JPS63124555A - Substrate for semiconductor device - Google Patents

Abstract

PURPOSE:To obtain high heat dissipating property, to make it possible to implement a low cost and a thin configuration, and to obtain excellent electric insulation, by constituting a base material by a molybdenum plate, materials comprising films of copper or copper alloy, which are provided on the upper and lower surface of the molybdenum plates, and an electric insulating ceramic thin film formed on one surface of the base material. CONSTITUTION:The base material of a substrate is formed by laminating copper or copper-alloy films 2 and 3 having high heat conductivity on the upper and lower surfaces of a molybdenum plate 1 having a small thermal expansion coefficient. As a forming method, a cladding method such as cold welding, hot welding, explosion molding and the like is suitable. An electric insulating ceramic thin film 4 is formed on one surface of said base material, e.g., on the surface of the copper or copper-alloy film 2. Thus a substrate is formed. As the electric insulating ceramic thin film 4, there are the following materials : oxides such as, e.g., Al2O3, Y2O3, ZrO2, TiO2 and the like and composite oxides, in which said oxides are the main components; nitrides of Si3N4, AlN and the like and composite nitrides, in which said nitrides are the main components; diamond-or pseudo-diamond-state carbon or the mixed material of the carbon; and the like.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electrically insulating substrate for mounting semiconductor elements and electronic/electrical components, such as a substrate for a hybrid electronic device, a substrate for an industrial computer module, and the like.

[Conventional technology]

Conventionally, alumina substrates have been widely used as such electrically insulating substrates.

However, as semiconductor devices have become larger and more highly integrated in recent years, the amount of heat generated by semiconductor devices has increased, while packages have also tended to become thinner. There is a demand for the development of excellent electrically insulating substrates.

Several types of substrates have been proposed in response to these demands, but a highly reliable electrically insulating substrate with sufficient heat dissipation properties has not yet been obtained.

For example, Fe -42% whose thermal expansion coefficient is close to that of semiconductor elements
There are substrates in which one surface of an N1 alloy or Fvar plate is coated with an electrically insulating ceramic thin film such as alumina, but these have the disadvantage of low thermal conductivity. Therefore, a substrate was proposed in which one surface of a steel or copper alloy plate with high thermal conductivity was coated with a ceramic thin film to improve heat dissipation, but the difference in thermal expansion coefficient between the ceramic and copper or copper alloy was large. Therefore, there is a drawback that the ceramic thin film is easily cracked or damaged due to thermal cycles during the coating process of the ceramic thin film or the process of mounting the semiconductor element on the tower.

Furthermore, there are substrates that use copper-tungsten or copper-molybdenum sintered alloys, which have high heat dissipation properties and have a coefficient of thermal expansion similar to that of ceramics, and whose surfaces are coated with a ceramic thin film, but they are difficult to process plastically, and , thickness 0.51), which is essential for thinning packages! Thin substrates with a thickness of 1 or less have the disadvantage of being extremely expensive.

[Problem that the invention seeks to solve]

In view of the above-mentioned conventional circumstances, the present invention provides a highly reliable semiconductor device substrate that has high heat dissipation properties, can be made thin at low cost, and has excellent electrical insulation properties. The purpose is to

[Means for solving problems]

The substrate for a semiconductor device of the present invention comprises a base material consisting of a molybdenum plate, a copper or copper alloy coating provided on both upper and lower surfaces of the molybdenum plate, and an electrically insulating ceramic thin film formed on one surface of the base material. Consisting of

The semiconductor device substrate of the present invention will be explained in detail with reference to the drawings. The base material of this board is a molybdenum plate 1 with a small coefficient of thermal expansion.
Coated with copper or copper alloy with high thermal conductivity on both upper and lower surfaces 2.3
It is a layered structure. A suitable method for forming copper or copper alloy waves on both the upper and lower surfaces of the N2.3B molybdenum plate 1 is cladding methods such as cold pressure welding, hot pressure welding, and explosion forming, but other methods may be used.

On one surface of this substrate, for example on the surface of the copper or steel alloy coating 2, is an electrically insulating ceramic thin film 4? to form a substrate. Examples of the electrically insulating ceramic thin film 4 include At 2 O, Y 2 O, and Zr0.

Oxides such as TiO□, composite oxides containing these as main components, Si3N4. Examples include nitrides such as AIN, composite nitrides containing these as main components, diamond, pseudo-diamond-like carbon, and mixtures thereof. These ceramic thin films 4 are formed by a physical or chemical vapor deposition method such as an ion blasting method or a sputtering method.

On the surface of the ceramic thin film 4 of the electrically insulating substrate of the present invention constructed as described above, metal wiring 5 is formed in a predetermined pattern by vapor deposition or the like as in the conventional method, and a semiconductor element is placed at a predetermined position on the metal wiring 5. 63 chip bonding is performed, and predetermined locations of this semiconductor element 6 and metal wiring 5 are wire-bonded using bonding wires 7 to construct a semiconductor device.

[Effect]

In the substrate of the present invention, a base material in which coatings 2.3 of copper or copper alloy with high thermal conductivity are laminated on both upper and lower surfaces of a molybdenum plate 1 with a small coefficient of thermal expansion is used, so that the heat generated in the semiconductor element 6 is It is efficiently dissipated through the copper or copper alloy coating 2.3 on the surface of the substrate. In addition, since copper or copper alloy is coated on both sides of molybdenum, it is possible not only to coat both sides with electrically insulating ceramic thin films and mount semiconductor elements on both sides of metal wiring, but also to provide high heat dissipation properties on both sides. Obtainable. At the same time, the molybdenum plate 1 reduces the coefficient of thermal expansion of the base material as a whole, and has a high melting point, so it does not soften during the mounting process, etc., and becomes a highly rigid board, allowing the board to be made thinner.

The volume fraction of the molybdenum plate 1 in the base material is 40% or more 90
% or less is preferable; if it exceeds 90%, the copper or steel alloy coating 2.3 will decrease and effective heat dissipation along the substrate surface layer will not be obtained, and if it is less than 40%, the thermal expansion coefficient of the base material will be lower than that of the semiconductor element. This is because, in addition to being unsuitable as a substrate with a temperature exceeding 1.5 times that of GaAs, the ceramic thin film 4 cracks and peels due to thermal cycling, resulting in poor reliability such as a decrease in dielectric strength voltage.

Further, a coating 2 of copper or copper alloy is applied to both the upper and lower surfaces of the molybdenum plate 1.
．． 3, it is possible to prevent the occurrence of bimetallic effects, and the base material will not be deformed even by thermal cycles received during the film formation process of the ceramic thin film 4 or the mounting process of semiconductor elements, etc., and cracks in the ceramic thin film 4 can be prevented. A highly reliable substrate can be obtained, such as by effectively preventing the occurrence of delamination and peeling. In order to exhibit this effect most effectively, it is preferable that the copper or copper alloy coatings 2 and 3 provided on both the upper and lower surfaces of the molybdenum plate 1 have the same thickness.

The thickness of the ceramic thin film 4 varies depending on the use of the substrate, but is generally preferably in the range of 1 μm to 20 μm. If the thickness is less than 1 μm, sufficient dielectric strength cannot be obtained;
This is because if it exceeds m, cracks or peeling may occur in the ceramic thin film 4 due to stress during film formation.

〔Example〕

Example I The upper and lower surfaces of a Mo plate are coated with O by a hot rolling method so that the MO volume fraction is 34 to 79%, and the thickness is 0.
25 Ou/Mo/(!U groove structure clad materials were prepared and cut into 10×301 tll pieces, respectively, and the surfaces were polished with emery paper to prepare base materials.

An AIO thin film was formed on one surface of each base material to a thickness of 0.5 to 25 μm by high frequency ion blating method to obtain a base material. In addition, the ion blasting method uses an AlO sintered body as a raw material, and while igniting it in a melting furnace with an electron beam, the oxygen pressure is increased to 2.
X 10-'torr, base material temperature 300C1) 3,5
The test was performed using a high frequency power of 100 W at 6 MHz.

As for the characteristics of each substrate, we first examined the existence of cracks in the AIO thin film using a scanning electron microscope, and then formed 310 AIN poles with a thickness of 2 μm and a 2×21B1) angle on each substrate by vacuum evaporation, and formed the gap between the electrode and the substrate. The electrical resistance was measured by applying DC SOV to the sample.

The results obtained are shown in the table below. For comparison, the thickness is 0.
A substrate (M
The characteristics of the sample (volume ratio: 0%) were similarly investigated and shown in the table below.

In samples 1 and 2 with MO volume fractions of 0% and 34%, the coefficient of thermal expansion of the entire base material was large, and cracks occurred in some parts even when the hto thin film was 1 μm thick. In addition, cracks occurred in some parts even in Black 9, where the AlO thin film was as thick as 25 μm.

Example 2 Using the black 5 base material of Example 1, a YO thin film and a 1% YO-containing ZrO thin film each having a thickness of 10 μm were formed on the surface thereof in the same manner as in Example 1.

2. The characteristics of each of the obtained substrates were examined in the same manner as in Example 1, and it was found that no cracks occurred in the ceramic thin films in any of them, and the substrates exhibited good insulation properties with an electrical resistance of 1010 Ω or more.

In the above explanation, specific examples have been explained as plates other than semiconductor elements, but the present invention is also applicable to boards other than semiconductor elements, such as for mounting between parts or components of electrical equipment or mechanical equipment, or for electrically interrupting them. It can also be applied to substrates inserted into

〔Effect of the invention〕

According to the present invention, since a copper or copper alloy coating with high thermal conductivity is laminated on the substrate surface, heat dissipation along the substrate surface is substantially reduced to that of the substrate made of copper or copper alloy. Showing excellent properties close to. In addition, molybdenum plates with a low coefficient of thermal expansion are inserted between copper or copper alloys with high thermal conductivity, so
Even if the ceramic thin film is relatively thick, it does not cause cracks, etc.
It is possible to provide a substrate for a semiconductor device that is inexpensive, can be made thinner, and has high reliability.

[Brief explanation of the drawing]

The drawing is a sectional view of a specific example of a semiconductor device using the substrate for a semiconductor device of the present invention. 1. Molybdenum plate 2.3. Copper or steel alloy coating 4.
・Ceramic thin film 5・・Metal wiring 6・・Semiconductor element
7. Bonding wire 1 group wiring ceramic thin M-type 1 same or multiple 1) overturning

Claims (4)

[Claims] (1) A semiconductor device substrate consisting of a molybdenum plate, a copper or copper alloy coating provided on both upper and lower surfaces of the molybdenum plate, and an electrically insulating ceramic thin film formed on one surface of the base material. . (2) The volume percentage of molybdenum plate in the above base material is 40%
The substrate for a semiconductor device according to claim (1), characterized in that the ratio is 90% or less. (3) The substrate for a semiconductor device according to claim (1) or (2), wherein the copper or copper alloy coatings provided on both upper and lower surfaces of the molybdenum plate have the same thickness. (4) The thickness of the electrically insulating ceramic thin film is 1 to 2
Claim (1) characterized in that the diameter is 0 μm.
A substrate for a semiconductor device according to any one of items 1 to 3.