JPH01111360A - Semiconductor device - Google Patents

Abstract

PURPOSE:To reduce a rate of occurrence of a package crack and a chip crack by a method wherein a radiating fin is formed by using aluminum nitride whose coefficient of thermal expansion is close to that of a ceramic package. CONSTITUTION:A radiating fin 9 is formed by using aluminum nitride whose coefficient of thermal expansion is close to that of a ceramic package 2. That is to say, the coefficient of thermal expansion of a copper-tungsten alloy CuW forming a bottom plate 1 is close to that of alumina Al2O3 forming the ceramic package 2; the coefficient of thermal expansion of aluminum nitride AlN forming the radiating fin 9 is improved as compared with the coefficient of thermal expansion of aluminum Al. By this setup, it goes without saying that a probability of occurrence of a package crack can be reduced; also the probability of occurrence ot a chip crack caused between a stage 3 and a semiconductor chip 4 can be reduced.

Description

[Detailed Description of the Invention] (Summary) The present invention relates to a semiconductor device, and in particular relates to the material of a radiation fin that is closely attached to a ceramic package through a bottom plate, and provides a semiconductor device capable of preventing the occurrence of package crank or chip crank. The package consists of a ceramic package having a bottom plate made of a copper-tungsten (Cub) alloy, a semiconductor chip housed in the bottom plate via a stage, and a heat dissipation fin attached to the bottom plate with resin. In the semiconductor device, the radiation fin is made of aluminum nitride having a coefficient of thermal expansion close to that of the ceramic package.

(Industrial Application Field) The present invention relates to a semiconductor device, and more particularly to the material of a radiation fin that is closely attached to a ceramic package via a bottom plate.

(Prior Art) Fig. 2 shows a cross-sectional view of a conventional ceramic package type semiconductor device with radiation fins. In the figure, 1 is a bottom plate which is brazed to a ceramic package 2. 3
is a stage, which is also soldered to the bottom plate 1. The bottom plate 1 and the stage 3 are made of copper-tungsten alloy (Cu (1
0χ)W(90χ) Coefficient of thermal expansion6. OxlO-/'c')
is used. Also, in stage 3, molybdenum a0
A coefficient of thermal expansion of 5.4 Xl0-'/°C is also used.

Reference numeral 4 denotes a semiconductor chip, which is diced and attached to the stage 3. Reference numeral 5 denotes a radiation fin, and aluminum, which has good thermal conductivity, is usually used.

A cap 6 protects the semiconductor chip 4, and is brazed to the ceramic package 2 via a seal frame (made of ICA Al1zOs). A seal ring (manufactured by Kovar) may be used instead of the seal frame 7. Reference numeral 8 indicates leads serving as input/output terminals of the semiconductor chip 4. A clad material Cu/Mo/Cu (coefficient of thermal expansion: 8.5 Xl0-'/°C) may be used for the bottom plate 1. [Problems to be Solved by the Invention] In the ceramic package type semiconductor device with heat dissipation fins having a conventional configuration, a crank occurs at the joint between the heat dissipation fins 5 and the bottom plate 1, and as a result, package cracks and chip cracks occur. There are drawbacks.

This is due to the thermal expansion coefficient of aluminum AlO forming the heat dissipation fins 5 to the copper-tungsten alloy of the bottom plate 1 bonded to match the thermal expansion coefficient of 6.7 Xl0-h/'C of the alumina Aigos forming the ceramic package 2. 23.
This is because the large difference in 86Xl0-'/''C causes stress to occur intensively at the joint between the two.

The present invention has been made in view of the above-mentioned conventional drawbacks, and an object of the present invention is to provide a ceramic package type semiconductor device with radiation fins that can prevent the occurrence of pancake crank and chip crank.

Means to solve problem C] FIG. 1 is a sectional view of a semiconductor device of the present invention.

Bottom plate 1 made of copper-tungsten (CuW) alloy
In the semiconductor device, the semiconductor device is constituted by a ceramic package 2 having: a semiconductor chip 4 housed in the bottom plate 1 via a stage 3; and a heat dissipation fin 9 attached to the bottom plate 1 with resin. The radiation fins 9 are made of aluminum nitride whose coefficient of thermal expansion is close to that of aluminum nitride.

[For production]

The material of the copper tungsten alloy is Cu(10χ)W(90χ
) or Cu (15X) W (85χ), the coefficient of thermal expansion is 6.0(6,5) x 10-
The coefficient of thermal expansion of the aluminum plate forming the ceramic package 2 is approximately 6.7X10-b/'C. When this is used as the material for the bottom plate 1 and the stage 3, and aluminum nitride/IN is used as the material for the radiation fins 9, its coefficient of thermal expansion is 4.5 Xl0-h/''C, which is significantly improved compared to the aluminum A1. This makes it possible to prevent package cranks and chip cranks from occurring.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings.

Note that, in order to make the explanation of the configuration and operation easier to understand, the same parts are given the same reference numerals throughout all the figures, and repeated explanation thereof will be omitted.

FIG. 1 shows a sectional view of a semiconductor device of the present invention.

In the figure, numeral 9 indicates a radiation fin made of aluminum nitride. Table 1 shows the relationship between the materials and thermal expansion coefficients of each part constituting this semiconductor device, including the members of the conventional example.

Table 1 Copper-tungsten alloy Cu forming the bottom plate 1 as shown above
W and alumina Al forming the ceramic package 2!
The coefficient of thermal expansion is similar to that of zOx, and aluminum nitride AI! which forms the radiation fins 9! The thermal expansion coefficient of N is also significantly improved compared to that of aluminum A1.

This not only reduces the probability of package crank occurrence, but also reduces the probability of chip crank occurrence between the stage 3 and the semiconductor chip 4.

In addition, aluminum nitride used for the radiation fins 9 has a high thermal conductivity <0.4 to 0.6 cal/sec, "C, cm).
Since the thermal conductivity is similar to that of conventional aluminum (0.5 cal/see, 'c, cm), the heat dissipation effect remains the same.

〔Effect of the invention〕

As is clear from the above description, the present invention has the effect of reducing the incidence of both package cranks and chip cracks.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a semiconductor device of the present invention, and FIG. 2 is a sectional view of a conventional ceramic package type semiconductor device with heat dissipation fins. In FIG. 1, 1 is a bottom plate, 2 is a ceramic package, 3 is a stage, 4 is a semiconductor chip, and 9 is a radiation fin.

Claims (1)

[Claims] A ceramic package (2) having a bottom plate (1) made of a copper-tungsten (CuW) alloy, a semiconductor chip (4) housed in the bottom plate (2) via a stage (3), and the bottom plate. In the semiconductor device comprising (1) and a heat dissipation fin (9) attached with resin, the heat dissipation fin (9) is formed of aluminum nitride having a coefficient of thermal expansion close to that of the ceramic package (2). A semiconductor device characterized by: