JPH0661387A - Semiconductor device heat dissipating board - Google Patents

Abstract

PURPOSE:To enable a heat dissipating board to keep a semiconductor chip high in airtightness, to be formed lightweight, and to be kept high enough in heat dissipating properties and processability to cope with densification of a semiconductor device by a method wherein the heat dissipating board is composed of a flat plate of silicon carbide compact and a heat dissipating fin equipped with a large number of hollow pin members of silicon carbide porous body. CONSTITUTION:A heat dissipating board is composed of a flat plate 1 of silicon carbide solid body where a semiconductor chip is mounted and a heat dissipating fin 3 which is of silicon carbide porous body 10 to 40% in voids and bonded to the other side of the flat plate 1 opposite to a semiconductor chip. By this setup, a mounted semiconductor chip is prevented from coming into contact with air so as to be effectively kept high in airtightness, and the heat dissipating fin 3 is slightly lessened in thermal conductivity as compared with one formed of silicon carbide compact but the heat dissipating board can be remarkably improved in processability, lessened in weight, and sharply enhanced in productivity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device heat dissipation board on which a semiconductor chip can be mounted, and more particularly to a semiconductor device heat dissipation board capable of efficiently dissipating heat generated from the semiconductor chip.

[0002]

2. Description of the Related Art Recent electronic devices tend to increase the amount of heat generated by semiconductor chips due to the increase in the density of semiconductor devices accompanying the increase in the amount of information and the diversification of demand. In order to dissipate this heat, It is customary to attach various heat dissipation substrates to the semiconductor device.

Conventionally, as the heat dissipation substrate, a substrate made of ceramics such as aluminum nitride, silicon nitride, and silicon carbide has been used. However, although these substrates do not have a bonding defect such as peeling due to a difference in thermal expansion with a semiconductor chip to be mounted, and although some progress can be seen,
In addition, it is necessary to improve the heat conductivity (so-called heat dissipation) and the weight, and it is not possible to sufficiently meet the demand for higher density of the semiconductor device.

On the other hand, various heat dissipation substrates have been proposed, which have the drawbacks of the above-mentioned ceramics substrates, that is, the heat dissipation and the lightness are improved. Examples thereof include a silicon carbide substrate having a fin structure (JP-A-60-241239) and a ceramic substrate (JP-A-3-79064) in which a plurality of pin-shaped members are joined.

The conventional heat dissipation boards proposed in these publications have fin structures in all of the heat dissipation parts, so that the heat dissipation board is superior to the heat dissipation board having only a flat plate in addition to the heat dissipation board. It is also lightweight.

[0006]

However, in the case of the above-described conventional heat dissipation substrate, the silicon carbide substrate having the fin structure has a problem that it is hard and brittle because the member is a dense body and has very poor workability. there were. On the other hand, a substrate having a plurality of pin-shaped members bonded to each other has better heat dissipation than a flat plate only, but there is a limit to obtaining heat dissipation sufficient to deal with high density of semiconductor devices. .

[0007] Therefore, the present invention aims to obtain a heat dissipation substrate that can overcome the problems of the prior art, and in particular, to sufficiently cope with the high density of semiconductor devices while maintaining the excellent lightness of the fin structure. Provided is a heat dissipation substrate for a semiconductor device, which has excellent heat dissipation properties and excellent workability.

[0008]

As a result of intensive studies to realize the above-mentioned object, the inventors of the present invention have made the above-mentioned problem advantageous by forming a heat dissipation substrate for a semiconductor device as shown below. As a result of finding a solution, the present invention has been completed.

That is, according to the present invention, in a heat dissipation substrate for a semiconductor device on which a semiconductor chip can be mounted, a surface on which the semiconductor chip is mounted is constituted by a flat plate made of a dense body of silicon carbide, and the other surface is porous of silicon carbide. A heat dissipation substrate for a semiconductor device, comprising a plurality of hollow pin-shaped members made of a material, each of which is formed by a heat dissipation fin.

[0010]

The heat radiation substrate for a semiconductor device of the present invention is characterized by comprising a flat plate made of a silicon carbide dense body and a heat radiation fin having a large number of hollow pin-shaped members made of a silicon carbide porous body protruding therefrom. It is in.

With such a structure, the airtightness of the semiconductor chip can be maintained and the weight thereof can be reduced, and further, the semiconductor chip has excellent heat dissipation capable of coping with high density of the semiconductor device. It is possible to provide a heat dissipation board for a semiconductor device which is excellent in workability.

FIG. 1 is a diagram showing an example of a heat dissipation substrate for a semiconductor device of the present invention. Reference numeral 1 in the drawing is a flat plate made of a silicon carbide dense body, which is a member on which a semiconductor chip is mounted. The reason why the material of the flat plate 1 is a silicon carbide dense body is that when a semiconductor chip is mounted, the semiconductor chip can be prevented from coming into contact with air and the airtightness of the semiconductor chip can be effectively maintained. The flat surface 1 may be provided with a Ni, Au plating layer 2 on the semiconductor chip mounting surface in order to improve the adhesion of the semiconductor chip to the substrate.

A radiating fin 3 made of a porous silicon carbide body having a porosity of 10 to 40% is joined to the side of the flat plate 1 opposite to the semiconductor chip mounting surface. This radiation fin 3
The reason for using a porous body having a porosity of 10 to 40% is that the workability of the substrate can be significantly improved although the thermal conductivity is slightly lower than that of the dense body.

The heat radiation fin 3 comprises a base 3a and a large number of hollow pin-shaped members 3b protruding from the base 3a. The reason for providing a large number of hollow pin-shaped members 3b is that the surface area of the radiating fins 3 is about twice as large as that of the conventional solid pin-shaped member, and the heat radiation performance of the substrate is improved by about 1.5 to 2.0 times. Is. The hollow pin-shaped member 3b may have any cross-sectional shape as long as it has a pin shape, and may have, for example, a triangular cross-section or a square cross-section. Particularly, in consideration of the extrudability, a square cross-section is preferable.

As described above, since the heat dissipation substrate for semiconductor device of the present invention is provided with the heat dissipation fins having the above-mentioned structure, it has an excellent heat dissipation property capable of sufficiently dealing with high density of the semiconductor device. Therefore, when the semiconductor chip is mounted on this substrate, the heat generated from the semiconductor chip can be efficiently dissipated, and the error due to the temperature rise of the semiconductor chip can be surely prevented.

Further, the heat dissipation substrate for semiconductor device of the present invention is
Since the radiation fin of porous silicon carbide with porosity of 10 to 40% is used, it is possible to reduce the weight of the radiation substrate, and moreover, it is easier to process than the dense body, and The productivity can be greatly improved.

Next, the heat dissipation substrate for semiconductor device of the present invention is
For example, it can be manufactured by the following method (see FIG. 2). First, a binder is added to silicon carbide powder and kneaded, and then extrusion molding is performed to obtain a molded product having a predetermined shape (see FIG. 2 (a)). As the silicon carbide powder, it is preferable to use a mixed powder of powders having an average particle size of 0.2 to 8 μm. The reason for this is that the porosity of the porous body can be controlled in various ways by mixing powders having different average particle sizes. As the binder, a known resin such as methyl cellulose can be used.

Next, the molded body is bonded to a flat plate made of a dense body of silicon carbide, degreased in a firing furnace and then fired to obtain a sintered body having a predetermined shape (see FIG. 2 (b)). . This joining is performed, for example, by using silicon carbide powder (average particle size 0.2 to 8 μm).
m) resin (α-terpineol and methyl cellulose)
Is added to obtain a paste having an appropriate viscosity.

Then, in the radiating fin forming portion of the sintered body, cuts are formed in the vertical and horizontal directions for forming a large number of independent hollow pin-shaped members as shown in FIG. 1 (b). By this cutting process, it is possible to obtain a heat dissipation board for a semiconductor device in which a large number of hollow pin-shaped members are projected in the heat dissipation fin portion (see FIG. 2 (c)).

The semiconductor chip bonding surface of the substrate thus obtained may be plated with Ni or Au, if necessary, to improve the adhesiveness of the semiconductor chip to the substrate. This also makes it possible to improve the reliability of the semiconductor device.

[0021]

[Example] SiC powder (mixed powder of particle size 0.2 μm and 8 μm) was kneaded by adding a binder and then extruded to form 30 × 30 mm, length 200 mm, square 2 mm, wall thickness 0.3 m
A molded body of m was obtained. Next, the above-mentioned molded body was cut into 15 mm widths, and a SiC flat plate (30
X 30 x 2 mm) were joined and degreased and fired in a firing furnace. Then, a notch having a depth of 10 mm is formed in the radiating fin forming portion (lattice portion) for forming the pin-shaped member, while Ni plating (film thickness 2 μm) and Au plating (film thickness 0.25) are formed on the flat surface of the semiconductor chip bonding surface. μm) to produce a heat dissipation substrate for a semiconductor device.

A semiconductor chip was bonded to the heat-radiating substrate for a semiconductor device with Ni and Au plating thus obtained, and its thermal characteristics were examined. As a result, compared with the conventional heat dissipation board for semiconductor devices that has a pin structure made of dense SiC, the heat dissipation is 1.
It was confirmed that it improved 8 times.

Further, the workability of the heat dissipation substrate was examined by measuring the time required to make a cut having a depth of 10 mm in the lattice portion. As a result, the processing time of the conventional substrate composed of a dense SiC body was 21 hours and 20 minutes, whereas the processing time of the substrate of the present invention was 1 hour and 4 minutes, and the workability of the substrate can be significantly improved. I understood.

Further, the weight of the radiation fin was measured to examine the weight reduction of the substrate. As a result, conventional SiC
It was found that the weight of the heat radiation fin of the present invention was 15.3 g, while the weight of the heat radiation fin made of a dense body was 21.9 g, and the weight of the substrate can be reduced.

[0025]

As described above, the heat dissipation substrate for a semiconductor device of the present invention is a heat dissipation fin in which a flat plate made of a silicon carbide dense body and a large number of hollow pin-shaped members made of a silicon carbide porous body are provided in a protruding manner. Since it is composed of and, it is possible to maintain the airtightness of the semiconductor chip as well as to reduce the weight, and also has an excellent heat dissipation property that can sufficiently cope with the high density of the semiconductor device, and further it is easy to process. It is possible to provide an excellent heat dissipation substrate for a semiconductor device.

[Brief description of drawings]

FIG. 1 shows an example of a heat dissipation substrate for a semiconductor device of the present invention.
It is a front view and (b) sectional drawing.

FIG. 2 is a diagram showing an example of a method for manufacturing a heat dissipation board for a semiconductor device of the present invention.

[Explanation of symbols]

 1 Flat plate 2 Ni, Au plating layer 3 Radiating fin 3a Base 3b Hollow pin-shaped member

Claims (1)

[Claims] 1. In a heat dissipation substrate for a semiconductor device on which a semiconductor chip can be mounted, a surface on which the semiconductor chip is mounted is constituted by a flat plate made of a silicon carbide dense body, and the other surface is made of a silicon carbide porous body. A heat dissipation board for a semiconductor device, comprising a plurality of heat dissipation fins provided with protruding hollow pin-shaped members.