JPH06318608A - Flat semiconductor device - Google Patents

Abstract

PURPOSE:To unify the pressure applied to the electrode surface of a semiconductor substrate by making the inner surface of an electrode body a projecting surface with a high center part. CONSTITUTION:An electrode body inner surface 7 is formed as a spherical surface and the center part is raised. When the difference between the center part and the outer-periphery part of the electrode body inner surface 7 is made 5, 10, and 20mum, 5mum projecting surface has no effect, 20mum projecting surface causes a pressure equal to or larger than the twice the pressure at the outer- periphery part to be applied to the center part, which being undesirable, and 10 and 15mum projecting surfaces achieves a uniformly pressed state. The proper projection numeric value is proportional to the diameter of the electrode body. Therefore, when the diameter of the electrode body is made Dmm, it is desirable to raise the center part by 0.1-0.2D, thus unifying the pressure applied to the electrode surface of the semiconductor substrate when a connection conductor comes into pressure contact with the outer surface of the electrode body.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flat semiconductor device in which electrode bodies to which a connecting conductor is brought into pressure contact are exposed on both sides of a container.

[0002]

2. Description of the Related Art A flat semiconductor device having an electrode body that is pressed into contact with a connection conductor that also serves as a heat radiator has the advantage of increasing the current carrying capacity and heat dissipation capability, and is therefore well known as a power semiconductor device. . FIG. 2 conceptually shows an example of such a flat semiconductor device, in which a silicon substrate 1 brazed to a support plate 2 made of a material having a thermal expansion coefficient similar to that of silicon such as molybdenum is used as an insulating annular side wall 3. It is housed in a container composed of it and an electrode body 5 connected via a flange 4, and a conductive contact plate 6 is inserted on the side opposite to the support of the silicon substrate 1. When an external connecting conductor is brought into pressure contact with the electrode body 5, the contact body 6 is brought into pressure contact with the electrode surface of the upper surface of the semiconductor substrate 1, and the inner surface of the electrode body 5 is brought into pressure contact with the contact body 6 and the support plate 2. To do.

[0003]

However, in the conventional flat semiconductor device, the pressure applied to the electrode surface of the semiconductor substrate 1 becomes larger in the outer peripheral portion than in the central portion as shown in FIG. It's known. That is,
About 1.5 times larger pressure is applied to the semiconductor substrate in the outer peripheral portion than in the central portion. Due to such uneven pressure, the characteristics of the semiconductor device are impaired, and the electrode body 5 or the connection conductor is deformed.

An object of the present invention is to solve this problem and to provide a flat semiconductor device in which uniform pressure is applied to the electrode surface of the semiconductor substrate in both the central portion and the outer peripheral portion.

[0005]

In order to achieve the above object, the present invention is a support plate having a semiconductor substrate fixed to the inner surface of an electrode body exposed on both sides of a container accommodating the semiconductor substrate, or not fixed to the inner surface of the electrode body. In a flat semiconductor device that electrically and thermally conducts under pressure from the outside of the container via a contact plate, the inner surface of the electrode body has a high convex surface in the central portion. When the inner surface of the electrode body is a cylindrical body having a diameter Dmm, it is effective that the central portion is higher than the outermost peripheral portion by 0.1 to 0.2 Dμm. Further, it is effective that the inner surface of the electrode body is substantially spherical.

[0006]

When the inner surface of the electrode body is flat, the pressure applied to the electrode surface of the semiconductor substrate through the supporting plate or the contact plate and lower than the outer peripheral portion than the central portion causes the central portion of the inner surface of the electrode body to move. By increasing the height, the pressing force applied to the central portion increases, so that the pressure becomes uniform.

[0007]

1 is an exaggerated view of a flat semiconductor device according to an embodiment of the present invention, in which the same parts as those in FIG. 2 are designated by the same reference numerals. In this flat semiconductor device, the inner surface 7 of the electrode is formed as a spherical surface, and the central portion is raised. Diameter 80
In the electrode body 5 mm, the difference between the central portion and the outer peripheral portion of the inner surface 7 of the electrode is 5 μm, 10 μm, 15 μm and 20 μm.
It has been confirmed by actual measurement and numerical calculation that the distribution of the pressure applied to the electrode surface of the semiconductor substrate 1 by applying a force of 4 tons to the outer surface of the electrode body 5 is as shown in FIG. That is, if the projection is 5 μm, there is no effect, and
On the contrary, in the case of the μm convex, an excessive pressure more than twice as much as that of the outer peripheral portion is applied to the central portion, which is not preferable. A uniform pressure is applied to the 10 μm convex and 15 μm convex. This appropriate convex value is proportional to the diameter of the electrode body. Therefore, when the diameter of the electrode body is D mm, it is desirable to raise the central portion by 0.1 to 0.2D.

[0008]

According to the present invention, the inner surface of the electrode body exposed to the outer surface of the container is not a flat surface but a highly convex surface in the central portion, so that when the connecting conductor is pressed against the outer surface of the electrode body, the semiconductor substrate The flat semiconductor device can be obtained in which the pressure applied to the electrode surface can be made uniform, and the deterioration of the characteristics or the deformation of the container or the connecting conductor does not occur.

[Brief description of drawings]

FIG. 1 is a conceptual cross-sectional view of a flat semiconductor device according to an embodiment of the present invention.

FIG. 2 is a conceptual sectional view of a conventional flat semiconductor device.

FIG. 3 is a distribution diagram of pressure applied to a semiconductor substrate of the semiconductor device of FIG.

4 is a distribution diagram of pressure applied to a semiconductor substrate of the semiconductor device of FIG.

[Explanation of symbols]

 1 semiconductor substrate 2 supporting plate 3 container side wall 5 electrode body 6 contact plate 7 electrode inner surface

Claims (3)

[Claims] 1. A container for accommodating a semiconductor substrate is electrically connected to the inner surface of an electrode body exposed on both sides of the container through a support plate fixed to the semiconductor substrate or a contact plate not fixed to the container under electrical pressure from the outside of the container. A flat semiconductor device in which the inner surface of the electrode body has a high convex surface in the central portion in the thermally conductive one. 2. When the inner surface of the electrode body is a columnar body having a diameter Dmm, the central portion is 0.1 to 0.2D from the outermost peripheral portion.
The flat semiconductor device according to claim 1, which is higher by μm. 3. The flat semiconductor device according to claim 1, wherein the inner surface of the electrode body is substantially spherical.