Method for forming patterns on a semiconductor device using a lift off technique

Abstract

Upon formation of a collector electrode around a base mesa by the lift-off method, a resist film is formed over connection portions between the outer periphery of a region OAand a region in which the base mesa is formed, followed by successive formation of gold germanium, nickel and Au in this order over the entire surface of a substrate, so that the resulting stacked film will not become an isolated pattern. Thus, the stacked film over the base mesa is connected to a stacked film at the outer periphery of the region OA, facilitating peeling of the stacked film over the base mesa. Generation of side etching upon formation of a via hole extending from the back side of the substrate to a backside via electrode is reduced by forming the backside via electrode using a material which hardly reacts with an n-type GaAs layer or n-type InGaAs layer.