JPH07283247A - Semiconductor device - Google Patents

Abstract

PURPOSE:To make brazing material optimal in thickness to enhance a semiconductor device in thermal and electrical properties by a method wherein particles higher in melting point than brazing material are mixed into the brazing material. CONSTITUTION:A semiconductor chip 3 is bonded to a fixing member 1 with a brazing material 7 interposed-posed between them for the formation of a semiconductor device, wherein particles 5 higher in melting point than the brazing material 7 are mixed into the brazing material 7. For instance, metal particles 5 of Mo, Ni, Cu or the like excellent in thermal and electrical conductivity and hither in melting point than the brazing material 7 are mixed into the brazing material 7, which is formed into a molded brazing material 6 whose thickness is equal to or twice as large as the grain diameter of the particles 5. The semiconductor chip 3 is mounted on the member 1 as a base through the intermediary of the particle-containing brazing material 6 of nearly the same size with the chip 3 and positioned, and the brazing material is fused in an inert gas atmosphere or a reducing gas atmosphere whose temperature is higher than the melting point of the brazing material 7 by a few to tens of degrees and solidified by cooling.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor chip which is brazed to a member such as a metal or a ceramic having good thermal conductivity, or a semiconductor which is brazed by a uniform brazing layer between the metal substrate and the ceramic. Regarding the device.

[0002]

2. Description of the Related Art Conventionally, a semiconductor device in which a metal composed of a semiconductor chip of this type and an electrode or a member having a metal layer on both surfaces, such as a ceramic having good thermal conductivity, is bonded with a brazing material has been disclosed in FIG. It was made of a member as shown in FIG. That is, the brazing filler metal 2 formed in a pellet shape having substantially the same size as the semiconductor chip is mounted on the base member, and the semiconductor chip 3 is mounted on the brazing filler metal 2.
In the positioned state, the brazing material is welded in an inert gas atmosphere or a reducing gas atmosphere having a temperature of several degrees to several tens of degrees higher than the melting point of the brazing material and is cooled and solidified.

The brazing between the semiconductor chip and the member makes an electrical and thermal connection together with a mechanical connection between the semiconductor chip and the member. From the viewpoint of electrical and thermal connection, the lower the electric resistance and the lower the heat resistance, the more preferable, and the thinner the brazing material layer, the better the characteristics of the semiconductor device.

[0004]

However, in the conventional semiconductor device, it is necessary to balance the electrical and thermal characteristics and the mechanical characteristics between the semiconductor chip and the member, so that the thickness of the solder layer is strict. Had to manage. For example,
If the supplied brazing filler metal flows out to an unnecessary portion, the thickness of the brazing filler metal layer becomes thin. Therefore, the brazing filler metal flow prevention portion is provided on the member 1, and the brazing filler metal flow prevention portion needs to be processed. . In addition, since the brazing material is made of a flexible material (for example, lead) for expansion and absorption, it has poor thermal and electrical conductivity.

[0005]

In order to solve the above problems, the present invention is applied to a semiconductor device having a structure in which a semiconductor chip and a member for fixing the semiconductor chip are connected by a brazing material. It is a mixture of particles having a melting point higher than that of the brazing material.

Further, the above-mentioned granular material is a metal having better thermal conductivity and better electrical conductivity than the brazing material.

The above-mentioned granular material is spherical.

The thickness of the brazing material formed is 1 to 2 times that of the granular material.

[0009]

Since the particulate material having a melting point higher than that of the brazing material is mixed in the brazing material, the optimum brazing material thickness is determined by the particulate material.

Since the granular material has better thermal conductivity and better electrical conductivity than the brazing material, the thermal and electrical characteristics of the semiconductor device can be improved.

Further, by making the granules spherical, it is possible to maintain the optimum thickness without stacking the granules in two stages.

Further, since the thickness of the brazing filler metal is formed and used to be 1 to 2 times the particle diameter of the granular material, it is possible to maintain the optimum thickness without stacking the granular materials in two stages during brazing. is there.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to FIG. 1 showing an embodiment. In the figure, 3 is a semiconductor chip, 1 is a metal serving as an electrode, a metal such as molybdenum / tungsten for heat buffering between the semiconductor chip and the metal substrate, and heat for insulating the semiconductor chip from the metal substrate having metal layers on both sides. It is a member of good conductivity such as ceramics. 6 is a brazing filler metal in pellet form,
Granular material 5 composed of a spherical metal, such as molybdenum, nickel, or copper, having a higher thermal conductivity and a higher electric conductivity than the melting point of the brazing filler metal is mixed therein.
Further, the granular material 5 is selected to have a size of 100 to 150 μm, and the thickness of the brazing material formed is selected to be 1 to 2 times the particle diameter of the granular material.

Then, a brazing material 6 containing a granular material having substantially the same size as the semiconductor chip is mounted on the base member, the semiconductor chip 3 is mounted on the brazing material 6, and the brazing material is positioned. The brazing material is welded in an inert gas atmosphere or a reducing gas atmosphere having a temperature of several degrees to several tens of degrees higher than the melting point of the material, and is cooled and solidified.

As described above, when the semiconductor chip 3 and the member 1 are brazed by using the brazing material containing the granular material, the granular material remains as shown in FIG.
The thickness between and is regulated by the granular material 5 and never falls below the particle diameter of the granular material 5. Further, when the semiconductor device molded in this way is used, the current path and the heat flow path are shared by the granular material 5 and the brazing filler metal portion 7 excluding the granular material 5, so that the conventional semiconductor device without granular material is used. Compared to
Since electric current and heat flow through the granular material having good heat conduction and good electric conduction, low electric resistance and heat resistance are obtained. Further, since the granular material is spherical and the thickness of the brazing filler metal is formed to be 1 to 2 times the particle diameter of the granular material, the granular material does not overlap in two stages during brazing, and the optimum thickness can be maintained. it can.

The above embodiment is applied to brazing between a semiconductor chip and a member, but between other members used in a semiconductor device, such as a heat buffer metal and a ceramic, a ceramic and a metal substrate, and the like. Also for brazing, it is possible to use a brazing material in which particles are mixed in the brazing material. Further, the thermal characteristics and electrical characteristics of the semiconductor device can be controlled by changing the mixing ratio of the granular material with respect to the brazing material.

[0017]

As described above, according to the semiconductor device of the present invention, the thickness of the brazing filler metal is determined to be the optimum value by the granular material,
It does not require strict control of the thickness of the brazing material as in the past. In addition, the thermal characteristics and electrical characteristics of the semiconductor device can be improved by the granular material. Further, it is not necessary to provide the member with a brazing filler metal flow preventing portion as in the conventional case.

[Brief description of drawings]

FIG. 1 is a sectional view of an embodiment of a semiconductor device of the present invention.

FIG. 2 is an explanatory diagram showing a component configuration state of a conventional semiconductor device.

3 is a cross-sectional view of the semiconductor device of FIG. 2 after brazing.

[Explanation of symbols]

 1 member 3 semiconductor chip 5 granular material 6 brazing material 7 brazing material part

Claims (4)

[Claims] 1. A semiconductor device having a structure in which a semiconductor chip and a member for fixing the semiconductor chip are connected by a brazing material, wherein a granular material having a melting point higher than that of the brazing material is mixed in the brazing material. Semiconductor device. 2. The semiconductor device according to claim 1, wherein the granular material is a metal having better thermal conductivity and better electrical conductivity than the brazing material. 3. The semiconductor device according to claim 1, wherein the particulate matter is spherical. 4. The semiconductor device according to claim 3, wherein the thickness of the formed brazing material is 1 to 2 times the particle diameter of the granular material.