PURPOSE: To reduce the electric resistance value of the substrate surface by specifying respectively first to third metal films to be laminated on an aluminum film.

CONSTITUTION: A first metal film 4, a second metal film 5, a third metal film 6 are successively laminated on an Al film 2 formed on a silicon substrate 1, and a bump electrode 8 is formed on the third metal film 6 by electroplating. At that time, the first metal film 4 is formed of a metal for preventing mutual diffusion of the aluminum and the bump electrode metal, the second metal film 5 is formed of a lower resistance metal than the first metal film 4 and is formed to have a larger thickness than the third metal film 6, and the third metal film 6 is formed of a metal having good adhesion with the bump electrode metal. Namely, the thick second metal film 5 having the resistance value same as or lower that of the first and the third metal films 4, 6 is formed between the third metal film 6, for preventing the mutual diffusion of the metal of the bump electrode 8 and the base Al film 2, and the first metal film 4 for strengthen the adhesion with the metal of the bump electrode 8. Thus, the bump electrode 8 with uniform thickness can be formed and the electric resistance value of the wafer surface can be reduced.