JPH10261660A - Electrode of laminated structure and manufacture therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the usage of Mo, a rare metal, to reduce the entire cost and obtain an electrode of laminated structure with a high breakdown voltage and reliability maintained which can be used in a wide variety of applications as a substitute for Mo electrode by forming both the ends in the direction of lamination from a Mo layer in a laminate formed by alternately laminating Mo layers and a Cu layer. SOLUTION: The electrode is a laminate, formed by alternately laminating Mo layers 12 and a Cu layer 14. Both the ends of the laminate in the direction of lamination are formed on the Mo layers 12 having the same thickness, and the layers 12, 14 constituting the laminate are jointed with one another using brazing material 21. For example, an electrode 7 of laminated structure for use in semiconductor devices is formed by jointing Mo parts 12, 12 with upper and lower base 15, formed on a Cu part 14 on the upper and lower sides, using brazing material 21. Further, for example, the parallelism of the mating faces of the Mo layers 12 and the Cu layer 14 is controlled to within 5 μm/10mm or below, and either or both of the Mo layers 12 and the Cu layer 14 are plated with Ni. In addition a brazing material 21 containing Ag and Cu is used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated electrode and a method of manufacturing the same, and more particularly, to a laminated electrode used for an electrode directly contacting a semiconductor chip used in a high power device and a method of manufacturing the same.

[0002]

2. Description of the Related Art Silicon (S) used for high power devices
i) Metal molybdenum (Mo) is used as an electrode directly used for the chip. Mo has the advantage that the thermal expansion is smaller than other metals and the thermal expansion coefficient is close to the thermal expansion coefficient of the Si chip. Further, Mo has a higher thermal conductivity than ceramics or the like, and has a function of releasing heat generated from the Si chip and preventing thermal destruction of the Si chip.

[0003] Manufacturing of a Mo electrode by a conventional method has been performed as follows.

FIG. 8 is a diagram for explaining a method of manufacturing a Mo electrode according to a conventional method. First, as shown in FIG. 8A, a Mo plate 51 is used as a material. Mo plate 51
Is a plate rolled by a roll having a Mo purity of 99.9% or more, and a plate having a thickness corresponding to the product thickness and a polishing allowance is prepared.

[0005] Next, as shown in FIG. 8B, the rectangular plate 52 is cut by a cotter machine (roughing). FIG.
In (b), a dashed line indicates a cutting line.

[0006] Next, as shown in FIG.
Is cut with a milling machine, the dimensions are set, and the squareness is set, to obtain a processed plate 53. The upper and lower surfaces are polished or wrapped to increase the thickness.

Further, as shown in FIG. 8 (d), a hatched portion of the polished work plate 53 shown in the left diagram is scraped off by milling and stepped to obtain a Mo electrode 54 product shown in the right diagram. .

[0008]

However, an electrode using Mo is harder than iron (Fe) or copper (Cu), consumes a lot of tools at the time of processing, takes a long time to process, and requires a high processing cost. There was a drawback of becoming high.

[0009] In particular, as described above, in the case of products that require step processing, the cutting allowance is large and material is wasted.
Furthermore, since Mo is a rare metal, its material is expensive, and its use has been limited to some devices that require high withstand voltage and high reliability.

[0010] Therefore, the technical problem of the present invention is to reduce the amount of Mo, which is a rare metal, to lower the overall cost,
Another object of the present invention is to provide a multilayer structure electrode which can be generally used as a substitute for a Mo electrode maintaining high withstand voltage and high reliability, and a method of manufacturing the same.

[0011]

According to the present invention, there is provided a laminate in which Mo layers and Cu layers are alternately laminated, wherein the laminate has a Mo layer having the same thickness at both ends in the laminating direction. Each layer constituting the laminate is joined by using a brazing material to obtain a laminated electrode.

Further, according to the present invention, there is provided a laminated structure electrode in which at least one of the Mo layer and the Cu layer is plated with Ni in the laminated structure electrode.

Further, according to the present invention, in the laminated electrode, the brazing material contains Ag and Cu.

Here, in the present invention, Ag and Cu
As a brazing filler metal containing, BAg-8 (Ag 72% Cu 28%) specified in JIS Z-3261 is preferable.

According to the present invention, there is provided any one of the above-mentioned laminated electrodes having a thermal conductivity of at least 300 W / m · K.

Further, according to the present invention, there is provided a method of manufacturing a laminated structure electrode characterized in that the flatness of the joint surface between the Mo layer and the Cu layer is 5 μm / 10 mm or less, and the layers are alternately brazed. Can be

[0017]

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

FIG. 1 is a schematic sectional view of a semiconductor device using a laminated electrode according to an embodiment of the present invention.

Referring to FIG. 1, a semiconductor device 10 includes a Si chip 1 as a semiconductor chip, a heat compensator 2 on which the Si chip 1 is mounted, a collector electrode 3 provided on the bottom of the heat compensator 2, A stacked electrode 7 provided on the chip, an emitter electrode 4 provided above the stacked electrode 7, and a gate electrode extending upward from the Si chip 1 adjacent to the stacked electrode 7 and the emitter electrode 1. 6, a Teflon guide 5 in the form of a square tube that covers the periphery thereof, and sealing members 8a and 8b made of ceramic that cover the upper and lower ends of the Teflon guide 5 by exposing the respective electrodes. .

FIG. 2 is a perspective view showing the laminated electrode 7 used in the semiconductor device of FIG. As shown in FIG.
The laminated structure electrode 7 is a copper (Cu) component 1 having a base 15.
The Mo parts 12, 12 are mounted on the upper and lower
Have a configuration in which they are joined together.

FIG. 3 to FIG. 7 are views sequentially showing the steps of manufacturing the laminated electrode 7 of FIG. The manufacturing process of the laminated structure electrode 7 will be described with reference to FIGS.

As shown in FIG. 3, first, as a raw material, a pure Mo plate 1 having a purity of 99.9% or more, which is processed by rolling.
1 was prepared.

Next, as shown in FIG. 4, Mo pieces are punched out of the pure Mo plate 11 by a press machine. Here, in order to guarantee a flatness of 10% or less in void ratio, the surface to be a brazing surface of each Mo component is formed into a flatness of 5 μm / 10 mm or less and becomes a Mo component 12.

On the other hand, separately from the Mo plate 11, as shown in FIG. 5, an oxygen-free copper plate 13 is prepared as a Cu material.

Next, as shown in FIG. 6, step forming press working is performed by press working. The surface of the upper and lower steps 15 serving as a brazing surface needs to have a flatness of 5 μm / 10 mm in order to guarantee a void ratio of 10% or less.

Next, as shown in FIG. 7A, a groove 1 having a shape corresponding to the product shape is formed in a carbon jig 17 serving as a base.
On the other hand, a hole 19 corresponding to the product shape is formed in the carbon jig 16 serving as a lid, and the groove 18 and the hole 1 are formed.
9 forms a pocket portion. Each part is inserted into this pocket.

As shown in FIG. 7B, the parts to be inserted are Mo parts 12, BAg-8 (JIS Z-326).
1, see)), Cu parts 14, BAg
-8 are inserted into the carbon jig in this order. Mo part 12 and Cu part 1 at this time
It is preferable to apply plating (Ni, Ag, or Au) for improving the brazing property as one of the pretreatment to one or both of them. The carbon jigs 16 and 17 into which these laminated parts are inserted are passed through a furnace provided with a reducing atmosphere, and a maximum of 8
Perform brazing at 30 ° C. or higher.

Through the above steps, the laminated electrode 7 shown in FIG. 2 is manufactured.

The thus-produced laminated electrode 7 has
By performing the step processing on the Cu component 14, the usage amount of Mo can be reduced. In addition, Cu parts 14
By adjusting the height of the step, the thickness of the Mo parts 12 bonded on both sides is made the same so that the same parts can be used.
The structure sandwiched between o-plates prevents deformation due to the difference in thermal expansion with Cu.

When one surface is made of Cu, Mo
Although soft Cu is preferentially wrapped and partially reduced as compared with the above, in the embodiment of the present invention, in the laminated structure electrode 7, this is prevented by sandwiching both sides with Mo plates, and the total Thickness adjustment, surface accuracy (flatness,
Double-sided lapping for the purpose of parallelism) can be easily performed.

(Specific Example) Next, a specific example of the production of the laminated electrode according to the embodiment of the present invention will be described with reference to FIGS. 2 to 7 again.

As shown in FIG. 3, the thickness is 1.0 mm and the width is 6 mm.
5mm, 300mm length, 99.9% Mo rolled plate 1
1 was prepared.

Next, as shown in FIG. 2, a Mo plate piece was sized to a size of 17 mm square and a thickness of 1.0 m by a punching press machine.
m. Here, the surface is set to a flatness of 30 μm / 10
mm or less, and the surface is plated with Ni having a thickness of 2 μm to obtain Mo parts 12. Here, Ni plating is performed to increase the reliability of brazing.

On the other hand, as shown in FIG.
An oxygen-free copper plate 13 having a thickness of 2.5 mm, a width of 20 mm, and a length of 300 mm was prepared.

As shown in FIG. 6, a 20 mm square, 2.5 mm thick stepped shape having a 17 mm square base 15 on both sides is pressed by a punching press machine.
This is referred to as a Cu component 14.

Next, as shown in FIG. 7B, the Mo part 12, the brazing material 21, the Cu part 14, the brazing material 21, and the Mo part 12 are sequentially placed on the carbon jig 20 shown in FIG. insert. Here, BAg-8 (Ag 72% Cu 28%) having a square of 10 mm and a thickness of 0.1 mm was used as the brazing material 21.

The carbon jig 20 into which the laminated components are inserted is placed in a hydrogen atmosphere of a heating furnace at 830 ° C. or higher.
Heated for minutes. After cooling, it was taken out of the carbon jig 20. Here, the carbon jig 20 is used for improving dimensional accuracy during brazing. Ni plating was applied to the whole of the taken-out integrated laminated structure electrode. Lapping (# 8000) was performed on both sides of the Mo portion, and the overall thickness was adjusted, flatness, and parallelism were determined. By applying Ni plating to the surface after brazing, it is possible to prevent lap abrasive grains from being contaminated on the brazed portion during lapping.

Table 1 below shows the laminated electrode according to the embodiment of the present invention manufactured as described above and the Mo electrode according to the conventional method.
Each shows the thermal characteristics of the electrodes.

[0039]

[Table 1]

As shown in Table 1 above, the laminated electrode according to the embodiment of the present invention has a slightly larger coefficient of thermal expansion than the conventional product, but within a range where there is no problem in use, and the thermal conductivity is lower. , Which is about twice as good as conventional products. Here, the thermal conductivity is affected by the size of the void at the brazing portion. Table 2 below shows the void ratio of the laminated electrode according to the embodiment of the present invention. Table 3 below shows the relationship between the void fraction and the thermal conductivity of the brazed portion.

[0041]

[Table 2]

[0042]

[Table 3]

As shown in Table 3 above, the thermal conductivity is affected by the size of the void in the brazed portion, and the void ratio in the brazed portion of the laminated electrode according to the embodiment of the present invention is 10%. But the thermal conductivity is 317.323 W / m · K
And a thermal conductivity twice that of the conventional product, and the void ratio of the laminated electrode according to the embodiment of the present invention was 6.25% at the maximum as shown in Table 2 above.

[0044]

As described above, according to the present invention, a Cu component is sandwiched between Mo components rather than an integral Mo electrode,
Since it has a brazed structure, it is possible to reduce the use of rare metal and expensive Mo, save resources, improve workability, lower overall cost and reduce the coefficient of thermal expansion only slightly. 2 without changing the thermal conductivity
It is possible to provide a laminated structure electrode that can be used as a doubled Mo electrode and a method of manufacturing the same.

According to the present invention, punching by a press machine and brazing in a furnace can be introduced, and mass production can be performed as compared with the cutting which must be performed individually used in the production of Mo electrodes. In addition, it is possible to provide a laminated structure electrode which can save processing energy and can be easily industrialized, and a method for manufacturing the same.

Further, according to the present invention, the cost can be reduced, and as a substitute for the Mo electrode which has been used only in some devices requiring high withstand voltage and high reliability until now,
A laminated electrode that can be used for general purposes can be provided.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a semiconductor device using a laminated structure electrode according to an embodiment of the present invention.

FIG. 2 is a diagram showing a laminated electrode 7 used in the semiconductor device of FIG. 1;
FIG.

FIG. 3 is a view showing a manufacturing process of the laminated electrode 7 of FIG. 2;

FIG. 4 is a view showing a manufacturing process of the laminated electrode 7 of FIG. 2;

FIG. 5 is a view showing a manufacturing process of the laminated electrode 7 of FIG. 2;

FIG. 6 is a view showing a manufacturing process of the laminated electrode 7 of FIG. 2;

FIGS. 7A and 7B are views showing a carbon jig used in a heating process of the laminated electrode 7 of FIG.

FIGS. 8A to 8D are views for explaining a method for manufacturing a Mo electrode according to a conventional method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Si chip 2 Heat compensating plate 3 Collector electrode 4 Emitter electrode 5 Teflon guide 6 Gate electrode 7 Laminated structure electrode 8a, 8b Sealing member 10 Semiconductor device 11 Mo plate 12 Mo component 13 Oxygen-free copper plate 14 Copper (Cu) component 15 Part 16, 17, 20 Carbon jig 18 Groove part 19 Hole part 21 Brazing material 51 Mo plate 52 Square plate 53 Work plate 54 Mo electrode

Claims (5)

[Claims] 1. A laminated body in which Mo layers and Cu layers are alternately laminated, wherein the laminated body has Mo layers having the same thickness at both ends in the laminating direction. An electrode having a laminated structure, which is joined by using a brazing material. 2. The laminated electrode according to claim 1, wherein
A laminated electrode, wherein at least one of the Mo layer and the Cu layer is plated with Ni. 3. The laminated electrode according to claim 1, wherein the brazing material contains Ag and Cu. 4. The laminated electrode according to claim 1, wherein the laminated electrode has a thermal conductivity of at least 300 W / m · K. 5. The flatness of the joint surface between the Mo layer and the Cu layer is 5 μm.
A method of manufacturing an electrode having a laminated structure, wherein the laminated structure is alternately laminated by brazing with a thickness of m / 10 mm or less.