PURPOSE: To obtain an electrode having high connecting reliability, by forming a thin metal film as a protecting layer for preventing oxidation, on a metal film, which is a main body of solder wetting connection, and performing mutual diffusion by heat treatment.
CONSTITUTION: On a substrate 10, the following parts are sequentially formed by evaporation by an electron beam and the like or sputtering: a Cr layer 20 of the first metal film, which is bonded to the substrate 10; a Cu layer 30 of the second metal film, which is a main body of solder wetting connection; and an Au layer 40 of the third metal film as a protecting film for preventing surface oxidation of the second metal film. Heat treatment is performed, and a mixed layer 50 is formed. An electrode pattern is formed by etching. When a flip chip is mounted on the substrate by a fused connecting method, the solder wetting property of the substrate electrode is excellently kept. Therefore, occurrence of poor connection can be reduced.
OOSHIMA MUNEO
SAKAGUCHI MASARU
SATOU RIYOUHEI
