JPH03290965A - Semiconductor device - Google Patents

Abstract

PURPOSE:To make uniform the pressure contact of the opposite sides of an element formed of a support plate and a semiconductor substrate fixed together, with an electrode body, by providing the electrode body constructed of an inside columnar part and an outside columnar part being different in the outside diameter, and a spring member pressing the outer peripheral part of the support plate. CONSTITUTION:The section of an anode copper electrode body 7 has a projecting shape formed of two columnar parts joined to each other and having different diameters, and the body comes into contact with an Mo support plate 3 on the side of the end face 71 of the part having a smaller outside diameter, while a ring-shaped spring 9 is disposed in a space existing between the plate and the columnar body having a larger cross sectional area. When a prescribed pressure is applied by the spring 9 to the outer peripheral part of the support plate 3, the warp of an element constructed of an Si substrate 1 and the support plate 3 is corrected and a number of cathode electrodes 2 come into contact with an Mo contact plate 8, and the support plate 3 with the end face 71, on an entire plane even when no external pressure is applied. Accordingly, the pressure contact of a cathode copper electrode body 6 with the electrodes 2 through the intermediary of the contact plate 8 and the pressure contact of the electrode body 7 with the support plate 3 at the time when a pressure is applied from outside become uniform, and electric connection with all the electrodes 2 is made uniformly. Thus, the breaking current characteristic of a gate turn-off thyristor can be improved.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention is characterized in that a supporting plate made of a material having a coefficient of thermal expansion close to that of the semiconductor material is fixed to one surface of a semiconductor substrate, and The present invention relates to a semiconductor device in which electrode bodies are brought into direct or indirect pressure contact with one surface of a support plate by an external force.

[Conventional technology]

Diode, thyristor, gate turn-off (GTO)
In power semiconductor devices such as Cyrisk, when storing a semiconductor substrate in a container that has a part made of a material such as copper, which is a good conductor of electricity and heat, it is necessary to It is well known that a pressure contact structure is used in which an electrode body made of copper or the like, which forms part of the container, is brought into contact with the semiconductor substrate by external force in order to prevent the stress caused by the difference from being applied to the semiconductor substrate. .

However, since semiconductor substrates are easily damaged during handling, the semiconductor substrate made of, for example, silicon is alloyed and bonded with a support plate made of a material with a coefficient of thermal expansion close to that of silicon, such as molybdenum or tungsten, to form an element. It is usually done.

FIG. 2 shows a conventional GTO Sirisk, in which a Si substrate 1 with a cathode electrode 2 provided on the negative side is fixed on a Mo support plate 3 by alloying with M, and a ceramic outer cylinder 4 and The cathode electrode body 6 and the seven-node copper electrode body 7 are housed in a container which is airtightly connected to the cathode electrode body 6 through a flexible portion 5. Due to pressure from outside the container, the cathode copper electrode body 6 is brought into pressure contact with the cathode electrode 2 via the contact plate 8 made of Mo, and the anode copper electrode body 7 is brought into pressure contact with the support plate 3.

[Problem to be solved by the invention]

However, for example, the thermal expansion coefficients of Si and Me are not completely equal, so when the 33 substrate 1 with a thickness of 0.65 mm and the Mo support plate 3 with a thickness of 2 mm are bonded with an alloy cathode, the resulting element has the shape shown in the figure. Warpage occurs in which the Mo side becomes a concave surface. This tendency becomes more pronounced as the area of the element becomes larger; for example, in an element with a diameter of 60 m, a warp of about 0.1 length occurs. The state of such warpage differs from element to element, and even if a force of up to 3 tons is applied between the electrode bodies 6 and 7 on both sides of an element with warpage, the pressure between the element and the electrode body will not be reduced. It is difficult to make it uniform.

In particular, the cathode electrode 2 on one side of the Si substrate, such as GTO Sirisk, has a diameter of 1,000 to 20,000
In an element that is subdivided into 00 pieces, uneven pressure will cause poor electrical contact between some of the cathode bridges on the niremet and the contact plate 8, resulting in a decline in the performance of the semiconductor device. There was a problem.

An object of the present invention is to provide a semiconductor device in which both sides of an element to which a support plate and a semiconductor substrate are fixed are brought into uniform pressure contact with an electrode body.

[Means to solve the problem]

In order to achieve the above object, the present invention provides that one side of a semiconductor substrate is fixed on a support plate made of a material having a coefficient of thermal expansion similar to that of the semiconductor material, and an electrode body made of a highly conductive material and the semiconductor substrate are bonded to each other. In a semiconductor device in which the electrical connection with the other surface and the support plate is made by pressure contact using external pressure, one! The scraping body consists of an inner columnar part having an outer diameter smaller than the outer diameter of the support plate and whose end surface is in contact with the support plate, and an outer columnar part having an outer diameter larger than that columnar part, and is formed inside the outer columnar part. A spring member is provided between the step surface and the support plate surface to press the outer circumference of the support plate.

[Effect]

By applying pressure to the outer periphery of the support plate by the spring member, warpage is corrected by fixation between the support plate and the semiconductor substrate, and even when no external pressure is applied, both types of scrapers and the semiconductor substrate surface or the support plate surface are Since direct or indirect contact is made over the entire surface, uniform pressurized contact is achieved by external pressure.

〔Example〕

FIG. 1 shows a GTO thyristor according to an embodiment of the present invention,
Components common to those in FIG. 2 are given the same reference numerals. In this GTO thyristor, the anode copper electrode body 7 has a convex cross section in which two columnar parts with different diameters are connected, and contacts the Mo support plate 3 of the element with a diameter of 67n on the end face 71 side having a small outer diameter.

The width that exists between the Mo support plate 3 around the columnar part of the anode copper electrode body 7 with an outer diameter of 50 m and a small cross-sectional area and the columnar part of the anode copper electrode body 7 with an outer diameter of 65 m and a large cross-sectional area. 7
．． An annular spring 9 is arranged in the space of 5, and this spring 9 applies a pressure of about 100 mm to the outer circumference of the Mo support plate 3. Due to this pressure, the warpage of the element consisting of the Si substrate 1 and the Mo support plate 3 is corrected. The entire surface is in contact even when no pressure is applied. Therefore, when external pressure is applied, the cathode copper electrode body 6 is brought into pressure contact with the cathode electrode 2 via the contact plate 8, and the anode copper electrode body 7 is
.

Pressure contact with the support plate 3 is made uniform. Therefore, uniform electrical connections are made to all of the large number of cathode electrodes.

Although the above embodiments have been described with respect to a GTO thyristor, they can also be applied to other power semiconductor devices having a pressure contact structure, such as diodes, ordinary thyristors, and reverse conduction thyristors. Further, the present invention can also be applied to a semiconductor device that does not use the Mo contact plate 8 or a semiconductor device that uses a movable intermediate plate made of silver or the like instead.

〔Effect of the invention〕

According to the present invention, when a semiconductor substrate is mounted on a support plate, the warpage caused by the difference in coefficient of thermal expansion is corrected by applying pressure to the outer periphery of the support plate with a spring material. The contact plates can be brought into contact in a two-dimensional manner. As a result, when applying pressure to the picture electrode body, it is possible to make a uniform electrical connection over the entire surface of the element with the electrode or supporting plate, eliminating the problem of current imbalance due to uneven contact. An improvement in the breaking current characteristics was achieved.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a GTO thyristor according to an embodiment of the present invention, and FIG. 2 is a sectional view of a conventional GTO thyristor. 1: Silicon substrate, 2: Cathode electrode, 3: MO support plate, 6: Cathode copper Ti body, 7: Anode electrode body, 8:
Mo contact plate, 9: annular spring. Figure 1 Figure 2

Claims (1)

[Claims] 1) One surface of the semiconductor substrate is fixed on a support plate made of a material with a thermal expansion coefficient similar to that of the semiconductor material, and an electrode body made of a highly conductive material is connected to the other surface of the semiconductor substrate and the support plate, respectively. In the case where the electrical connection is made by pressurized contact by external pressure, one electrode body has an outer diameter smaller than the outer diameter of the support plate, and an inner columnar part whose end surface is in contact with the support plate, and the columnar part. What is claimed is: 1. A semiconductor device comprising: an outer columnar portion having a larger outer diameter, and comprising a spring member for pressurizing the outer peripheral portion of the support plate between a step surface formed inside the outer columnar portion and the support plate surface.