JPS61172355A - High-heat conductive insulating substrate - Google Patents

Abstract

PURPOSE:To enhance the thermal conductivity of the titled insulating substrate as well as to improve the high-frequency characteristics thereof by a method wherein an intermediate layer of another substrate different from silicon and alumina is provided between the silicon substrate and alumina film of the high-heat conductive insulating substrate, which is used for a high-density mounting IC and LSI and so forth. CONSTITUTION:A silicon carbide film 2 is formed on a silicon substrate 1 using silane gas or disilane gas and methane gas or ethylene gas as the vapor-phase gas, for example, according to a CVD method, and an alumina film 3 is formed on the silicon carbide film 2 using a PVD method or a CVD method. The silicon carbide film 2 exists as an intermediate layer between the silicon substrate 1 and the alumina film 3 and brings about good effect toward the improvement of adhesion of the silicon substrate 1 and the alumina film 3, and at the same time, suppresses the formation of an oxide layer at the forming time of the alumina layer 3 and works effectively for obtaining the high-heat conductivity of the high heat conductive insulating substrate. The alumina layer 3 is normally formed in an amorphous state. This alumina layer 3 has a low dielectric constant and has good high-frequency characteristics as well. By such a constitution, the insulating substrate with the sufficiently high thermal conductivity, the low dielectric constant and the superior high-frequency characteristics can be obtained at low cost.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a highly thermally conductive insulating substrate used for high-density actual devices C, LSIs, and the like.

[Background technology]

2. Description of the Related Art As semiconductor devices become more highly integrated and consume more power, dissipation of heat generated from semiconductor devices becomes an important issue. Therefore, there is a strong demand for insulating substrates with high heat dissipation properties, and various types of highly thermally conductive insulating substrates have been proposed. These include those with a multilayer structure, such as those in which an alumite layer is formed on the surface of an aluminum substrate and a resin applied thereon, and those in which a resin is directly applied to an iron or aluminum substrate. Furthermore, there are silicon carbide-beryllium oxide ceramic substrates, aluminum nitride ceramic substrates, beryllium oxide ceramic substrates, etc. However, these still have drawbacks such as insufficient thermal conductivity and high cost. There is. Therefore, an insulating substrate with even higher thermal conductivity is desired.

[Purpose of the invention]

In view of the current situation, the present invention provides an insulating substrate with high thermal conductivity.

[Disclosure of the Invention] The present invention provides an insulating substrate having a multilayer structure in which an alumina film is formed as an insulating layer on a silicon substrate,
The gist of the present invention is a highly thermally conductive insulating substrate characterized by an intermediate layer made of another material provided between a silicon substrate and an alumina film. This will be explained in detail below.

■ Prepare a silicon substrate. As a silicon substrate,
Single crystal silicon and polycrystalline silicon are commonly used.

However, the type of silicon is not particularly limited to these.

■ Form a silicon carbide film on a silicon substrate. The formation method is, for example, a CVD method using silane or disilane and methane or ethylene as gaseous gases at a formation temperature of 800 to 1000°C.

■ Form an alumina film on the silicon carbide film.

As a forming method, a PVD method or a CVD method is used.

As the PVD method, for example, Ar(80%)02(2
0%) In order to improve adhesion in the atmosphere, the substrate temperature was increased to 200%.
The temperature is maintained at about ℃, and magnetron sputtering is used using alumina as a target. Further, in the CVD method, carbon dioxide gas, hydrogen gas, and aluminum trichloride are used as gas phase gases, and the formation temperature is 800 to 1000°C. The cross-sectional shape of the formed substrate is shown in FIG.

The silicon carbide film 2 exists as an intermediate layer between the silicon substrate 1 and the alumina film 3 and is effective in improving adhesion, and is also effective in suppressing the formation of an oxide layer and obtaining high thermal conductivity when the alumina film 3 is formed. It is something that works.

Further, the alumina film 3 formed here is usually formed in an amorphous state. It has a low dielectric constant and also has good high frequency properties.

Examples will be described in detail below.

(Example 1) A silicon carbide film with a thickness of 1 w is formed on a single crystal silicon substrate with a thickness of 1 fi by a CVD method. An alumina film having a thickness of 10 IIm is formed on the silicon carbide film by the PVD method. A 3 tm x 3 tm silicon chip was mounted on this substrate and the thermal resistance value was measured (Example 2) The thermal resistance value was measured in the same manner as in Example 1 except that the thickness of the alumina film was 5 μm.

(Example 3) A 0.6 μm thick silicon carbide film and an 8 μm alumina film were formed on a polycrystalline silicon substrate with a thickness of 1 fi in the same manner as in Example 1.
The thermal resistance value was measured.

(Example 4) In the same manner as in Example 1, a silicon carbide film of 0.6 μm and an alumina film of 10 μm were deposited on a polycrystalline silicon substrate with a thickness of 0.8 μm.
The thermal resistance value was measured by forming a micrometer.

(Example 5) A silicon carbide film of 0.5 μm and an alumina film of 10 μm were formed in the same manner as in Example 1 on a polycrystalline silicon substrate with a thickness of 0.7 μm.
m was formed and the thermal resistance value was measured.

These results are shown in Table 1 together with comparative examples.

All of the examples have lower thermal resistance values than the comparative examples, indicating that the insulating substrate according to the present invention has very good thermal conductivity.

In addition, Comparative Example 1 is a 96% alumina substrate with a thickness of 1fi,
Comparative Example 2 is a 1fi thick aluminum nitride substrate, and Comparative Example 3 is a 1fi thick aluminum substrate with 10μ of resin.
The samples were coated with M, and the same measurements as in the examples were carried out on each of them.

(Margin below) [Effects of the Invention] The present invention makes it possible to obtain an insulating substrate with sufficiently high thermal conductivity, low dielectric constant, and excellent high frequency characteristics at low cost.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a highly thermally conductive substrate according to the present invention. 1... Silicon substrate 2... Silicon carbide film 3...
・Alumina membrane agent Patent attorney Takehiko Matsumoto Figure 1

Claims (2)

[Claims] (1) An insulating substrate with a multilayer structure in which an alumina film is formed as an insulating layer on a silicon substrate, with an intermediate layer made of another material between the silicon substrate and the alumina film to improve adhesion. A highly thermally conductive insulating substrate comprising: (2) The highly thermally conductive insulating substrate according to claim 1, wherein the intermediate layer is silicon carbide.