JPS62291122A - Semiconductor device - Google Patents

Abstract

PURPOSE:To improve the working efficiency by fusionbonding thermal stress buffer plates to electrodes to be integrated to prevent the plates from being displaced, and reducing the number of components to be assembled as a semiconductor device. CONSTITUTION:Thermal stress buffer plates 2a, 3a interposed between a semiconductor element 1 and the anode and cathode electrodes 4, 5 are respectively integrated with the electrodes 4, 5 by brazing or simultaneous rolling, and used as anode and cathode electrode assemblies 4A, 5A. Thus, the electrode assemblies in which the plates are integrated are used to prevent the plates from being displaced with respect to the element 1, thereby always applying a uniform pressurizing stress to the element 1. Since the plates 2a, 3a having similar thermal expansion coefficient to that of the element 1 are contacted with the element 1, a thermal stress applied to the element 1 can be reduced.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a semiconductor device with a press-contact structure, and in particular to an electrode structure suitable for relieving thermal stress applied to a semiconductor element. The present invention relates to a semiconductor device having:

(Prior Art) In general, the addition of negative and positive electrodes in a semiconductor device includes: 1.
Copper, which is a durable conductor, is used. The coefficient of thermal expansion of copper is about 3 to 4 times that of a semiconductor element made of an additive such as silicon.

Therefore, when holding a semiconductor element and pressing an electrode, thermal stress caused by the difference in thermal expansion coefficient between the electrode and the semiconductor element is applied to the semiconductor element, and in severe cases, it may lead to destruction of the semiconductor element. be.

Therefore, in order to alleviate this thermal stress, a thermal stress relief plate made of a metal such as tungsten or molybdenum, which has a thermal expansion coefficient similar to that of the semiconductor element, is installed between the electrode and the semiconductor element. inserted in between.

In a semiconductor device having such a press-contact structure, a structure in which, for example, an F'5-Ni alloy plate is used as the thermal stress buffer plate is shown in Japanese Utility Model Application Laid-Open No. 56-84347.

FIG. 2 is a sectional view of a press-contact type semiconductor device constructed according to the prior art disclosed in, for example, Japanese Utility Model Application Publication No. 56-84347.

As shown in FIG. 2, the semiconductor device 1 generally has the following characteristics:
They are brought into pressure contact and held by the anode electrode 4 and the cathode electrode 5 via the anode side thermal stress buffer plate 2 and the cathode side thermal stress buffer plate 3, respectively.

Note that 8 covers the peripheral edge of the semiconductor element 10 that has been subjected to the passivation treatment 8 to mechanically, electrically and electrically maintain it, and also functions to position the semiconductor element 1 with respect to the insulating cylinder 6. It is an annular rubber member.

As described above, in the prior art, thermal stress relief plate 2. (
Alternatively, 3) is inserted between the electrode 4 (or 5) and the semiconductor element 1, so that the thermal stress buffer plate 2 (or 3) is held or fixed in order to prevent it from being positioned relative to the semiconductor element 1. The method and structure for doing so must be considered.

As a method for fixing the thermal stress buffer plate 2 (or 3), in the conventional device shown in FIG. A structure is adopted in which the two are fitted together.

A similar electrode/thermal stress buffer plate fixing structure is disclosed in JP-A-54-3.
It is also described in Publication No. 7681.

(Problems to be Solved by the Invention) As mentioned above, when applying the conventional technology, a means for holding or fixing the thermal stress buffer plate inserted between the electrode and the semiconductor element must be provided. It won't happen.

Without such a means, the thermal stress buffering plate would move freely between the electrode and the semiconductor element, and the contact area (area) of the thermal stress buffering plate in contact with the semiconductor element would become uneven. . That is, the relative position of the thermal stress relief plate to the electrode and the semiconductor element is 15 degrees.

In this way, when a semiconductor device is pressed and clamped with the thermal stress buffer plate misaligned, uneven stress is applied to the semiconductor element via the thermal buffer plate that is misaligned with respect to the semiconductor element, and in severe cases, However, there was a problem in that the semiconductor element was destroyed.

Furthermore, there is also the disadvantage that the number of parts increases when assembling a semiconductor device, resulting in poor work efficiency.

On the other hand, as another method for preventing the relative position f#L of the m stress buffer plate, there is a method of alloy bonding the thermal stress buffer plate to the semiconductor element through a suitable brazing material.

In particular, on the anode side of the semiconductor element itself, it is known to bond a thermal stress buffer plate to the semiconductor element with an alloy for the purpose of alleviating thermal stress applied to the semiconductor element and reinforcing the semiconductor element.

However, when such an alloy adhesive structure is applied to the cathode side of a semiconductor element, the following problems occur.

That is, except for diodes that do not have a unique electrode structure (pattern) on the cathode side, semiconductor devices such as general reverse blocking thyristors, reverse conduction thyristors, optical direct ignition thyristors, and GTO (gate turn-off) thyristors, The cathode side has a unique electrode structure (gate pattern) to maintain the characteristics of each element, and when the thermal stress buffer plate is alloy-bonded to the cathode side of the semiconductor element, the characteristics of the element are The problem is that it is possible to lose.

An object of the present invention is to prevent the position t'1r4- of the thermal stress buffer plate by fusing and integrating the thermal stress buffer plate not with the semiconductor element but with the electrode, and to provide a component for assembling a semiconductor device. The goal is to reduce the number of points and increase work efficiency.

(Means for Solving the Problem) The above thermal stress buffer plate is inserted between the electrode and the semiconductor element without using a special structure for holding or fixing the thermal stress buffer plate. The above object of preventing relative positional deviation between the semiconductor element and the semiconductor element is achieved by integrating the thermal stress buffer plate with the electrode.

(Function) The above-mentioned thermal stress buffer plate is bonded and fixed to an electrode, and this is assembled as a new electrode into a semiconductor device having a press-contact structure.

Therefore, there is no need to insert a thermal stress buffer plate between the electrode and the semiconductor element, and abnormal non-uniform stress is not applied to the semiconductor element due to relative positional deviation of the thermal stress buffer plate.

On the other hand, since a thermal stress buffer plate having a thermal expansion coefficient similar to that of the semiconductor element is used as part of the electrode material, the semiconductor wire is There will be no need for children to be destroyed.

Furthermore, since the thermal stress buffer plate and the electrode are integrated, the number of parts to assemble the semiconductor device is reduced, and there is no need to align the thermal stress buffer plate, which greatly improves the efficiency of assembly work. improves.

(Example) FIG. 1 shows a structural cross section of an example of the present invention in which an electrode and a thermal stress buffer plate are integrated. The symbols used in FIG. 1 are the same as or equivalent to those shown in FIG. 2.

In this embodiment, the semiconductor cord 1 and the anode and cathode electrodes 4,
Thermal stress buffer plates 2a and 3a, which are interposed between the anode and cathode electrodes 4 and 5, are integrated with the anode and cathode electrodes 4 and 5, respectively, using a wax coating or simultaneous rolling method, and these are assembled into an anode and cathode electrode assembly, respectively. 3D 4A.

Used as 5A.

By using the electrode assembly that integrates the thermal stress buffer plate in this way, the thermal stress buffer plate can be attached to the semiconductor element 1 without having to have a structure in which the thermal stress buffer plate is fixed to the semiconductor element with (-). It is possible to prevent the occurrence of positional shift and to apply uniform pressure stress to the semiconductor cord 1 at all times.

On the other hand, since the thermal stress buffer plate 2a (or 3 m) having a coefficient of thermal expansion similar to that of the semiconductor cord 1 is brought into contact with the semiconductor cord 1, it is possible to reduce the thermal stress applied to the semiconductor cord IK. can.

Furthermore, since these thermal stress buffer plates and electrodes are integrated into an electrode assembly, the number of assembled parts of the semiconductor device is reduced, and there is no need to position the thermal stress buffer plates, improving assembly work efficiency. will improve.

In the embodiment shown in FIG. 1, the thermal stress buffer plate 2a.

In addition to 3a, a thermal stress buffer plate made of the same material and having the same dimensions is also integrated on the surface opposite to the electrodes 4 and 50 (the surface opposite to the semiconductor cable 1), forming a so-called sandwich structure.

This prevents bending of the electrode assembly due to the bimetallic effect based on the difference in thermal expansion coefficient between the electrodes 4 and 5 when the thermal stress relief plate is fixed and integrated only on one side of the electrodes 4 and 5. This is to prevent this.

The curvature of the electrode assembly due to the bimetallic effect can be achieved by adjusting the thickness of each electrode and thermal stress buffer plate appropriately based on the ratio of their longitudinal elastic modulus and thermal expansion coefficient, in addition to the sandwich structure shown in the figure. It can also be prevented by

As a method of integrating the thermal stress buffer plate with the electrode, it is possible to bond the two together using a suitable brazing material, or to form a so-called clad material by simultaneous rolling.

Although the above-mentioned embodiment describes the case of a diode having a double-sided electrode press-contact structure, the present invention is a thyristor (depression blocking thyristor) having an electrode structure on the cathode side.

Needless to say, it is particularly useful for reverse conduction thyristors, optical direct ignition thyristors, GTO thyristors, etc.).

Furthermore, it goes without saying that the present invention can be applied to the case where the semiconductor element 1 is alloy-bonded to a thermal stress buffer plate on the anode side.

(Effects of the Invention) The present invention integrates a thermal stress buffer plate inserted between an electrode and a semiconductor element of a press-contact type semiconductor device on the electrode side to form an electrode assembly. Since there is no misalignment with respect to the element, there is an effect that the stress applied to the semiconductor element can be made uniform.

Further, since the thermal stress buffer plate is interposed between the electrode and the semiconductor element, it is natural that it has the effect of reducing the thermal stress applied to the semiconductor element. Furthermore, by integrating these, the number of assembled parts is reduced, work efficiency is improved, and a relatively inexpensive semiconductor device can be provided7).

[Brief explanation of the drawing]

FIG. 1 is a structural sectional view of one embodiment of a pressure contact type semiconductor device according to the present invention, and FIG. 2 is a structural sectional view of a pressure contact type semiconductor device using a conventional technique.

Claims (3)

[Claims] (1) including at least two opposite conductivity type semiconductor regions;
a semiconductor element having a predetermined structure; a pair of electrodes that press and hold the semiconductor element; and a pair of electrodes having a thermal expansion coefficient similar to that of the semiconductor element, and an intervening device between each of the electrodes and the semiconductor element. In the semiconductor device, the semiconductor device is configured of a thermal stress buffer plate and an envelope made of an insulating cylinder that supports the pair of electrodes and electrically insulates them, at least one of the thermal stress buffer plates is A pressure contact type semiconductor device, characterized in that it is fixedly integrated with adjacent electrodes to form an electrode assembly. (2) The semiconductor device according to claim 1, wherein the electrode assembly is a clad material obtained by co-rolling the electrode material and the same material as the thermal stress buffer plate. (3) In the electrode assembly, the electrode is made of the same material as the thermal stress buffer plate.
The semiconductor device according to claim 1 or 2, characterized in that it has a structure sandwiched between plates of the same size.