Susbstrate material for mounting a semiconductor device, substrate for mounting a semiconductor device, semiconductor device, and method of producing the same
To provide a substrate material made of an aluminum/silicon carbide composite alloy which has a thermal conductivity of 100 W/m×K or higher and a thermal expansion coefficient of 20×10 −6 /° C. or lower and is lightweight and compositionally homogeneous. A substrate material made of an aluminum/silicon carbide composite ally which comprises Al—SiC alloy composition parts and non alloy composition part and dispersed therein from 10 to 70% by weight silicon carbide particles, and in which the fluctuations of silicon carbide concentration in the Al—SiC alloy composition parts therein are within 1% by weight. The substrate material is produced by sintering a compact of an aluminum/silicon carbide starting powder at a temperature not lower than 600° C. in a non-oxidizing atmosphere.
1. A method of producing a substrate made of an aluminum/silicon carbide composite alloy by the sintering method, comprising the steps of:
mixing an aluminum powder and silicon carbide powder to form an aluminum/silicon carbide starting powder having a silicon carbide content of from 10 to 70% by weight;
compacting the aluminum/silicon carbide starting powder to form a compact;
sintering the compact at a temperature of 600° C. or higher in a non-oxidizing atmosphere for aluminum to thereby obtain a pre-formed substrate made of an aluminum/silicon carbide composite alloy; and
forming a coating layer on a surface of the pre-formed substrate to thereby obtain the substrate.
2. The method of producing a substrate as claimed in claim 1 , wherein the step of forming a coating layer is:
heating the substrate in an oxidizing atmosphere; or exposing the substrate to a steam atmosphere.
3. The method of producing a substrate as claimed in claim 1 , wherein the step of forming a coating layer comprises steps of:
forming a layer of a metal having a Young's modulus of 15,000 kg/mm 2 or lower on the substrate material;
polishing the metal layer;
and plating the polished metal layer with at least one metal selected from nickel and gold.
4. The method of producing a substrate as claimed in claim 1 , wherein the step of forming a coating layer comprises steps of:
forming a layer of a metal having a melting point of 600° C. or lower on the substrate surface;
heating the metal layer to a temperature not higher than 600° C.; and plating the metal layer with at least one metal selected from nickel and gold.
5. The method of producing a substrate as claimed in claim 1 , wherein the step of forming a coating layer comprises steps of:
forming a layer of at least one organic resin selected from an epoxy resin, a silicone resin, a polyimide resin, and the like each containing a metallic filler or not on the substrate surface.
6. The method of producing a substrate as claimed in claim 5 , wherein the step of forming a coating layer further comprises steps of:
plating a metal layer made of at least one metal selected from nickel and gold on the layer of organic resin.
7. The method of producing a substrate as claimed in claim 6 , wherein the forming step of a layer of a metal having a Young's modulus of 15,000 kg/mm 2 or lower on the substrate is conducted by barrel plating.
8. The method of producing a substrate as claimed in claim 7 , wherein the barrel plating is conducted in a container which contains metal spheres having a particle diameter of from 0.1 to 10 mm and having the same composition as the deposit to be formed.
9. The method of producing a substrate as claimed in claim 8 , wherein the spheres contained in the container for use in barrel plating have a surface area which is at least two times that of the corresponding true spheres.