JPH0478182B2 - - Google Patents

Description

[Detailed Description of the Invention] 1 [Field of Industrial Application] This invention relates to a pressure contact type semiconductor device,
More specifically, the present invention relates to an improvement in the electrical contact structure between a semiconductor element and a conductor in a pressure contact type semiconductor device.

[Conventional technology]

Generally, the electrical contact structure between the semiconductor element and the conductor in this type of pressure contact type semiconductor device is such that the two are not welded together using a brazing material or the like, but are mechanically pressed into contact with each other. As a result, there is no risk of deterioration of the brazing filler metal due to thermal fatigue.

On the other hand, in this type of pressure contact type semiconductor device, sufficient contact between the pressure contact surfaces between the semiconductor element and the conductor is maintained, and sliding properties are improved, as well as electrical and thermal In order to reduce the resistance and to ensure that these conditions are always met even during operation, it is necessary to ensure that excessive mechanical stress is not applied, especially to semiconductor elements. Advanced technical considerations are required.

Therefore, in the case of this type of pressurized contact type semiconductor device, in order to meet such requirements, a cathode sliding compensator plate is used, as shown in Japanese Patent Publication No. 47-4818, for example. Structures involving intervention and insertion have been proposed.

FIG. 2 shows a conventional pressure contact type semiconductor device in which such a cathode sliding compensation plate is interposed and inserted;
Here, a power thyristor is shown, and the thyristor element and a part of the conductor holding the thyristor element in pressure contact with each other are shown in an exploded cross section.

That is, in the conventional configuration shown in FIG. 2, the thyristor element 10 is constructed by first diffusing gallium into an N-type silicon substrate 11 to obtain a PNP configuration, and then, as is well known,
By diffusing phosphorus into one P-type region to form an N-type region, a vertical PNPN structure is created, and the surface on which phosphorus is not diffused and the molybdenum disk 12 are alloyed with aluminum brazing material. join,
On the other surface, aluminum is vacuum-deposited to form a cathode aluminum-deposited layer 13 and a gate aluminum-deposited layer 14.

Moreover, as the cathode sliding compensation plate 15 described above,
Molybdenum, tungsten, etc., whose coefficient of thermal expansion is close to that of the silicon of the thyristor element 10, are used, and in order to obtain good sliding properties, the surface is polished to remove irregularities, and the roughness of the surface is reduced to 0.5μ or less. It has been processed.

Further, 16 and 17 are each made of a conductive material made of a soft metal such as silver, in order to compensate for incomplete contact caused by distortion of the thyristor element 10 when the thyristor element 10 is pressed and held. It is a sexual insertion board, and furthermore, 18,1
In order to make electrical contact with the cathode and anode of the thyristor element 10, a cathode conductor and an anode conductor each made of a metal with good electrical conductivity such as copper are brought into pressure contact with the cathode and anode of the thyristor element 10. It is the body.

Here, each of the above-mentioned members is arranged in the order shown in FIG. 2, that is, the cathode sliding compensation plate 15 is placed on the cathode side of the thyristor element 10, and the insertion plates 16 and 17 are placed on both the cathode and anode sides, respectively. They are stacked on top of each other and held under pressure by a cathode conductor 18 and an anode conductor 19, and assembled as shown in FIG. 3 to be used as a power thyristor.

However, in the case of a conventional power thyristor configured in this way, when current flows through the thyristor element 10, heat is generated due to its own power loss, the temperature rises, and the current is stopped. As a result, it is cooled down to the outside temperature by heat radiation to the outside, that is, it is subject to large temperature fluctuations during operation. In this power thyristor, as described above, the conductive parts holding the thyristor element 10 in pressure contact include silicon, molybdenum, tungsten, etc., which have a coefficient of thermal expansion close to that of silicon, as well as materials with a coefficient of thermal expansion of 1.
They use materials such as silver and copper that are orders of magnitude larger.

Now, if we were to create a cathode conductor using copper,
Assuming that the cathode surface of the thyristor element is in direct contact with the cathode surface of the thyristor element, the difference in the coefficient of thermal expansion between the two due to the above-mentioned temperature change will cause large friction at the mutual contact surface, causing the thyristor element to The cathode aluminum deposited layer of is severely damaged,
In addition, the stress on the silicon substrate becomes significant.In order to avoid such structural difficulties, molybdenum, which has a coefficient of thermal expansion similar to that of the silicon of the thyristor element, is used as the cathode sliding compensator.
A metal plate such as tungsten is inserted between the thyristor element and the cathode conductor to facilitate sliding between the two and reduce friction against the thyristor element.
For this purpose, both sliding surfaces of the cathode sliding compensation plate are polished as described above.

[Problem that the invention seeks to solve]

However, the power thyristor structure according to the conventional example has the following problems.

In other words, since aluminum is a metal that is very easily oxidized, an extremely thin aluminum oxide film is formed on the surface of the cathode aluminum vapor deposited layer of the thyristor element. It is interposed between the cathode sliding compensation plate, which should be in good electrical contact with the cathode aluminum vapor deposited layer, and the electrical contact between the two is insufficient, causing a potential drop. This increases the power loss inside the thyristor element, which adversely affects the thyristor characteristics.

This invention was made to solve these conventional problems, and its purpose is to improve the electrical contact between the semiconductor element and the cathode sliding compensator, and to improve the electrical contact between the semiconductor element and the cathode conductor. An object of the present invention is to provide a semiconductor device of this type, which can effectively maintain sliding properties between the cathode sliding compensator and the cathode sliding compensator.

[Means for solving problems]

In order to achieve the above object, a semiconductor device according to the present invention has a cathode sliding compensation plate in which the side facing the cathode conductor has a smooth surface and the side facing the semiconductor element has an uneven surface. be.

[Effect]

That is, in this invention, by making the side of the cathode sliding compensation plate facing the cathode conductor a smooth surface,
As in the past, effective sliding properties between the two can be maintained, and by making the side facing the semiconductor element an uneven surface, the aluminum oxide film that forms on the surface of the cathode aluminum vapor deposited layer of the semiconductor element can be broken. As a result, good electrical contact can be obtained between the two.

〔Example〕

Hereinafter, one embodiment of a semiconductor device according to the present invention will be described in detail with reference to FIGS. 1a and 1b.

FIGS. 1a and 1b are cross-sectional views showing, in the order of assembly, the main parts of a semiconductor device to which this embodiment is applied. In the configuration of the embodiment in FIG. or a considerable portion thereof.

In this embodiment device, as shown in FIG. 1a, the side of the cathode sliding compensation plate 15 made of molybdenum, tungsten, etc., which faces the cathode conductor 18, is arranged in the same manner as in the conventional case. For example, by polishing using an abrasive with a small particle size, the surface roughness is finished to a smooth surface 15a of 0.5μ or less, and the semiconductor element using silicon, in this case, the thyristor element, is polished. The side facing 10 is treated with, for example, nitric acid or a mixture thereof, or polished using an abrasive with a large particle size to form an uneven surface 15b with a surface roughness of about 1 to 5 μm. It is finished so that it becomes.

Furthermore, on the surface of the cathode aluminum vapor deposited layer 13 in the thyristor element 10, an aluminum oxide film 13 naturally formed after the vapor deposition.
a is formed.

Therefore, when the semiconductor device according to the configuration of this embodiment is assembled, as shown in FIG. The oxide film 13a is embedded and pressed, and when the oxide film 13a is torn, the thyristor element 10 and the cathode sliding compensator plate 15 come into direct contact with each other, and in this case, a good electrical connection between the two is achieved. You can get targeted contact.

In this state, even if the sliding property between the two is deteriorated due to the uneven surface 15b, the coefficient of thermal expansion of the two is approximately equal, so friction caused by temperature changes during device operation will not be a particular problem. However, it is almost negligible.

Further, the other smooth surface 15a of the cathode sliding compensation plate 15
As in the case of the conventional example, since effective sliding properties are maintained, there is no risk that expansion and contraction of the cathode conductor 18 due to temperature changes will affect the thyristor element 10.

〔Effect of the invention〕

As detailed above, according to this invention,
A semiconductor element having a metal layer on the cathode side and a metal oxide film formed on the metal layer, cathode and anode conductors that are held in contact pressure on the cathode and anode sides to make electrical contact, and these In a semiconductor device comprising a semiconductor element and a cathode sliding compensator interposed between a cathode conductor, the cathode sliding compensator plate has a smooth surface on the side facing the cathode conductor and a rough surface on the side facing the semiconductor element. Since the cathode sliding compensator plate is formed on each side, it is possible to obtain good electrical contact with the semiconductor element, and at the same time maintain effective sliding properties with respect to the cathode conductor, ensuring sufficient power loss within the semiconductor element. It has the advantage that the characteristics of this type of semiconductor device can be improved.

[Brief explanation of the drawing]

FIGS. 1a and 1b are cross-sectional views showing the main structure of a semiconductor device according to an embodiment of the present invention in the order of assembly, and FIG. FIG. 3 is a cross-sectional view of the structure assembled into a thyristor. 10... Thyristor element, 11... N-type silicon substrate, 12... Molybdenum disk, 13...
... Cathode aluminum vapor deposition layer, 13a ... Aluminum oxide film, 14 ... Gate aluminum vapor deposition layer, 15 ... Cathode sliding compensation plate, 15a ... Smooth surface,
15b... Uneven surface, 16, 17... Insertion plate, 18
and 19... cathode and anode conductor.

Claims (1)

[Claims] 1. A semiconductor element having a metal layer on the cathode side and a metal oxide film formed on the metal layer, and a semiconductor element that is held in contact with the cathode side and the anode side of the semiconductor element to make electrical contact. a cathode conductor and an anode conductor, and a cathode sliding compensation plate interposed between these semiconductor elements and the cathode conductor; A semiconductor device characterized in that a side facing the semiconductor element is formed as a smooth surface, and a side facing the semiconductor element is formed as an uneven surface. 2. The cathode sliding compensation plate is formed so that the surface on the cathode conductor side has a surface roughness of 0.5μ or less, and the surface on the semiconductor element side has a roughness of 1 to 5μ. The semiconductor device according to scope 1.