JPH06316707A - Metal composite parts, production thereof and semiconductor equipment - Google Patents

Abstract

PURPOSE:To provide metal composite parts excellent in heat radiating effect, furthermore, free from the generation of cracks and indentations, workable into a desired surface shape and excellent in industrial mass-productivity. CONSTITUTION:This metal composite parts have a sintered body obtd. by sintering a Cu-Mo series composite material contg. Mo as a high m.p. metal and Cu as a metal having a m.p. lower than that of Mo and a coating layer constituted of Cu, one kind of metal in the Cu-Mo series composite material and coating the surface of the sintered body. This metal composite parts show a thermal expansion coefficient close to the theoretical value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal composite part used as a substrate on which a semiconductor is mounted and a method for manufacturing the same.

[0002]

2. Description of the Related Art FIG. 3 is a sectional view showing a main part of a semiconductor package using a metal composite component of this type as a heat dissipation substrate. In FIG. 3, this semiconductor package includes a heat dissipation board 10 and a ceramic frame 3 fixed on the heat dissipation board 10.
0, the pin 40 embedded in the ceramic frame 30, and the semiconductor 20 mounted and fixed by the brazing agent 50 between the ceramic frame 30 on the heat dissipation board 10. In the fixing process of the semiconductor 20, the heat dissipation substrate 10 and the semiconductor 2 are
The wax 50 between 0 and 0 is heated to a fairly high temperature.

In the above structure, the heat dissipation substrate 10 has a high heat dissipation effect so as to cope with the heating work in the fixing process of the semiconductor 20 and the increase in the amount of heat generated by the higher density and higher output of the semiconductor integrated circuit. Things are desired. In addition to the high heat dissipation effect, the coefficient of thermal expansion of the semiconductor 20 is matched, the coefficient of thermal expansion is close to that of the package material, or the coefficient of thermal expansion is slightly different considering the matching after assembly. It is also desired.

Conventionally, Cu--Mo system or Cu has been used as a component used for a heat dissipation board satisfying the requirements concerning the coefficient of thermal expansion.
A -W metal composite part has been proposed and put to practical use. These metal composite parts are made of Cu plate and Mo plate (or W
Clad composite material made by laminating a plate) and Cu and M
It is roughly classified into a sintered body obtained by sintering a composite material with o (or Cu and W).

[0005]

By the way, in addition to the coefficient of thermal expansion, in addition to the coefficient of thermal expansion, the metal composite parts of this type are subjected to machining necessary for packaging, in particular, the portion on which the semiconductor 20 is mounted is stepped or uneven. However, it has been found that neither of the two metal composite parts is suitable for this requirement.

That is, the clad composite material is unsuitable because the composition ratio of different materials becomes uneven when the surface shape is stepped or uneven.

On the other hand, the sintered body of the composite material is preferable in that the different powders are uniformly dispersed and compounded and the various characteristics are stable, but the deformation resistance and deformability between the constituent materials constituting the composite material are high. Therefore, there is a problem that plastic workability, for example, rollability is low, production efficiency is poor, and a large material cannot be manufactured. Here, in the method of manufacturing a sintered body of a composite material, a porous sintered body of Mo (or W) is impregnated with Cu (called an infiltration method), and this sintered body is rolled to a predetermined plate thickness. Processing method, Cu powder and M
There is a method in which an o (or W) powder is mixed (called a mixing method), the mixed powder is press-molded, sintered, and then the sintered body is rolled.

However, the rolling property is low by any manufacturing method. That is, in both the infiltration method and the mixing method, when the sintered body is rolled, cracks are likely to occur perpendicularly to the rolling direction. For example, the working rate is 30% to 5%.
Rolling becomes impossible at about 0%. 50%
Even if the main part is not cracked at the stage where the above-mentioned processing has progressed, cracks (so-called edge cracks) occur at the edge parts, and a good material cannot be obtained.

[0009] Further, the sintered compact of the composite material produces a protruding Cu-Mo (W) oxide on the surface during hot rolling. This oxide produced on the surface of the sintered body adheres to the work roll, and an indentation remains on the surface of the sintered body which is the object to be rolled.
Therefore, there is a problem that the rolled sintered body has a poor finish.

An object of the present invention is to provide a metal composite part which is excellent in heat dissipation and can be processed into a desired surface shape without cracks or indentations and which is excellent in industrial mass productivity.

Another object of the present invention is to provide a plastic packaged semiconductor device which uses the above metal composite component as a heat dissipation substrate.

[0012]

According to the present invention, a sintered body obtained by sintering a composite material containing a high melting point metal and a metal having a lower melting point than the high melting point metal, and the sintered body And a coating layer made of one of the metals in the composite material covering the surface of the metal composite part.

According to the present invention, a step of sintering a composite material containing a high melting point metal and a metal having a melting point lower than that of the high melting point metal to obtain a sintered body, and the surface of the obtained sintered body are The step of packaging with a plate body made of one kind of metal in the composite material, the step of integrating the plate body with the sintered body, and the plastic working of the sintered body integrated with the plate body A method for manufacturing a metal composite component, which comprises the steps of:

That is, according to the present invention, a sintered body obtained by sintering a composite material is used as a kind of metal constituting the composite material (for example, in the case of Cu-Mo composite material: Cu or M).
By rolling at least the whole rolling surface with the plate body of o) by wrapping or the like and then rolling, a rolled plate having a composition ratio in a wide range can be easily obtained.

In the present invention, wrapping a sintered body in a plate means that the surface of the sintered body to which plastic working is applied,
For example, when a rolling process is performed, it means to dispose the plate body on at least the rolling surface (two front and back surfaces) or on the entire surface of the sintered body.

Although the thickness of the plate varies depending on the composition of the sintered body and the desired composition of the rolled plate, the thickness of the sintered body is 0.
It is preferably about 1 to 2 times. Further, the plate body on the surface of the metal composite part remains as a coating layer having a thickness of 50 to 300 μm after rolling, but the overall composition of the metal composite part may be adjusted in advance by adjusting the composition of the sintered body. Properties such as thermal conductivity can be controlled over a wide range. Moreover, since the coating layer is made of a single kind of metal, it is possible to perform plating and brazing more uniformly than the mixed layer. Furthermore, when a stepped (concave and convex) shape is processed, if a highly ductile Cu plate is used as the packaging plate, Cu can extend during processing and even cover the side surface of the stepped shape, so the characteristics are uniform. Is unchanged.

If the coating layer is not required on the surface of the metal composite part after rolling, it can be removed by lapping or the like.

Further, according to the present invention, in a semiconductor device including a heat dissipation substrate and packaged in a plastic, the heat dissipation substrate is formed by sintering a composite material containing a high melting point metal and a metal having a lower melting point than the high melting point metal. A semiconductor device is obtained which has a sintered body obtained by the above and a coating layer which covers the surface of the sintered body and which is made of one of the metals in the composite material.

Further, according to the present invention, in the heat dissipation substrate, the sintered body is one of Mo and W and Cu.
The semiconductor device is obtained by sintering a composite material including and the coating layer is made of Cu.

[0020]

The metal composite component of the present invention will be described below based on its manufacturing method.

In the present invention, a sintered body obtained by sintering a composite material containing a high melting point metal and a metal having a lower melting point than the high melting point metal by the infiltration method or the mixing method (composition: desired composition 1-5% reduction) is packaged with a plate made of one of the metals (eg, Cu) that make up the composite material. In addition, the wrapping with a plate means that the plate is arranged on at least the rolling surface of the surface of the sintered body without any gap. This packaged sintered body is heated in the range of 800 ° C. to 1000 ° C. and hot-rolled to 2 mm from the desired final plate thickness.
Finish to a thick thickness. The heating temperature is 800 ° C to 1
The range of 000 ° C is preferred. If the temperature is less than 800 ° C, the deformability is small and cracks easily occur.
This is because if the temperature exceeds 0 ° C., Cu is significantly softened or partially melted due to fluctuations in heating temperature. The obtained metal composite part hot-rolled sheet is annealed and oxides are removed, and then cold-rolled to a desired sheet thickness for finishing. The surface of the metal composite component thus obtained has a thickness of 50 μm to 300 μm.
Although it is covered with m coating layer (Cu layer), the metal composite part as a whole is a composite material having a relatively wide range of compositions. For example, the coefficient of thermal expansion and the thermal conductivity of a Cu-Mo metal composite part (thickness 1 mm) are shown in FIGS. 1 and 2, respectively.
As shown in, almost the same value as the theoretical value was obtained.

The present invention will be described in more detail below.

Example 1 By the mixing method, 39% by weight of C
The powdery composite material prepared in u-61 wt% Mo was mixed with 3
The pressed body formed at a pressure of ton / cm ² is sintered in a reducing atmosphere. The thickness of the sintered body is 8 mm, the relative density is 90
~ 98%. Then, this sintered body is packaged in an oxygen-free copper plate having a thickness of 2 mm. The packaged sintered body is heated and held at a temperature of 800 to 1000 ° C. for 15 minutes in a hydrogen atmosphere. After this, hot rolling (1
Pass) Incidentally, after the rolling step, it is not necessary to remove the projecting oxide adhering to the work roll, which is conventionally required.

Then, after heating and holding in the same atmosphere and at the same temperature for several minutes, hot rolling (second pass) is performed at the same reduction rate.
It is also possible to omit the step of removing protrusions after this. In addition, while repeating this process, cracks and ear cracks were frequently generated in the past, but this time they were not generated at all.

In this way, the hot working was completed with a thickness of about 2 mm thicker than the target plate thickness, and finally the desired plate thickness of 1 mm was finished by cold rolling.

As described above, the metal composite component according to this example was obtained. At this time, the Cu layer thickness is 100 μm, C
The u content was 40% by weight. The surface condition was also smooth and Ra was about 0.1 μm.

[Example 2] 68 wt% Cu by the mixing method
The powdery composite material prepared to -32 wt% Mo was press-molded at the same pressure as in Example 1 and then sintered in the same atmosphere. The thickness of the sintered body is 12 mm and the relative density is 90 to 98%. This sintered body was packaged in an oxygen-free copper plate having a thickness of 2 mm.

When the packaged sintered body was heated under the same conditions as in Example 1 and processed under the same rolling conditions, similar results were obtained, and a metal composite part having a plate thickness of 1 mm was obtained. .
The Cu layer had a thickness of 150 μm and the Cu content was 70% by weight. Ra was the same as in Example 1.

Example 3 41 wt% Cu by the mixing method
The powdery composite material prepared to -59 wt% Mo was press-molded at the same pressure as in Example 1 and then sintered in the same atmosphere. The thickness of the sintered body is 8 mm and the relative density is 90 to 98%. The sintered body was packaged in a Mo plate having a thickness of 0.3 mm.

When the packaged sintered body was heated under the same conditions as in Example 1 and processed under the same rolling conditions, similar results were obtained, and a metal composite part having a plate thickness of 1 mm was obtained. .
The Mo layer thickness was 50 μm, and the Cu content was 40% by weight. Ra was the same as in Example 1.

[Embodiment 4] 84 wt% Cu by the mixing method
The powdery composite material prepared to -16 wt% W was press-molded at the same pressure as in Example 1 and then sintered in the same atmosphere. The thickness of the sintered body is 4 mm and the relative density is 90 to 98%. The sintered body was packaged in a Cu plate having a thickness of 0.3 mm.

The packaged sintered body was heated under the same conditions as in Example 1 and rolled under the same conditions, and similar results were obtained, and a metal composite part having a plate thickness of 1 mm was obtained. The Cu layer thickness was 50 μm, and the Cu content was 85% by weight. Ra was the same as in Example 1.

Next, the metal composite parts obtained in Examples 1 to 4 were processed into 25 mm × 25 by a die floating method.
The plate was punched into a plate of mm and plated with Ni.
In each of the metal composite parts, punching did not cause cracks in the outer periphery and the plating could be formed evenly. Further, each of the metal composite parts was used as the heat dissipation board 10 of the semiconductor package shown in FIG. That is,
Semiconductor 20 and ceramic frame 30 on each metal composite part
Etc. were fixed and packaged to manufacture a semiconductor package. During the manufacturing process, the brazing agent 50 was heated to a considerably high temperature in order to fix the semiconductor 20.
No crack or warpage occurred in No. 10. Next, for each semiconductor package, the semiconductor 20 was heated to a temperature that assumed the actual usage state to check the compatibility with the heat dissipation board 110, but no crack or warpage occurred in each heat dissipation board 110.

According to the experiments conducted by the present inventors, the heat dissipation substrate according to the present invention can realize a coefficient of thermal expansion of 9 to 23 × 10 ⁻⁶ / K. Therefore, the heat dissipation substrate was applied to a semiconductor device packaged in a plastic package. It turned out to be effective in some cases. Hereinafter, a heat dissipation substrate used for a plastic packaged semiconductor device and a method for manufacturing the same will be described.

4 and 5 are cross-sectional views showing examples of resin inflow mold type plastic packages.

First, in the plastic package shown in FIG. 4, a heat dissipation substrate 110, a semiconductor chip 111 bonded onto the heat dissipation substrate 110, a plurality of pins 112 extending from the heat dissipation substrate 110 to the outside of the package, and a plurality of pins 112. A plurality of conducting wires 113 for electrically connecting the pin 112 and the semiconductor chip 111 and a synthetic resin 115 molded over each component are provided, and these constitute a semiconductor device.

This plastic package is manufactured by injecting and molding a synthetic resin (for example, epoxy resin or phenol resin) 115 into the heat dissipation substrate 110, the semiconductor chip 111, the plurality of pins 112, and the plurality of conducting wires 113. . However, in the plastic package shown in FIG. 4, the back surface of the heat dissipation substrate 110 is not molded and is exposed to the outside.

Next, in the plastic package in FIG. 5, the thickness of the heat dissipation board 110 is thinner than that shown in FIG. 4, and the back surface of the heat dissipation board 110 is also molded with the synthetic resin 115. It differs from the plastic package in FIG. The other parts have the same configuration as that shown in FIG.

Each of the heat dissipation boards 115 in FIGS. 4 and 5 has a rectangular plate surface.

The present invention relates to a heat dissipation board used for both types of plastic packages shown in FIGS.

Since there are various structures of the plastic packaged semiconductor devices, it is desirable to prepare heat dissipation substrates having various shapes so that they can be applied to them. Therefore, it is necessary that the heat dissipation substrate can be formed into various shapes.

6 to 8 are views showing examples of the shape of the heat dissipation board. In addition, in FIG. 6, (a) shows a plan view,
(B) shows a side view.

Heat dissipation substrates 110a, 1 shown in FIGS.
10b and 110c are both the substrate section 120,
It has an integrated stepped shape having a protrusion 121 protruding above the substrate 120. These stepped shapes are formed by the method described below. The protrusion 121 holds the semiconductor chip 11 shown in FIG. 4 or FIG. 5, and thus can be said to be a support.

More specifically, first, referring to FIG.
The heat dissipating board 10a of FIGS.
21 has a rectangular shape with four chamfered corners. The protrusion 121 also has a horizontal center line C in the drawing of the substrate 120.
1 and the center line C2 in the vertical direction in the drawing at symmetrical positions.

The heat dissipation board 10b shown in FIG. 7 has a board part 120 whose one corner is chamfered, and a rectangular projection part 121 formed on the board part 120. Protrusion 121
The position with respect to the substrate portion 120 is the same as that in FIG.

The heat dissipation board 10b of FIG. 8 has a board portion 120 whose four corners are chamfered in an arc shape, and a rectangular projection 121 formed on the board portion 120. The protrusion 121 is similar to that of FIG.
Located in the center of.

FIG. 9 is a perspective view showing still another heat dissipation board. In FIG. 9, the heat dissipation substrate 10 d includes a rectangular substrate portion 120 and a protruding portion 12 formed on the substrate portion 120.
1 and. In the heat dissipation board 10d, the protrusion 1
21 is asymmetrical with respect to the horizontal and vertical centerlines C1 and C2 in FIG. 6A. Further, the protrusion 121 is provided with a U-shaped recess 122 that opens rightward in the drawing.

The heat dissipation substrate having various shapes described above is used for a plastic packaged semiconductor device.

Hereinafter, a method of manufacturing a heat dissipation board having a stepped shape according to the present invention will be described.

[Embodiment 5] First, in the same manner as in Embodiment 2 described above, 68 wt% Cu-32 wt% Mo was mixed by the mixing method.
The powdery composite material prepared in Example 1 was press-molded at the same pressure as in Example 1 and then sintered in the same atmosphere. The thickness of the sintered body is 12 mm and the relative density is 90 to 98%. This sintered body was wrapped in an oxygen-free copper plate having a thickness of 2 mm, and heating and holding and hot rolling were repeated in the same manner as in Example 1 to give a total thickness of about 3 mm.
A packaged sintered body of was obtained.

Next, the packaged sintered body is treated at 100 ° C.
While heating and holding as described above and exposing to hot air, FIG.
Further, when a step processing (called sizing) is performed by a die having a stepped shape corresponding to the shape shown in (b), a stepped shape in which the substrate portion and the protruding portion are integrally formed is exhibited. A heat dissipation board having a total thickness of 2.5 mm was obtained.

FIG. 10 is a conceptual sectional view showing the heat dissipation board according to the obtained Example 5. Referring to FIG.
The heat dissipation substrate 130 according to the fifth embodiment includes a sintered body 131 made of Cu and Mo and having a stepped shape, and a coating layer 132 made of Cu and formed on the entire surface thereof. The coating layer 132 has a substantially constant thickness in any part of the sintered body 131. In particular,
In this example, since a Cu plate having high ductility is used as the packaging plate, even if sizing is performed, Cu is stretched during processing, and thus the rising portion of the stepped shape, that is,
It can be seen that the side surface of the protrusion is also covered.

According to the present invention, not only the shape shown in FIGS. 6A and 6B, but also any stepped shape such as the shape shown in FIGS. A coating layer made of Cu having a substantially constant thickness can be formed on all surfaces of the sintered body. That is, according to the present invention, heat dissipation boards having various shapes required for plastic packages can be obtained.

[0054]

The metal composite part according to the present invention comprises a sintered body obtained by sintering a composite material containing a high melting point metal and a metal having a lower melting point than the high melting point metal, and the surface of the sintered body. Since it has a coating layer made of one kind of metal in the composite material for covering the above, it is excellent in workability without causing cracks or edge cracks during hot rolling. Further, since no projecting oxide is generated, no oxide indentation is generated on the surface (rolled surface), which is excellent in industrial mass productivity. Specifically, the effects of the following items 1 to 3 are obtained.

The yield of good products after rolling is about 95% or more without causing cracks or edge cracks during rolling.

At the time of hot rolling, the projecting oxide attached to the work roll is not attached, and the removal step can be omitted, thus improving the productivity.

By adjusting the ratio of the mixed components of the composite material and the metal constituting the plate, for example, Cu-M
It is easy to arbitrarily set the intermediate heat characteristics of the o type.

The dispersion of Cu and Mo in the metal composite component is uniform, and there is no difference in thermal characteristics between chips having any shape by punching or cutting. Further, even if a stepped (concave / convex) shape is processed by sizing or a bending process is performed, a different material layer unlike the clad material does not occur, and the thermal characteristics of the parts do not change at all. Furthermore, cracks due to punching do not occur.

When a sufficiently densified Cu-Mo-based material is subjected to lapping to be thin,
Relatively thin finish thickness (eg 0.5-0.2mm)
You can

Further, according to the present invention, in a semiconductor device having a heat dissipation substrate and packaged in a plastic, the heat dissipation substrate is obtained by sintering a composite material containing a high melting point metal and a metal having a lower melting point. A semiconductor device having the obtained sintered body and a coating layer made of a kind of metal in a composite material for covering the surface of the sintered body is obtained. Particularly, in the heat dissipation substrate, C is used as the coating layer.
If u is used, it is possible to form a coating layer made of Cu having a substantially constant thickness on all surfaces of the sintered body regardless of the stepped shape, and various shapes required for plastic packages can be obtained. A heat dissipation board having the same can be obtained.

[Brief description of drawings]

FIG. 1 is a diagram showing a coefficient of thermal expansion with respect to a Cu content of a Cu—Mo metal composite part according to the present invention.

FIG. 2 is a diagram showing the thermal conductivity with respect to the Cu content of the Cu—Mo metal composite part according to the present invention.

FIG. 3 is a sectional view showing a main part of a semiconductor package using a metal composite component according to an example of the present invention and a conventional example.

FIG. 4 is a cross-sectional view showing an example of a molded plastic package.

FIG. 5 is a cross-sectional view showing another example of the molded plastic package.

6A and 6B are views showing a modified example of the heat dissipation board shown in FIG. 4 or 5, in which FIG. 6A is a plan view and FIG. 6B is a side view.

FIG. 7 is a plan view showing a modified example of the heat dissipation board shown in FIG. 4 or FIG.

FIG. 8 is a plan view showing a modified example of the heat dissipation board shown in FIG. 4 or FIG.

9 is a perspective view showing a modified example of the heat dissipation board shown in FIG. 4 or FIG.

FIG. 10 is a conceptual cross-sectional view showing a heat dissipation board according to a fifth embodiment of the present invention.

[Explanation of symbols]

 10 heat dissipation board 20 semiconductor 30 ceramic frame 40 pins 50 brazing agent 110 heat dissipation board 111 semiconductor chip 112 pins 113 electric wire 115 synthetic resin 120 board part 121 protruding part 130 heat dissipation board 131 sintered body 132 coating layer

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI technical display location H01L 23/373

Claims (5)

[Claims] 1. A sintered body obtained by sintering a composite material containing a refractory metal and a metal having a melting point lower than that of the refractory metal, and a metal in the composite material covering the surface of the sintered body. And a coating layer made of one of the above. 2. The metal composite component according to claim 1, wherein the sintered composite material is one of a Cu—Mo system and a Cu—W system. 3. A step of sintering a composite material containing a refractory metal and a metal having a melting point lower than that of the refractory metal to obtain a sintered body, and the surface of the sintered body thus obtained Having a step of packaging with a plate body made of one kind of metal, a step of integrating the plate body and the sintered body, and a step of plastically processing the sintered body integrated with the plate body And a method for manufacturing a metal composite part. 4. In a semiconductor device including a heat dissipation substrate and packaged in a plastic, the heat dissipation substrate is
A sintered body obtained by sintering a composite material containing a refractory metal and a metal having a melting point lower than that of the refractory metal, and a coating made of one of the metals in the composite material, which covers the surface of the sintered body. A semiconductor device having a layer. 5. In the heat dissipation substrate, the sintered body is
5. The semiconductor device according to claim 4, wherein the coating layer is obtained by sintering a composite material containing one of Mo and W and Cu, and the coating layer is made of Cu.