JPH0329348A - semiconductor equipment - Google Patents

Abstract

PURPOSE:To obtain an intermediate layer which is insulated electrically but which can conduct heat by a method wherein individual films laminated on a base plate are formed in a state that functions of electrical insulation between a semiconductor element and its base, of relaxation of stress, and of formation of a brazable face. CONSTITUTION:At least an insulating film 2 and a film 6 capable of being brazed well via stress-relaxing metal films 4, 5 are laminated on a container metal base plate 1; a semiconductor element 11 is brazed on the film 6 capable of being brazed well. That is to say, to films 4 to 6 which are provided individually with individual functions to insulate the semiconductor element 11 and the base plate 1, to absorb a thermal stress and an external stress due to a difference in a coefficient of thermal expansion between the semiconductor element 11 and the base plate 1 and to form a face capable of being brazed of the semiconductor element 11 are laminated between the semiconductor element 11 and the container metal base plate 1. Thereby, a thin intermediate layer which guarantees a good heat-conductive property can be formed; the degree of freedom to select a material is made high; the cost can be low.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a semiconductor device in which a semiconductor element is insulated and fixed onto a metal bottom plate that also serves as a heat sink of a container.

(Prior art) Even when a semiconductor element is housed in a container and a conductor connected to an electrode is drawn out from the container, the bottom plate that supports the semiconductor element needs to also serve as a heat sink, so it must be made of metal. ．Since this base plate and the semiconductor body must be electrically insulated, an insulating plate is inserted between the semiconductor body and the bottom plate.This insulating plate has high insulation properties to dissipate heat from the semiconductor body. It is also required to have good thermal conductivity.
Ceramics with good thermal conductivity such as beryllium oxide are used as such materials. Furthermore, this ceramic plate
In order to braze the semiconductor body and base temporary, copper and other materials are metallized on both sides by thermocompression bonding. [Problems to be Solved by the Invention] To manufacture the conventional semiconductor device as described above, first a semiconductor element is brazed to the metallized surface of a ceramic plate, and then this is temporarily brazed to the bottom. In this case, the brazing materials used for both brazing, such as solder, must have different melting points, which complicates the work. Furthermore, as mentioned above, ceramics having both high insulation properties and good thermal conductivity are expensive, and on top of that, they have to be metallized, which increases the cost. An object of the present invention is to solve the above-mentioned problems and provide a low-cost semiconductor device in which a semiconductor body is electrically insulated but supported on a metal bottom plate that also serves as a heat sink in a manner that allows heat conduction. It's about doing. [Means for solving the problem] In order to achieve the above object, the semiconductor device of the present invention has the following features:
A film with good brazeability is laminated on the metal bottom plate of the container via at least an insulating film and a stress-relaxing metal film, and a semiconductor element is brazed onto this film with good brazeability. [Function] Each film laminated on the slope of the bottom of the container, which also serves as a heat dissipation plate, provides electrical insulation between the semiconductor element and the bottom plate, stress relaxation, and the shape and function of the brazable surface of the semiconductor element as a whole. Appears while maintaining good thermal conductivity. Since the material for each membrane can be selected independently, there is a wide range of choices. [Example] Figures 1 and 2 show an example of the present invention. This semiconductor device has a transistor chip 11 housed in a container. The container has a bottom plate 1 made of Cu or M, and an insulating film 2 selected from SiO, Si (h.siJ4, amorphous Si, polycrystalline silicon, etc.) is deposited on the bottom film by chemical or physical vapor deposition method. .Cover by Svantha method etc. For example, 4K between 1l of chisop and bottom plate 1.
When a dielectric strength of V is required, SiJ with a thickness of 5Itm is used.
a. Provide a membrane. Thicker is better from an insulation standpoint, but thinner is better from a thermal conductivity standpoint. This absolute! ! In order to bond the insulating film and the upper film onto the film 2, a binder film 3 having good adhesion to both is laminated by a spunter method or a vapor deposition method. The binder film 3 is made of a thin film of Cr, Ti, or the like. On top of this, a stress relaxation film is provided to relieve thermal stress or mechanical stress based on the difference in thermal expansion coefficients between the semiconductor chip 11 and the bottom plate 1. In this case, the stress-relaxing film is formed by forming a stress-absorbing film 4 made of a relatively soft material such as Cu + P d + Au by sputtering, vapor deposition, plating, coating, etc., and then depositing a semiconductor layer thereon. A low thermal expansion coefficient film 5 made of Mo, W, etc. having similar thermal expansion coefficients is formed by chemical or physical vapor phase growth. It is laminated using spunter method, vapor deposition method, etc. Finally, a solderable film 6 with good brazing properties is coated with a thin film of Ni or the like by vapor deposition, Svanta method, plating method, or the like. The total thickness of these multilayer films 2.3, 4, 5.6 is 1
0fIa, and has good thermal conductivity as well as insulation due to the insulating film 2. In addition, these absolute &! [After the other films 3.4.5.6 except 2 are deposited on the entire surface of the bottom slope, the N regions of the chip support part and each electrode connection part of the chip are patterned by selective etching. The transistor chip 11 is brazed onto the well-brazed coating 6 of the chip support portion using a solder 7 such as solder. The use of Ni in the good brazeability coating 6 has the effect of preventing Sn from diffusing into the lower layer during soldering. The product lid iiitil2 of the transistor Chisob 11 is
The well-brazed coating 6 of the solder joint 13 is connected to the Aj wire 21 by bonding, and the emitter drawer 114 is brazed to the emitter joint 13. The base electrode 151 of the chip 11 is connected to the well-brazed coating of the base connection part 15 by bonding with the M wire 21, and the base drawer board 16 is brazed to the base connection part. The collector electrode on the bottom surface of the chip 11 is brazed to the uppermost layer of IP16, which has good brazing properties, but the binder l of the multilayer film is
I! 3 and the stress-absorbing film 4 are extended on the edge film 2, and a collector lead 22 is formed between it and the collector connection part 17. A collector lead 18 is brazed to the collector connection part 17. As conceptually illustrated in FIG. 1, a container top 8 is glued to the edge of the container bottom plate 1. [Effects of the Invention] According to the present invention, there is insulation between the semiconductor element and the bottom plate of the container that also serves as a heat sink, and thermal stress due to the difference in thermal expansion coefficient between the semiconductor element and the bottom plate. By laminating films that individually have the functions of absorbing external stress and forming a brazable surface of the semiconductor element, it can be formed as a thin intermediate layer that guarantees good thermal conductivity. The degree of freedom was increased, and material costs and man-hours could be reduced, resulting in a low-cost semiconductor device.

[Brief explanation of drawings]

Figure 1. FIG. 2 shows a semiconductor device according to an embodiment of the present invention, FIG. 1 is a sectional view, and FIG. 2 is a plan view.

Claims (1)

[Claims] 1) A film with good brazeability is laminated on the metal bottom plate of the container via at least an insulating film and a stress-relaxing metal film, and a semiconductor element is brazed onto the film with good brazeability. Semiconductor equipment.