JPS61134068A - Semiconductor device - Google Patents

Abstract

PURPOSE:To enable to make uniform contacts also with electrodes arranged in the periphery of the element surface at the time of putting a contact electrode body in pressure contact with a semioconductor element having a spherical curve, by a method wherein the electrode arranged in the periphery is made thicker than the electrode arranged at the center. CONSTITUTION:The Si substrate 1 is brazed to a molybdenum plate 2 with Al, and the difference between the central rising part of such a reverse conduction thyristor element 10 and its periphery is about 80mum. Before evaporation of an Al electrode on the top of this thyristor element, a thyristor electrode 31 located at the center is made 30mum thick, and a diode electrode 32 provided in the periphery 60mum thick. Keeping a 30mum thickness between the center and the periphery like this and clamping the element under a force of 2 tons by sandwiching it between electrode bodies 4, 5 reduce the element curve to some degree and make both electrodes 31, 32 contact the upper electrode body 4. It is necessary to choose the difference in thickness between both electrodes 31, 32 in a suitable size according to the curve of the element 10, diameter and clamping pressure, etc. Evaporation of both of the electrodes discretely to a desired thickness can be easily performed.

Description

[Detailed description of the invention] [Technical field to which the invention pertains] The present invention provides a semiconductor device in which electrodes on both sides of a semiconductor substrate are provided with metal electrodes at the center and periphery of the top surface, and a support plate serving as one electrode is brazed to the bottom surface of the semiconductor substrate, and the electrodes are brought into pressure contact with a contact electrode body. Regarding. [Prior art and its problems]

Figure 2 schematically shows the electrode connection method of a conventional flat semiconductor device for power use.The lower surface of a silicon substrate l is made of molybdenum, tungsten, etc., which has a coefficient of thermal expansion relatively similar to that of silicon, and serves as reinforcement. The support [2 is fixed using aluminum or the like as a brazing material. An aluminum electrode 3 is formed on the upper surface of the base 1 to a uniform thickness by a method such as vapor deposition, and the semiconductor element 10 in which the silicon vi 1 and the support 2 are integrated is placed between upper and lower parts made of, for example, a wire block. It is sandwiched between the contact electrode bodies 4.5 and pressed into contact with each other at a pressure of 1 to 100 ton. However, silicon and support @z, electric value 3
Since the material has a large thermal expansion coefficient, the semiconductor element 10 is always curved into a large spherical shape as shown in FIG. Therefore, even if both electrode bodies 4.5 are tightened with force, the electrode bodies do not come into uniform contact with the support It2 or the upper electric bridge 3, and the electrode bodies are unstable, especially at the periphery of the element. This is particularly a problem in the case of a reverse conduction cyrisk, in which a diode is integrated around the thyrisk in antiparallel to the thyrisk. In fact, in a reverse conduction thyristor with a diameter of 70 mm and a silicon wafer with a thickness of 400 μm and a molybdenum plate with a thickness of 3 μm as a support plate, the semiconductor element was bent by about 80 μm, and the contact electrode body caused a bend of 3 tons. Even when pressurized with force, the electrodes of the diode part installed in the width of the three peripheral fins made contact [they did not make uniform contact with the rod, and more than a forward voltage drop was observed, causing local destruction in this part. happen.

[Object of the Invention] The present invention eliminates the above-mentioned drawbacks and makes it possible to pressurize contact electrode bodies with respect to semiconductor elements having a spherical bend. Even if the contact is uniform (
1 semiconductor device that can be tested! The purpose is to provide [Summary of the Invention] In the semiconductor device according to the present invention, by making the thickness of the electric bridges arranged at the periphery thicker than the thickness of the electrodes arranged at the center, uniform contact is made with the peripheral electrodes at the same time as with the center electrode. will be held. DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic shearing diagram of a reverse cut-through tilter according to an embodiment of the present invention. Silicon base 4 ftl is A1 on molybdenum temporary 2 with thickness 4 (t. μm, diameter 70 mackerel, thickness of 3 trout)
It is brazed by. The difference between the central raised part and the peripheral part of the reverse conduction thyristor element 10 is approximately 80 microns. A on the top surface of this Sirisk element.
When depositing the 11i pole, the electrode 31 of the thyristor located at the center is set to have a depth of 30 μ-, and the electrode 32 of the diode provided around the periphery with a width of 3 cranes is set to have a thickness of 60 μ-. If a thickness of 30 μm is provided between the central part and the peripheral part in this way, and the electrode bodies are sandwiched between 4°5 and tightened with a force of 2 tons, the curvature of the element will be somewhat reduced, and both sides will be Electrode 31
．． 32 contacts the upper electrode body 4. The difference in thickness between the two electrodes 31 and 32 requires selecting an appropriate size depending on the bending, diameter, and pressure of the element 10. Both electrodes can be easily deposited separately to the desired thickness. Can be done. Effects of the Invention According to the present invention, among the electrodes on the upper surface of the semiconductor element which are high in the center and have a spherical bend,
In a WIJIL way to increase the thickness of tffl, R'[
Sufficiently uniform contact can be obtained even with the electrode on one side, so it is impossible to increase the pressure when hammering or tightening to a size that would cause damage to the semiconductor substrate. In such a case, uniform pressure tI can be applied to the ilEl bipoles in the central and peripheral areas without changing the material of the support plate. Therefore, it can be particularly effectively applied to a reverse conduction thyristor having a thyristor electrode in the center and a diode electrode in the periphery.

[Brief explanation of drawings]

FIG. 381 is a sectional view of a main part of an embodiment of the present invention, and FIG. 2 is a conventional pressure contact type semiconductor device! ! ! Partial cross-sectional view. 1: silicon substrate, 2I molybdenum plate, 31 + thyristor electrode, 32: diode electrode, 4: upper contact electrode body,
5I lower contact electrode body, IO+ path conducting thyristor element. Figure 1 Figure 2

Claims (1)

[Claims] 1) Metal electrodes are provided at the center and the periphery on the upper surface, and a support plate serving as one electrode is brazed on the lower surface, and the electrodes on both sides of the semiconductor substrate are brought into pressure contact with the contact electrode body. 1. A semiconductor device characterized in that the thickness of an electrode provided at a portion is thicker than that of an electrode provided at a center.