PURPOSE: To prevent side etching, by etching an electrode for bump formation and a second metal film used as a barrier metal, forming an alloy layer of a first and the second metal films by heat-treating, and then etching the first metal film.

CONSTITUTION: A first and a second metal films 4, 5 are formed on a semiconductor substrate 1. On the second metal film 5, photosensitive resin 6 is stucked. A second aperture larger than a first aperture is selectively formed, on a pad electrode 2 of the photosensitive resin 6, and the second metal film 5 is exposed. A bump 7 is formed on the second metal film 5 by plating, the photosensitive resin 6 is eliminated, the second metal film 5 is eliminated by applying the bump 7 formed by plating to a mask, and then heat-treating is performed. Further, the first metal film 4 is eliminated by applying the placed bump 7 to a mask. The first and the second metal films are alloyed by heat-treating after the second metal film 5 is subjected to etching, so that side etching can be prevented.