JPH0695537B2 - Semiconductor device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure contact type semiconductor device, and more particularly to improvement of an electric contact structure between a semiconductor element and a conductor.

[Conventional technology]

In general, the electrical contact structure between the semiconductor element and the conductor in the pressure contact type semiconductor device employs a structure in which the two are mechanically pressure-welded without being welded to each other by a brazing material or the like. For this reason, it is characterized in that there is no risk of deterioration due to thermal fatigue of the brazing material.

However, on the other hand, in this type of pressure contact type semiconductor device, sufficient contact between the pressure contact surface between the semiconductor element and the conductor is maintained, the sliding property is improved, and the electrical and thermal resistance is increased. To ensure that these various conditions can be guaranteed at all times even during operation, and in particular to prevent excessive mechanical stress from being applied to the semiconductor element. A high degree of consideration is required.

Therefore, in the case of this type of pressure contact type semiconductor device,
For example, as shown in Japanese Examined Patent Publication No. 47-1818, a structure in which a cathode slide compensating plate is inserted is proposed.

FIG. 3 shows a pressure contact type semiconductor device, here a power thyristor, in which a conventional cathode slide compensation plate is inserted.
FIG. 4 shows an exploded cross section of the thyristor element and a part of the electric conductor which holds the thyristor element under pressure.

That is, in the conventional structure shown in FIG. 3, as is well known, the thyristor element 10 first diffuses gallium into the N-type silicon substrate 11 to obtain a PNP structure, and then one P A vertical PNPN structure is formed by diffusing phosphorus into the mold region to form an N-type region, and the surface on the side where phosphorus is not diffused and the molybdenum Mo disk 12 are alloy-bonded with an aluminum brazing material. Aluminum is vacuum-deposited on the other surface to form the cathode electrode 13 and the gate electrode.
14 is formed. Further, the cathode slide compensation plate 15 described above has a thermal expansion coefficient of the thyristor element.
Molybdenum Mo or Tungsten W close to 10 silicon
Are used.

However, in the case of the conventional power thyristor configured as described above, by supplying a current to the thyristor element 10, the power loss of the thyristor element 10 itself causes heat generation, the temperature rises, and the current is stopped. , It is cooled to the outside temperature by radiating heat to the outside. That is, a large temperature change occurs during operation. Copper is generally used for the cathode 16 and the anode 17 in terms of electrical conductivity, thermal resistance, and price. Copper has a coefficient of thermal expansion that is larger than that of silicon or Mo forming the thyristor element 10 by about one digit or more.

Here, if it is assumed that the cathode 16 using copper and the cathode electrode 13 of the thyristor element 10 are in direct contact, the difference between the thermal expansion coefficients of the two due to temperature fluctuations during operation described above. As a result, a large friction is generated on the mutual contact surfaces, the cathode electrode 13 made of aluminum is significantly damaged, and the stress on the silicon substrate 11 is also remarkable. In order to avoid such a difficulty, as shown in FIG. 3, a cathode sliding compensating plate made of Mo or W having an expansion coefficient close to that of silicon constituting the thyristor element 10.
A structure in which 15 is interposed between the cathode electrode 13 and the cathode 16 is used.

[Problems to be solved by the invention]

Although the conventional semiconductor device is configured as described above, the sliding between the cathode electrode 16 and the cathode slide compensating plate 15 is not sufficient, and as shown in FIG. 5, the semiconductor device is heated and cooled. By the thermal expansion of the cathode 16 due to the repetition of the above, the cathode slide compensating plate 15 undergoes lateral expansion and contraction, so that it is deformed beyond the deformation due to the expansion and contraction inherent in the cathode slide compensating plate 15. Therefore, the cathode electrode 13 in contact with the cathode slide compensating plate 15 is scraped by the cathode slide compensating plate 15, and as shown in FIG.
The cathode electrode 13 becomes thin due to repeated contraction, and finally the cathode slide compensation plate 15 becomes the silicon substrate 11 of the element 10.
There was a problem such as direct contact with the equipment and causing a failure of the device.

The present invention has been made in order to solve the above problems, and a semiconductor device having a longer life, which can prevent the cathode electrode from being scraped by the cathode slide compensating plate during repeated heating and cooling of the semiconductor device. Aim to get.

[Means for solving problems]

A semiconductor device according to the present invention includes a semiconductor element, and a cathode and an anode conductor which are pressed and held on the cathode side and the anode side of the semiconductor element to make electrical contact, wherein the semiconductor element and the cathode conductor are provided. And a soft metal plate sandwiched between them and at least two cathode slide compensation plates.

[Action]

According to the present invention, at least two cathode slide compensating plates having a soft metal plate sandwiched therebetween increase the sliding surface between the semiconductor element and the cathode conductor, so that the semiconductor can be repeatedly heated and cooled by the device. Prevents element scraping.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG.
In FIG. 1, reference numeral 15a is a cathode slide compensation plate newly added by the present invention, and 18 is a silver Ag plate inserted between the cathode slide compensation plates 15 and 15a.

In the present embodiment, the newly added cathode slide compensation plate 15a and silver plate 18 allow the semiconductor element 10 to be different from the conventional device.
The number of sliding surfaces between the cathode 16 and the cathode 16 increases by two. This allows
The amount of deformation of the cathode slide compensating plate 15, which is deformed by thermal expansion and contraction of the cathode 16 due to repeated heating and cooling of the device,
As shown in FIG. 2, the deformation amount is reduced as compared with the deformation amount in the conventional device shown in FIG. Therefore, the scraping of the cathode electrode 13 which has occurred conventionally is reduced, and the life of the semiconductor device is extended.

For example, in a heat cycle test with intermittent energization using a thyristor with a withstand voltage of 2500 V and an average current of 1000 A, the junction temperature
The device having a life of 30,000 cycles under the condition of 125 ° C. to 25 ° C. has a life of 100,000 cycles or more in the device according to the example of the present invention.

Since the present invention is effective by increasing the sliding surface between the semiconductor element 10 and the cathode 16, it is desirable that the surfaces of the cathode sliding compensation plates 15 and 15a be as smooth as possible, and the cathode 16 The surfaces of the cathode slide compensating plates 15 and 15a that are in contact with the Ag plate 18 and the Ag plate 18 are roll finished or # 4.
A 000 lap finish is desirable.

Further, in the above embodiment, the case where the silver Ag plate 18 is inserted has been shown, but a thin plate made of another soft metal such as copper Cu may be inserted.

Further, although the power thyristor has been described as an example in the above-described embodiment, the present invention may be applied to a transistor having a pressure contact structure, GTO, etc., and has the same effect as that of the above-described embodiment.

〔The invention's effect〕

As described above, according to the semiconductor device of the present invention, a semiconductor element and a cathode and an anode conductor that are held in pressure contact with the cathode side and the anode side of the semiconductor element to make electrical contact, Since the soft metal plate is provided between the semiconductor element and the cathode conductor and at least two cathode slide compensating plates are sandwiched between them, the sliding between the semiconductor element and the cathode conductor is ensured. As a result, the surface of the semiconductor device is increased, so that the cathode electrode is not scraped against the heat cycle of the semiconductor device, and the life and use period are extended.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a pressure contact portion of a semiconductor device according to an embodiment of the present invention, and FIG. 2 is a diagram for explaining a deformation amount of a cathode slide compensation plate of a semiconductor device according to an embodiment of the present invention. ,
FIG. 3 is a sectional view showing a conventional semiconductor device, FIG. 4 is a configuration diagram showing a pressure contact portion of the conventional semiconductor device, and FIG. 5 is a diagram for explaining scraping of a cathode electrode of the conventional semiconductor device. Is. 10 is a semiconductor element, 15 and 15a are cathode slide compensation plates, 16 is a cathode, 17 is an anode, and 18 is a silver plate. The same reference numerals in the drawings indicate the same or corresponding parts.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazuhiko Niwayama 4-1-1 Mizuhara, Itami City, Hyogo Prefecture Mitsubishi Electric Corporation Kita Itami Works (56) Reference JP-A-54-107264 (JP, A) JP-A-SHO 59-31034 (JP, A) Actual opening 50-120372 (JP, U) Actual opening 48-6957 (JP, U)

Claims (4)

[Claims] 1. A semiconductor device comprising: a semiconductor element; and a cathode and an anode conductor which are held in pressure contact with the cathode side and the anode side of the semiconductor element to make electrical contact with each other. A semiconductor device comprising at least two cathode slide compensation plates interposed between and having a soft metal plate sandwiched therebetween. 2. The semiconductor device according to claim 1, wherein the cathode slide compensation plate is made of molybdenum. 3. The semiconductor device according to claim 1, wherein the cathode slide compensating plate is made of tungsten. 4. The semiconductor device according to any one of claims 1 to 3, wherein the soft metal plate is made of silver.