JPS61141148A - Semiconductor device - Google Patents

Abstract

PURPOSE:To facilitate the deformation of a contact electrode plate as well as to contrive improvement in thermal resistivity of a semiconductor device having the split electrode such as a GTO thyristor, the characteristics of forward voltage drop, or the characteristics of electric wave cut-off by a method wherein air gap is provided on the back side of the contact surface of the contact electrode plate and a semiconductor element. CONSTITUTION:Grooves 5 are provided on a contact electrode plate by performing a machine work in longitudinal and lateral directions on the side reverse to the contact surface with the semiconductor element of a contact electrode plate 3 consisting of a molybdenum plate, for example. It is desirable that the width of said groove 5 is 1.0mm or less for the purpose of securing the contact area of the contact electrode plate 3. When pressure is applied to the above-mentioned contact electrode plate 3 from the side where a groove forming work is performed, the width of the perforated part of the groove 5 is made wider, the contact electrode plate 3 is clamped between the curved surface of the cathode electrode 13 of a semiconductor substrate 1 and the lower surface of an upper electrode body 22 which is plastically deformed, and the contact electrode plate 3 can be uniformly contacted to both surfaces. As a result, the effective area of electrode can be stabilized, and the variation in characteristics pertaining to the area of electrode caused by the application of pressure can also be removed.

Description

[Detailed description of the invention] [Technical field to which the invention pertains]

The present invention relates to a semiconductor device in which a common contact electrode plate is pressed into contact with electrodes provided separately on the main surface of a semiconductor body.

[Prior art and its problems]

FIG. 2 shows a cross-sectional shape of a gate turn-off (hereinafter abbreviated as GTo) thyristor as an example in which electrodes are divided and arranged on the main surface of a semiconductor element. In FIG. 2, a semiconductor body 1 includes a silicon plate 11 having a gate electrode 12 and a cathode electrode 13 arranged separately, and a molybdenum plate made of a material with a low expansion coefficient such as tungsten by a brazing material 14 made of aluminum or aluminum. A new board! 5 and is heat treated and integrated. In this integration step, the semiconductor element l is formed by a silicon plate 11
It is curved due to the bimetallic effect caused by the difference in coefficient of thermal expansion between the substrate 15 and the substrate 15, and the degree of the curve increases as the diameter increases, as shown in FIG. As shown in No. 3m, the magnitude of the bend between the center and the periphery of the semiconductor element is, for example, when the substrate 15 is made of a molybdenum plate.
For a semiconductor element having a diameter of 64 cm, the diameter of about 100-185 days increases by about 200 am. This semiconductor element 1 is used by being incorporated into a container (for example, Fig. 4-)
As shown in the figure, the semiconductor body 1 is placed on the electrode body 21, and the contact electrode plate 3 made of a molybdenum plate is placed on top of the lead 114.
1.1, the gate member consisting of the edge plate 42 is pressed against the gate electrode 12 by the spring 43. Further, the upper electrode body 22 is placed on the divided cathode electrode 13 which is the main electrode via the contact electrode plate 3, and the cathode electrode 1 in the center
3 are combined in such a way that only 3 are in contact with the electrode plate 3. When a tightening pressure is applied to the state shown in FIG. 4+al, the bending of the semiconductor body 1 is corrected and expanded due to the pressure, as shown in FIG. This tightening pressure and the contact state, in which However, this increase in clamping pressure may induce destruction due to increased stress due to compression of the semiconductor element 1, and the pressure mechanism is also complicated. Since the device becomes large and expensive, it is not possible to increase the pressure indefinitely.

[Object of the Invention] The present invention provides a semiconductor device that eliminates the above-mentioned drawbacks and provides uniform pressurized contact between the divided electrodes of a semiconductor element and a common contact electrode plate with appropriate clamping pressure. The purpose is to provide. Summary of the Invention According to the present invention, the contact electrode plate has flexibility because it is composed of a large number of adjacent parts with narrow gaps between them on the back side of the contact surface with the semiconductor element. The above object is achieved because it can be easily deformed along a curve.

[Embodiments of the invention]

FIG. 1 shows the structure of a contact electrode plate in an embodiment of the present invention. Grooves 5 are machined vertically and horizontally on the opposite side of the contact electrode plate 3 made of, for example, a molybdenum plate to the contact surface with the semiconductor body.
is provided. The width of this groove 50 is preferably 1.0 mm or less from the viewpoint of securing the contact area of the contact electrode plate 3. When pressure is applied to such a contact electrode plate 3 from the grooved surface side, the width shown in FIG. 1 (0) is obtained. The width of the opening of the groove 5 widens as shown in FIG. can be contacted. This makes the effective electrode area constant, and the characteristics related to the electrode area do not change due to pressure. Figures 6 to 8 respectively show the contact electrode plate.
This shows one interesting embodiment. In FIGS. 6 and 7, concentric grooves 5 are provided in the contact electrode plate 3 in consideration of workability. FIG. 6 shows a contact electrode plate structure in which grooves are formed at equal intervals, which is suitable for bending the curved semiconductor body l. In FIG. 7, dense concentric grooves 5 are provided in the periphery of the semiconductor body 1 where the curve is large. In the embodiment shown in FIG. 8, the ring 61 has a different diameter.
．． 62 and 63, a disk 71 is fixed to one side by brazing or the like so that a gap 51 is created between them, and a cap having an edge adapted to the outer diameter of the outermost ring 63 is attached to the other side. 72 to form the contact electrode plate 31 and the camp 72 have a diameter of, for example, 0.05 to 0.5 mm.
Since the contact electrode plate 31 is made of a thin molybdenum plate and can be easily deformed, the contact electrode plate 31 is easily bent by the clamping pressure between the semiconductor body 1 and the upper electrode body 22. In this case, the gap 51 is narrower on the side in contact with the cap 72 (such an electrode contact plate 31 is a circular plate on both sides of the rings 61 to 63).
1 and the cap 72, it is possible to prevent deformation and damage caused by the semiconductor body 1 or the upper electrode body 22 biting into the gap JF51. Further, as the material of the electrode contact plate 31, copper, which has high electrical conductivity and malleability, can be used, which has the effect of reducing contact resistance with the electrode 13 and being cheaper than molybdenum or the like.

【Effect of the invention】

As described above, according to the present invention, the contact electrode plate can be easily deformed by providing a gap on the back side of the contact surface of the contact electrode plate with the semiconductor body. As a result, the bending caused by the bimetallic effect caused by the difference in the coefficient of thermal expansion of the materials constituting the semiconductor element body can be corrected by the tightening pressure, and the contact electrode plate deformed by the tightening between the element body and the upper electrode body can be adapted to the bending. This makes it possible to obtain uniform contact all the way to the periphery of the semiconductor element, which improves the thermal resistance, forward voltage drop characteristics, or current cutoff characteristics of semiconductor devices with split electrodes, such as GTO thyristors, and makes it possible to use complex pressurizing mechanisms. Since it can be obtained without using it, its effect is extremely large.

[Brief explanation of drawings]

FIG. 1 shows a contact electrode plate in one embodiment of the present invention,
2) is a plan view, (bl is a sectional view taken along line A-A of lal,
The figure is a sectional view of an example of a semiconductor element of a GTO thyristor in which the present invention can be implemented, Figure 3 is a relationship diagram between the diameter and bending amount of the semiconductor element as shown in Figure 2, and Figure 4 is a diagram according to the present invention. A cross-sectional view of an example of a GTO thyristor that can be implemented with +Ill
is before pressurization, fbl is after pressurization, FIG. 5 is a relationship diagram between clamping pressure and thermal resistance of the GTO thyristor, and FIGS. 6 and 7 are contact electrode plates in different embodiments of the present invention, respectively. 21: a lower electrode body; 22: upper electrode body,
3.31+contact electrode body, 5: groove, 51: void load 61.6
2.63 F ring, 71: disc, 72: cap. Figure 1, Figure 2! ! 1 Figure 3 Figure 4. Fifth! m Column 7

Claims (1)

[Claims] 1) In a device in which a common contact electrode plate comes into pressure contact with electrodes provided separately on the main surface of a semiconductor element, the contact electrode plates are adjacent to each other through a narrow gap on the back side of the contact surface with the semiconductor element. A semiconductor device characterized in that it consists of a large number of parts.