000 to 3Ω.
It was possible to obtain a sheet with a thickness of 1,300 ohms and a sheet resistance of 5 Ω/mouth or less as an electrode for a photoelectric conversion device. It is also possible to make these alloys by electron beam evaporation. However, in this method, only a sheet resistance of 10 to 20 ohms and a thickness of 1,500 to 2,000 ohms was obtained. Furthermore, it has been found that by using the alloy of the present invention, it is possible to produce an electrode material that is a chromium alloy that is soft enough to eliminate the occurrence of cracks, has a low sheet resistance, and has a high reflectance.

"Example 2" Details of a photoelectric conversion device using the present invention are shown below according to FIG. 2.

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

In the drawings, a substrate (1) having a light-transmitting property and an insulating surface, such as glass or a light-transmitting organic film, such as PES
Alternatively, PET was used. Here, the glass substrate is 10cm
X ] Ocn+ was used.

A light-transmitting conductive film having fluorine-doped tin oxide on two sides of this substrate was formed to a thickness of 500 to 3000 nm by known electron beam evaporation or sputtering.

After that, from the upper side of this substrate, a YAG laser processing machine (manufactured by NEC Corporation) is used to produce an average output of 0.3 to 3- (focal length: 40 mm).
The spot diameter is 20 to 1011φ, typically 4.
0μφ is controlled by a microcomputer and irradiates laser light from two directions, and by scanning it forms the first opening (13) for the scribe line, and the area between each element (3).
1), the first electrode (37) was produced in (11).

Open # (13) formed by laser scribing (LS)
) had a width of about 50 μm and a length of about 50 μm], and the depth was cut and separated so that there was no CTF residue in the open groove in order to complete the isolation between the first electrodes.

Thus the first element (31) and the second element (11)
The width of the area constituting the area is 5 to 40 mm, for example 8.3n+n
It was formed as +.

Thereafter, a non-single crystal semiconductor typically has a PN or PIN junction and is doped with a hydrogen or halogen element by plasma CVD, photo CVN or LPCVD. The crystalline semiconductor layer (3) is 0.3 to 1.0μ, typically 0.7μ.
It was formed to a thickness of .

A typical example is P type (SixC+-, O< x < l
) Semiconductor (approximately 300 people) - Type 1 amorphous or semi-amorphous silicon semiconductor (approximately 0.7μ) - Semiconductor with N-type microcrystals (grain size approximately 200 people) (approximately 500 people) One PIN junction or, from the substrate side, N-type microcrystalline silicon (approximately 300 people) semiconductor - ■ type semiconductor (approximately 0.7μ) - p-type mechanical crystallized Si semiconductor (approximately 200 people) - p-type Si, C,, -x (approximately 50 people
x-0,2~0.3) It is a semiconductor.

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

Furthermore, as shown in Figure 2 (R), the first lecture (1
3) over the left side (first element side) of the second opening (14). It was formed by step s.

The second open groove (14) thus exposed the side or side surface (8) and top surface (9) of the first electrode.

This second groove does not cut both ends of the semiconductor.
A portion of the semiconductor may be connected to each other in two regions as one or more openings.

As a result, a transparent conductive film (CTF) was formed on the side surface (8) (only the side surface or at the end of the side surface and the top surface) as shown in FIG. 2(C) as a part of the second electrode (38). Here I
TO (15) was formed by electron beam evaporation. Even if this ITO is connected with the connector (30), the contact resistance becomes an oxide-oxide contact (tin oxide-ITO contact) and no insulation barrier (insulator) is formed at the interface, so there is no contact during long-term use. There were no abnormalities such as an increase in resistance, which was preferable for practical use.

(10) In FIG. 2, as shown in FIG. 2(C), a second conductive film (25) is further formed on the CTF surface.
As shown in Example 1, a metal film (chromium alloy) containing 2.5% by weight of copper and containing chromium as a main component was prepared using the Macnetron sputtering method to give an average thickness of 1,100 people (sheet resistance: 1.4Ω/mouth). It was formed with.

After this, the third LS cuts and separates the plurality of second
(7) Electrodes (39) and (38) were isolated and formed using LS to obtain a third open groove (20).

This second conductive film (5) is a transparent conductive film (CTF) (
15) and the chromium alloy (25) of the present invention, or a monolayer of only the chromium alloy was used.

As this CTP, ITO (a mixture whose main components are indium oxide and tin oxide) (15) which makes good ohmic contact with the N-type semiconductor is formed to a thickness of 300 to 1500 mm. It was also effective to form this CTF on a P-type semiconductor with tin oxide as its main component. As a result, the second electrodes (15), (25
). As this CTF, a light-transmitting conductive film made of a non-oxide conductive film such as a chromium(II) moo silicon compound may be used.

This chromium metal is a metal film (25) of a chromium alloy to which 0.1 to 50% by weight of copper or silver is added.
It was formed to a thickness of 5 μm, typically 1000 to 1500 μm, by sputtering, particularly magnetron DC sputtering.

To form this third groove, the LS condition is a laser beam, for example, a Q-switched pulsed YAG laser with a wavelength of 1.06μ or 0.53μ (focal length 40mm, laser beam diameter 20-70μ, frequency 1-30KHz). Preferably 0
Pulsed light of ゜6μ or less (pulse duration 5 to 50
(n seconds).

Further, it is moved and scanned at an operating speed of 0.05 to 5 m/min, for example, 0.3 m/min, to create open grooves or holes in a dependent relationship with the previous process.

Furthermore, the depth of this third trench is such that, in a two-layer conductive film of CTF and chromium alloy, the non-single-crystal semiconductor is not simultaneously scribed and the semiconductor is not damaged in any way, and the depth is such that the upper surface or the very vicinity thereof (12) It was possible to form open grooves at depths up to (~200 people).

On the other hand, when forming a chromium alloy closely on the semiconductor without forming a CTF, this second
The isolation (20) is performed not only by selectively removing only the chromium metal of the semiconductor, but also by simultaneously removing the underlying semiconductor layer (3) and exposing a portion of the first electrode. did. (The drawing shows the case of an electrode made of CTF and chromium alloy.) In this case, the laser beam has a Gaussian distribution, has a sublimation property on the upper side when forming an open groove, and has a lower thermal conductivity than aluminum. In addition, a chromium alloy with oxidation resistance is added to the IT material with sublimation properties underneath.
This is presumed to be due to a mechanism that creates open grooves by simultaneously vaporizing and repelling O (silicon semiconductor in the case of a chromium alloy single-layer film).

In other words, by considering the processed surface as two layers, the second
The conductive film is isolated.

Thus, as shown in FIG. 2(C), a plurality of (13
) We were able to create a photoelectric conversion device in which the elements (31) and (11) were connected in series at the connecting part (4).

FIG. 2(D) shows an attempt to further complete the present invention as a photoelectric conversion device. That is, as a passivation film, a silicon nitride film (21) is uniformly formed to a thickness of 500 to 2,000 layers by plasma vapor phase method, charged phase method, or photo plasma vapor phase method, and the leakage current between each element is reduced. This further prevents occurrences due to adsorption of moisture, etc.

Further, an external lead terminal (23) was provided at the peripheral portion.

Thus, for the irradiation light (10), each element is
B. It is provided in a strip shape of 3mm x 94n+m, and furthermore, the inside of the connecting part is 150μm, the width of the external extraction electrode part is 3mm, and the peripheral part is 3mm, so that there are essentially 11 stages within 100mm x 100mm, and the effective area (8.3mm x 94mm)
11 stages of 85.8 cm'', that is, 8.6%).

As a result, the segment was 11.3% (1,05cm”)
, the board has a conversion efficiency of 9.4% (theoretically 10.3%, but due to the 11-stage series connection of resistors, the actual conversion efficiency has decreased (14). cm2)
), it was possible to have an output power of 8.3W.

Furthermore, this panel, for example, 40cm x 120cm
Or, package it by combining one or four pieces of 60cm x 20cm in series within a hard frame made of aluminum sash or a flexible frame made of carbon black.
It is possible to provide a 120 cm x 40 cm NEDO standard high power panel.

In addition, this NEDO standard panel panel uses Seaflex to attach the top surface of the photoelectric conversion device of the present invention to the back surface of the glass substrate (opposite the irradiation surface) to increase mechanical strength against wind pressure, rain, etc. It is also effective.

r effect j In the present invention, by using a chromium alloy in this way, it is possible to promote reflection of long wavelength light on the back electrode in a photoelectric conversion device, and as a result, the conversion efficiency of a semiconductor device, for example, a photoelectric conversion device can be improved. I was able to encourage improvement.

In addition, the thickness of the chromium alloy in such cases is from 300 to (15
) 3000 people In general, it is about 1000 people thin, so the electrode price is low, and its sheet resistance is 1 to 3 Ω/
Since it is an open circuit, it has the advantage that even if it is integrated, it does not substantially contribute to an increase in series resistance.

More importantly, in a high-temperature test at 150°C for 4000 hours, the heat-resistant components of the chromium alloy caused abnormal diffusion (migration) in the semiconductor, as seen in aluminum electrodes, causing short-circuit defects. There is no.

Many of these features can be taken as other features in addition to making the laser processing method.

In the present invention, copper is mainly shown as the chromium alloy. However, silver-chromium alloy also has the disadvantage that it is slightly more expensive to manufacture, but it has similar properties and is an alloy that simultaneously mixes copper and silver, and its atomic radius is 10% that of chromium.
A chromium alloy made by adding metal materials that differ only within the same range to soften its hardness and improve its reflective properties similarly had the sublimation property of laser light.

In the present invention, a photoelectric conversion device (16) is shown as a semiconductor device. However, it is also effective to use the electrode of the present invention in light emitting elements, photosensors, insulated gate field effect semiconductor devices, and the like.

In the present invention, the transparent conductive film is made of tin or indium.
It is composed of oxides of aluminum. However, it goes without saying that these may be provided as indium nitride (InN), tin nitride (SnJ4-), or indium tin nitride (InSNXN) by sputtering or plasma vapor deposition.

[Brief explanation of the drawing]

FIG. 1 shows the basic characteristics of light reflectance for the chromium alloy of the present invention. FIG. 2 is a longitudinal sectional view showing the manufacturing process of the photoelectric conversion device of the present invention. Patent Applicant Semiconductor Energy Research Institute, Inc. Representative Shun Hei Yamazaki (17) MiL ((PL+η) (A) Ryo-wo Ki) .,) Midori 1 (2) (8)

Claims (1)

[Scope of Claims] 1. A conductive film of a metal whose main component is chromium to which 0.1 to 50% by weight of copper or silver is added on the surface of a semiconductor, or a transparent conductive film on the semiconductor and the film. A semiconductor device comprising: a conductive film made of the metal described above. 2. A semiconductor device according to claim 1, wherein the semiconductor is made of a non-single crystal semiconductor whose main component is silicon to which hydrogen or a halogen element is added. 3. A semiconductor device according to claim 1, wherein the transparent conductive film is made of an oxide or nitride containing indium or tin as a main component. -! 4. The semiconductor device according to claim 1, wherein the transparent conductive film contains chromium silicide. 5. A semiconductor device according to claim 1, wherein the conductive film is provided as one electrode of a photoelectric conversion device.