JP2560518B2 - Method for manufacturing semiconductor device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention uses a soft solder to bond between a semiconductor piece and a conductor terminal connected thereto or between semiconductor pieces stacked as in a high-voltage rectifying device. To a method for manufacturing a semiconductor device.

[Conventional technology]

In manufacturing a semiconductor device, a soft solder is often used for connecting a semiconductor piece and a conductor terminal or for stacking a plurality of semiconductor pieces as in the case of a high-voltage rectifier. This is because the work is easy and there is no need to heat the semiconductor piece having the junction to a high temperature, so that the characteristics are not affected. Conventionally, various properties such as melting temperature and coefficient of thermal expansion of soft solder used in semiconductor devices have been controlled by the composition thereof. Further, in order to increase the reliability of bonding by setting the thickness of the brazing layer after brazing to a predetermined thickness, a brazing material containing a filler that does not melt at the brazing temperature has been devised. This filler-containing soft brazing filler metal has a particle size that is approximately the same as the thickness of the plate-shaped brazing filler metal used for brazing or the desired brazing layer thickness after brazing. It has a structure. Such a soft solder containing a filler is manufactured by inserting a filler into a soft brazing material such as solder when the soft brazing material is melted, and cooling the resulting ingot. Alternatively, when a strip-shaped brazing material is rolled and manufactured, a filler is sown on the screen or one side of the brazing material, and the filler is rolled into the solder and pressed into the solder.

[Problems to be Solved by the Invention]

The conventional filler-containing soft brazing material has the following problems.

(1) In the method of adding the filler to the molten brazing filler metal, it is difficult to control the distribution state of the filler, and thus the filler lumps are likely to occur in the brazing filler metal. When this lump of filler is exposed on the surface of the brazing material, there are some areas that are not brazed.

(2) When the filler is added to the molten brazing filler metal, if the specific gravity of the filler and the brazing filler metal greatly differ, the filler concentrates on the upper or lower portion of the molten brazing filler metal, resulting in uneven distribution of the filler in the ingot. Therefore, it is impossible to obtain a filler-containing soft brazing filler metal having a uniform distribution even after rolling.

(3) In the method of squeezing the filler on the surface during the rolling of the band-shaped brazing material and pushing it in, when the amount of the filler is large, the ratio of the filler occupying the surface portion increases and the brazing property decreases.

An object of the present invention is to solve the above problems and to provide a method for manufacturing a semiconductor device capable of forming a uniform joint having desired characteristics by using a soft solder containing a filler having a good brazing property. It is in.

[Means for solving the problem]

In order to achieve the above-mentioned object, the present invention provides a method for manufacturing a semiconductor device in which a semiconductor piece and a conductor terminal or between semiconductor pieces are joined together by brazing using a soft solder. It is brazed using a filler-containing soft brazing material obtained by rolling a laminated body having a layer containing a large amount of filler in a layered state.

[Action]

The surface is made of only soft solder, and the filler-containing soft brazing material obtained by rolling the laminate having the layer containing a large amount of filler in the layered state is almost free of filler on the surface. There is almost no filler in contact, and it does not hinder the bonding between the member and the wax. Further, since the molten brazing material and the filler are not mixed, there is no problem of specific gravity, and since the filler is present uniformly in the brazing material in a plane, uniform bonding occurs. In addition, since the filler-rich layer exists in layers in the soft brazing layer, the stress parallel to the bonding surface applied to the semiconductor piece is relaxed due to the difference in the thermal expansion coefficient between the conductor terminal and the semiconductor piece, and the thermal fatigue of the semiconductor device. Resistance and surge current limit characteristics are improved.

〔Example〕

Examples of the present invention will be described below with reference to the drawings.
FIG. 1 shows a solder plate 1 containing a filler used in one embodiment of the present invention, in which an average particle size is contained in a solder layer 2 of Pb / Sn = 90/10.
20 μm silicon particles are mixed as the filler 3.
The thickness of the solder plate 1 is 80 μm. This filler-containing solder plate 1 was manufactured by the method shown in FIGS. 3 (a) and 3 (b). That is, as shown in FIG. 3A, the filler 3 is sown on the band solder 21 having a thickness of 50 μm, three pieces of the filler 3 are stacked, and further one band solder 21 without the filler is stacked,
This laminated body 20 is rolled into rolls 31, 3 as shown in FIG.
2 was rolled to a thickness of 80 μm. As a result, a filler-containing solder plate in which the filler 3 was not exposed on the surface was obtained. Using this solder plate 1, a high voltage integer element as shown in FIG. 2 was manufactured. In the figure, the semiconductor piece 4 diffuses donors and acceptors from both sides of the Si substrate, and the Ni electrode 5
It was cut into a square after the provision of. The semiconductor pieces 4 were stacked by stacking the solder plates 1 containing filler, and the electrodes 6 on the heads of the conductor terminals 7 were brought into contact with both ends to be heated and soldered. Then, the side surface was covered with JCR8 and then sealed with resin 9. The rectifying element was brazed with a 90/10 solder plate having the same structure as this rectifying element and containing no filler, and the limiting characteristics against surge current were measured. The second rectifying element had twice the resistance. It was
This is considered to be due to the characteristics of the soldered part.

FIG. 4 shows a method for manufacturing a solder plate containing a filler according to another embodiment of the present invention, in which a long strip of solder 21 having a filler 3 is wound on it, and this is crushed in the vertical direction of the drawing to form a third plate.
A laminate similar to the laminate 20 in the figure is obtained. By rolling this, the filler-containing solder plate 1 having a filler layer structure inside can be produced.

Although the filler-containing solder plate 1 shown in FIG. 1 contains the filler 3 having a particle diameter of 1/4 of the target solder thickness, the solder plate 11 shown in FIG. 5 contains the target solder in the solder layer 2. Thick
Includes 1/3 particle size filler 3.

In the above examples, the reason why Si particles are used as the filler 3 is that particles having a uniform particle size are easily obtained. However, particles of a material with a higher melting point than other solders, such as Ag, N
Cu grains coated with i or Ag can also be used.
Since the filler is not mixed with the molten solder, the filler material can be arbitrarily selected. Also, Pb / Sn
Other soft solders can be used instead of solder.

〔The invention's effect〕

According to the present invention, the surface layer is made of a soft wax containing no filler, using a filler-containing soft solder plate prepared by rolling a laminate having a layer containing a filler layered inside,
By connecting the semiconductor pieces to each other or connecting the semiconductor pieces to the conductor terminals, the brazing property is improved and the brazing layer has a predetermined thickness, so that a highly reliable semiconductor device can be obtained. Further, since the filler layer has a layered structure parallel to the bonding surface, the stress generated in the brazing layer parallel to the bonding surface was relaxed.
Further, since the material of the filler can be arbitrarily selected, the effects obtained by the present invention are extremely large, such as the improvement of the resistance to surge current and the characteristics that cannot be controlled by the composition of the brazing material.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a solder plate containing a filler used in an embodiment of the present invention, FIG. 2 is a cross-sectional view of a high-voltage rectifying element manufactured according to an embodiment of the present invention, and FIG. 3 is the solder of FIG. An example of the manufacturing process of a board is shown, (a) is sectional drawing of a laminated body,
(B) is a cross-sectional view showing a rolling process of the laminate, FIG. 4 is a cross-sectional view illustrating another example of a manufacturing process of a filler-containing solder plate, and FIG. 5 is another filler-containing solder used in an embodiment of the present invention. It is sectional drawing of a solder plate. 1, 11: solder plate containing filler, 2: solder layer, 3: filler, 4: semiconductor piece, 6: electrode, 7: conductor terminal, 20: laminated body.

Claims (1)

(57) [Claims] 1. A method of manufacturing a semiconductor device in which a semiconductor piece and a conductor terminal or between semiconductor pieces are joined by brazing using soft solder, wherein a surface layer is made of only soft solder, and a layer is formed inside. A method for manufacturing a semiconductor device, which comprises brazing using a filler-containing soft brazing material obtained by rolling a laminate having a layer containing a large amount of filler.