PRODUCTION OF COPPER-CLAD ALUMINUM NITRIDE SUBSTRATE

PROBLEM TO BE SOLVED: To decrease void of interface between an aluminum nitride substrate and a copper plate and remarkably improve joining strength between the substrate and the copper plate by heating the aluminum nitride substrate at a temperature in a specific range in an oxygen- containing gas atmosphere having a dew point which is a specific temperature or below to carry out oxidation treatment of the substrate, bringing the copper plate into contact with the substrate, heating both materials at melting point or below of copper and an eutectic temperature or above of Cu-O to join the copper plate to the substrate. SOLUTION: Oxidation treatment of the substrate is carried out at 1100 to 1200 deg.C in an oxygen-containing gas atmosphere whose dew point is -25 deg.C, preferably -40 deg.C to -30 deg.C. When heat oxidation treatment of the substrate is carried out in an oxygen gas-containing atmosphere whose dew point is =1065 deg.C and