JPS6027188B2 - Substrate for mounting semiconductor elements - Google Patents

Abstract

PURPOSE:To obtain the substrate for mounting of the semiconductor element having superior heat radiation by a method wherein a film consisting of an organic matter having the electrically insulating property and moreover having comparatively favorable thermal conductivity is coated as a thin layer on the surface of a tape of metal, alloy or composite thereof having favorable thermal conductivity. CONSTITUTION:The metal substrate 1 for mounting of the Si semiconductor element 6 and coated with the SiC thin film 4 is manufactured according to the plasma CVD method, and copper of 1.0mm. thickness and containing Zr is used for the metal substrate 1. The plasma CVD method is performed using a capacitive coupling type glow discharge device and mixed gas of 1X10<-2> Torr of SiH4 and CH4, and by heating the substrate at 500 deg.C. Accordingly the substrate 3 for mounting of the semiconductor coated with the SiC thin film 4 of 3mum thickness having favorable adhesion, having the dielectric strength characteristic of 3MV/ cm or more, having the coefficient of thermal expansion approximated to the Si element to be mounted and having superior heat radiation is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a substrate for mounting semiconductor elements that can efficiently dissipate heat generated in semiconductor elements, and can be widely applied as a component of circuit boards such as semiconductor packages and multi-chip boards. .

In recent years, with the increase in speed, density, and size of semiconductor devices,
An increase in the amount of heat generated from semiconductor elements has become a problem, and there is an increasing demand for high heat dissipation characteristics for substrates for mounting semiconductor elements. Therefore, such a substrate is required to have both high electrical insulation and high heat dissipation properties. As such a substrate, one in which an electrically insulating inorganic coating layer is formed on the surface of a highly thermally conductive metal substrate by screen printing, brazing, thermal spraying, anodic oxidation, or the like is considered.

However, no matter which method the inorganic coating layer is formed, the coating layer is porous and does not have sufficient thermal conductivity as desired. Furthermore, since it is porous, moisture in the atmosphere, conductive ions in water, etc. diffuse through the coating layer, causing deterioration of electrical insulation over time. For this reason, the coating layer needs to have a certain degree of thickness. From this point of view, there is a limit to the ability to improve thermal conductivity by making the coating layer thinner. An object of the present invention is to solve such problems by forming a dense inorganic coating layer, and to provide a substrate for mounting a semiconductor element that has excellent electrical insulation and thermal conductivity. For this purpose, the inorganic coating layer is formed by PVD or CVD.

That is, in the present invention, on the surface of a metal substrate with good thermal conductivity,
The present invention is characterized by a semiconductor element mounting substrate in which a thin coating layer made of an electrically insulating inorganic substance is formed by a PVD method or a CVD method. Since the PVD method and the CVD method are methods of forming a coating layer by colliding a coating material containing a compound with the substrate in the smallest units of substances such as ions and molecules, the particle diameter of 4 mm,
Particles precipitate.

Therefore, a dense coating layer can be obtained. Therefore, it is possible to make the coating layer thinner and improve thermal conductivity without deteriorating electrical insulation. Furthermore, PVD method and CVD method
In this method, when the coating material is collided with the substrate in the form of ions or molecules, it is possible to further improve the density by changing the nucleus growth rate relative to the nucleation rate. , conductive ions in water ~
Alternatively, metal fine particles and metal ions in the metallizing layer formed on the coating layer in a subsequent process, especially metal ions that are prone to electromigration such as silver, and particles with an ionic radius of 4 mm such as sodium and chlorine. However, even in cases where even ions become a problem, it is possible to provide a coating layer in which these do not diffuse into the coating layer.

Further, the coating layer obtained by the PVD method or the CVD method has low surface roughness and excellent adhesion to the substrate.

Therefore, when a semiconductor element is mounted on the substrate, no air gap is created between the element and the substrate, allowing for high heat dissipation from the element, and its electrical insulation is sufficiently stable even against repeated heating. are doing. Furthermore, since the coating layer is formed by a PVD method or a CVD method, the metal substrate and the inorganic material of the coating layer can be freely selected and combined in accordance with various conditions.

This is particularly effective when the substrate of the present invention is applied to a high frequency device using a Ga carrier semiconductor element. In other words, in high-frequency devices, the dielectric properties of the substrate for mounting semiconductor elements are a problem, but inorganic materials such as BN and diamond, which have a low electrolysis rate, can be used over a wide area of the substrate.
It is easy to coat uniformly and thinly. In the present invention, the metal substrate has a thermal conductivity of 0. Next al/skin/
It is preferable to use a metal plate having a temperature of sec.° C. or higher.

As a result, in combination with the characteristics of the PVD method and CVD method mentioned above, AI203 and 2Mg01Sj, which have been widely used in the past,
It has become possible to support high-speed, high-output semiconductor devices, which were not compatible with semiconductor element mounting substrates made of Akatsuki ceramics such as 02. Note that the applications of the present invention can be further expanded by using a composite metal plate whose thermal conductivity and mechanical properties can be arbitrarily changed depending on the application in place of the metal plate.

Specific metal plates and composite metal plates include Ni, Cu, and N.
Examples include various high thermal conductivity Cu alloys, copper clad stainless steel clad steel, copper clad Kovar clad steel, and Akatsuki crystals mainly composed of Mo or W. Inorganic materials used for the coating layer include BN, AI203 AI
N, SIC to S carp N Y203 2Mg0, Si02
, diamond, etc.

These inorganic substances are applied to a thickness of 1 to 10 mounds in consideration of fin air insulation and thermal conductivity. A semiconductor device assembled using the thus obtained semiconductor element mounting substrate is shown in FIG.

1' is a metal plate, and the surface thereof is coated with a coating layer 2 to form a substrate 3 for mounting a semiconductor element.

4 is a metal rising layer, 5 is an Au plating layer, and a semiconductor element 6 is mounted through these layers.

Examples will be described below.

A substrate for mounting a semiconductor element coated with an AI20 film for mounting a Si semiconductor element was fabricated using a plasma-CVD method.

A CuW alloy with a thickness of 1 was used for the metal substrate. In the plasma-CVD method, hydrogen chloride is passed through the AI chip, and the AIC
13, and at the same time, day 2, CC2 gas at 900o.
The total gas pressure was controlled to be 1.0 Tom in a reactor heated to
3.58MHZ) 300W applied, AIC13, day 2
, CO2 gas is turned into plasma, and AI2 is formed at a film formation rate of 500 to 1000 angstroms/min by gas phase reaction.
03 was coated. When the obtained AI20 porridge with a film thickness of 5 m was observed using X-ray diffraction and a scanning electron microscope, the particle size was 1.
It was found that it was Q-AI203 with a fine polycrystalline structure of less than F. m.

In addition, Ag paste was applied on the CuW alloy plate coated with the obtained AI20 mesh plate, and after firing at 900 pm,
When the dielectric strength voltage between Ag and CuW was measured, it was 500V.
Therefore, it was found that the electrical insulation properties of AI20 were good. The semiconductor element mounting substrate obtained as described above has good thermal conductivity and good heat resistance, and also has good electrical insulation properties, such as Ag, by controlling the precipitated particles of the coating layer. Even when a paste that is prone to electromigration was used as an electrode on an insulating coating layer, high insulation properties could be obtained.

As explained above, according to the present invention, a coating layer with high densities can be obtained, so that by reducing the thickness of the coating layer, thermal conductivity can be improved without deteriorating electrical insulation properties.

The substrate for mounting a semiconductor element thus obtained is capable of sufficiently responding to higher speed, higher density, and larger integrated circuits.

[Brief explanation of drawings]

FIG. 1 is a side sectional view of a semiconductor device using a semiconductor element mounting substrate of the present invention. 1: Metal plate, 2: Covering layer, 3: Semiconductor element mounting substrate,
4: Metal rising layer, 5: Au plating layer, 6: Semiconductor element. force i diagram

Claims (1)

[Claims] 1. A substrate for mounting a semiconductor device, characterized in that a thin coating layer made of an electrically insulating inorganic substance is formed on the surface of a metal substrate with good thermal conductivity by a PVD method or a CVD method.