JPS60241239A - Semiconductor device - Google Patents

Abstract

PURPOSE:To improve the heat dissipating characteristic by a method wherein an Si transistor is adhered to an Si carbide substrate of fin-integral structure. CONSTITUTION:A pellet 1 of Si transistor is made integral with the Si carbide ceramic substrate 2' with fins on one surface via solder layer 5. The substrate 2' is made of an SiC sintered body containing 0.1-3wt% of Be or Be compound. The solder layer 5 is made of Au-Si, and the Si is preferably contained at 3- 10atom%. Since an Si carbide substrate of fin-integral structure is used, the thermal fatigue resistance improves.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a semiconductor device, and particularly to a semiconductor device with excellent heat dissipation properties suitable for mounting a high-power semiconductor element.

[Background of the invention]

In semiconductor devices, high thermal conductivity, electrically insulating silicon carbide ceramics (thermal conductivity 20.6 W/'C1 Expansion coefficient: 4x
10-1'/°C or less) The use of the material as a semiconductor element support substrate has already been reported in JP-A-55-113042. However, in order to make radiation even more effective, heat radiation fins made of aluminum or copper are bonded to a silicon carbide substrate using solder or resin adhesive, as shown in Figure 1. There must be. However, since solder and resin adhesives generally have high thermal resistance and require a bonding process that tends to cause variations in performance, the structure shown in FIG. 1 cannot be said to be sufficient. Furthermore, since aluminum and copper used as the heat dissipation fins have a much larger coefficient of thermal expansion than the silicon carbide substrate, there is also the problem that the adhesive layer deteriorates due to heat cycles and thermal shock, resulting in increased thermal resistance.

[Purpose of the invention]

An object of the present invention is to correct the above-mentioned drawbacks, use the silicon carbide ceramic substrate having a fin structure to help dissipate heat generated in a semiconductor element, prevent thermal fatigue in the mounting part of the semiconductor element, and achieve high reliability. The present invention provides a semiconductor device having the following features.

[Summary of the invention]

In the semiconductor device using the silicon carbide ceramic substrate shown in FIG. 1, the thermal resistance of the solder or resin adhesive shown in 6 is about 10 times that of the silicon carbide ceramic or the heat radiation fins such as aluminum or copper. Therefore, 1
In order to improve the dissipation of heat generated in the semiconductor device, it is better to make the adhesive layer 6 as thin as possible, or to eliminate it if possible.

Furthermore, the silicon carbide substrate has a thermal expansion coefficient of 4X], 0
-'/℃ or less, while aluminum is 23X1
0-'/°C, and Cu is 1.7 x 10-'/°C, so there is a risk that the adhesive layer will deteriorate due to heat cycles and thermal NM after adhesion.

Therefore, in the present invention, as shown in 2' in FIG. 2, by using the silicon carbide substrate with fin processing on one side,
To improve heat dissipation by eliminating an adhesive layer with large thermal resistance, and to prevent deterioration of the adhesive layer by removing heat dissipating fins having significantly different coefficients of thermal expansion, thereby obtaining a highly reliable semiconductor device. was completed.

[Embodiments of the invention]

As shown in FIG. 2, the semiconductor device of the present invention has a solder layer 5 between the silicon transistor pellet 1 and the silicon carbide ceramic substrate 2' having fins on one side.
It is integrated through . It has been found that the heat dissipation performance of the semiconductor device obtained with such a structure is improved by about 20% compared to the case where metal heat dissipation fins shown in the structure of FIG. 1 are used. It is believed that this is because the adhesive layer 6, which has a large thermal resistance, was removed.

In a ceramic substrate made of a SiC sintered body, Be or a Be compound (Be o,
It has a composition consisting of a Sac sintered body containing (Be, C, etc.), and has a fin having the structure shown in the figure. After forming the product, sintering is carried out at 2000°C in vacuum under a pressure of 300°C/d, and the thermal conductivity at room temperature is 0.20CaQ/an sec.
・Has electrical resistivity of 1010 Ω or more at room temperature or higher.

Au-8i Ushida is used for the silicon pellet 1 and the substrate 2'. It is preferable that Si contains 3 to 10 atomic %. For these connections, silicon pellets may be made with or without Au vapor-deposited, and the substrate may be made with Au vapor-deposited in the same way, or 1 to 5% by weight of Au.
A paste made of glass or oxidized steel is baked into a thick film.

〔Effect of the invention〕

According to the present invention, since a silicon carbide substrate having a single-piece structure is used, it is not only effective in improving heat dissipation performance and thermal fatigue resistance, but also the process of bonding heat dissipation fins can be eliminated, thereby reducing the number of man-hours.

[Brief explanation of the drawing]

Figure 1 shows a conventional high thermal conductivity silicon carbide substrate and a gold-plated silicon carbide substrate.
FIG. FIG. 2 is an explanatory diagram of a semiconductor device using a fin-processed heat-generating conductive silicon carbide substrate according to the present invention.

Claims (1)

[Claims] 1. In semiconductor devices using high thermal conductivity and electrically insulating silicon carbide substrates, the previous ill! A semiconductor device characterized in that a silicon oxide substrate has a fin structure.