JPS59121861A - Substrate for placing semiconductor element - Google Patents

Abstract

PURPOSE:To obtain a substrate material which has preferable thermal conductivity by covering at least part or the surface of a base metal formed of Mo or W alloy containing special amount of Cu in a thickness of the prescribed range with the film layer of the Cu or the Cu alloy containing special thermal conductivity or higher, thereby controlling the thermal expansion coefficient. CONSTITUTION:A film layer of Cu or Cu alloy having 0.03cal/cm.sec. deg.C or higher of thermal conductivity is covered on at least part of the surface of a base metal formed of W alloy containing 5-20wt% of Cu or Mo alloy containing 5-30wt% of Cu. It is in this case preferred to form a Cu or Cu alloy film layer which does not become thermal resistance with preferable soldability on the entire suface or prescribed part of the CuW, CuMo alloy surface. If the thickness if 0.5mum or less, the effect is less, and if 10.0mum or larger, the effect is saturated. If the thermal conductivity of the layer is 0.3cal/cm.sec. deg.C or less, the layer becomes a thermal resistance layer.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a substrate for mounting semiconductor elements such as integrated circuit devices, which is capable of efficiently dissipating heat generated from mounted semiconductor elements, and which is capable of efficiently dissipating heat generated by semiconductor elements mounted on the substrate. Another object of the present invention is to provide an excellent substrate for mounting a semiconductor element, which also has the property of having a coefficient of thermal expansion similar to that of other envelope materials.

As substrate materials for mounting semiconductor elements, Kovar (29%Ni-17%Co-Fe), 4.2 alloy (4 = 24Ni - Hepteramic materials such as Fe) 11, Ni alloys, alumina, and forsterite are used, and various Cu alloys have been used especially when high heat dissipation properties are required.

However, the remarkable development of the semiconductor industry in recent years has led to the increase in the size and heat generation of semiconductor elements, and the improvement of both the thermal expansion coefficient and heat dissipation properties. There is an ever-increasing need for substrate materials that are compatible.

Under these circumstances, tungsten, molybdenum, and beryllia have been proposed as materials that satisfy both of the above characteristics.

However, the latter is practically unusable due to pollution problems, and although the former two have thermal expansion coefficients that closely match those of the semiconductor element Si, there is a difference in thermal expansion coefficient from alumina, which is often used as an envelope material. GaA has a large amount of carbon dioxide, and its usage has been increasing recently for semiconductor devices.
s has a large difference in coefficient of thermal expansion, and furthermore, tungsten and molybdenum are inferior to Berria in terms of heat dissipation, and have severe restrictions on package design.

The present inventors have developed the present invention as a result of their studies in order to eliminate the above-mentioned drawbacks of conventional substrates for mounting semiconductor elements, control the coefficient of thermal expansion, and obtain a substrate material with good thermal conductivity. It is.

That is, the present invention provides a substrate for mounting a semiconductor element, which has a coefficient of thermal expansion similar to that of semiconductor elements and other envelope materials, and has excellent thermal conductivity, and which contains 5 to 2 Qwt% of Cu. 5 to 30 wt of W alloy or Cu containing
At least a part of the surface of the base metal made of MO alloy containing % CLI or thermal conductivity is Q, 3calΔ・S
Coating layer of Cu alloy of eC・°C or more is 0.5~], 0
．． This is a substrate for mounting a semiconductor element characterized by being coated with a thickness of 0 μm.

In this invention, the reason why the content of Cu in W or Mo is set to be 5 to 20.5 to 30 by weight, respectively, is due to the coefficient of thermal expansion of Sl, Ga As, and the sintering of the pond envelope material. The purpose is to approximate the coefficient of thermal expansion of crystalline alumina as much as possible, to minimize the influence of stress caused by thermal expansion mismatch, and to obtain as high thermal conductivity as possible. The difference in temperature causes cracks and damage to the semiconductor element due to a decrease in heat dissipation.

Preferably, the base metal is produced by powder metallurgy.

This is because production using the melting method is difficult due to the difference in melting point and specific gravity of Cu, W, and Mo. As the powder metallurgy method, a general-purpose powder metallurgy method may be used, and among them, a sintering method, an infiltration method, etc. are preferable.

Further, it is preferable that Cu present in W be uniformly present in W. This is to prevent variations in properties such as warping during heating, and the particle size of W powder is 0.5 to 10.0μ.
It is preferable to use a powder in the range of m.

In addition to the predetermined amount of CLI, there may be some iron group elements to form the skeleton of W and Mo, additives to improve various properties, and unavoidable impurities, but 2w
It is preferable that it is t4 or less.

In this invention, the reason why an ffl layer of copper or a copper alloy having a thermal conductivity of 0.3 cal/(yH·sec·''C or higher) is provided on the surface of the base metal is as follows.

In other words, the surface condition of base metals made of W and Mo as base materials, especially powder sintered bodies, has a large degree of roughness, and W and Mo, which form the skeleton, are inherently difficult to process even after surface polishing and other finishing treatments are applied. Therefore, it is difficult both technically and cost-wise to improve the surface roughness to the point where it can be used as a material for semiconductor substrates. On the other hand, AIJ, which is the envelope material for this substrate and Noh,
203 Stabilizing the surface condition is necessary for adhesion when bonding with lamic etc. by brazing, and when applying Al plating to improve chip bonding performance when mounting semiconductor elements on the substrate. This is a very important issue from the standpoint of reducing the amount of Fi 1 ml.

In Kono-sama f(/, ---s, it has often been attempted to provide an N coating layer on the surface of the base metal, but in N1, the thermal conductive dust itself is worse than that of the base metal.) Second, C in CuW and CuMo alloys
A CuNi alloy layer may be formed between U and U, resulting in a heat resistance layer or a strong oxide film on the surface, which may reduce adhesion. Therefore, in the present invention, the coating layer of CLI or C11 alloy which has good brazing properties and does not become a heat resistor is replaced with CuW
, the above problem was solved by providing it on the entire surface of the CuMo alloy or on a required part.

Here, the thickness of the Cu or CLI alloy limb covering layer is 05~]
0. The reason for limiting the thermal conductivity of the coating layer to Ottm is that the effect is small below 0.05 μm, and the effect is saturated below 0.0 am.
/, 671·sec·°C or more because below this, the coating layer becomes a heat resistance layer.

lr'r), if interdiffusion between the Au plating layer in the chip bonding part and Cu is a problem, CLI
It is preferable to further form a Ni coating layer as a diffusion barrier on the coating layer. In this case, since the surface condition of the base material is sufficiently improved by the underlying Cu coating layer, the thickness of the Nl layer can be reduced to 1 μm or less, which is almost negligible in terms of thermal resistance. Therefore, the thermal conductivity is clearly improved compared to the case where Ni is directly coated, which requires a thick film of at least 2 μm.

When electrical insulation is required for the above board,
By applying a thin coating of an inorganic or organic insulator to the surface of the substrate, it is also possible to use it in applications for which ceramics have traditionally been used.

Examples of inorganic insulators include BN, A-g 203. A
-eN.

S i 3N4. Y2O3,2Mg0. S i(h
, diamond, etc. or a laminate of these, and the thickness is 0.
．． 1 to 2011 m is good.

As mentioned above, by using the substrate of this invention, it is possible to handle higher density and larger semiconductor devices that will continue to increase in the future, and it can also be used as a substrate for GaAs devices, which are becoming more and more practical, in addition to Si devices. can.

This invention will be explained in detail below.

Example tungsten-0.5wt% nickel mixed powder No. 11
After stamping to size 00X100X5, 14.00
A medium sintered body having a porosity of 28 was obtained by sintering in °CH2 gas. This sintered body was infiltrated with copper using 12QQ'C in H2 gas to produce a l5Wt4CuW alloy. Thereafter, surface finishing was performed until the surface roughness was 2 μm, and a copper plating layer with a thickness of 4 μm was formed on the surface using a normal birophosphate copper plating bath.

The material thus obtained has a coefficient of thermal expansion of 6.5xl
O-6tyn/cm・°c, thermal conductivity 0.6Ca1/
/Cm・SeC・°C and other envelope material Aff
Silver brazing properties with l 203 ceramics were also extremely good.

In the same manner, 4. wt% Cu-W alloy, 6w
ttll) CLI-W alloy, ], 3 wt % Cu
-W alloy, 23wt% Cu-W alloy, 4. wt 4
Cu-Mo alloy, 5 wt% Cu-Mo alloy,
As a result of experiments on 28wtg3cu-Mo alloy and 33wt%cu-4o alloy, 6wt%, 18wt
%cu-W alloy, Q wt ratio, Q Bwt ratio C[I-M
It was confirmed that the effect of this invention can be obtained in the case of O alloy.

As described above, this invention is highly effective as a substrate for high-speed, high-density ICs, which are expected to increase further in the future.

Claims (1)

[Claims] (W alloy containing 5 to 20 wt4 of 11Cu or CI
At least a part of the surface of the base metal made of a Mo alloy containing 5 to 30W1% of Cu or a thermal conductivity of 0.3
Coating layer of Cu alloy of caI/z-5ec-'C or higher is 0
．． 5 to 10.0 ltm coated substrate for mounting a semiconductor element. (2) The substrate for mounting a semiconductor element according to claim (1), wherein the base metal is a powder sintered body.