Method of manufacturing semiconductor device having aluminum diffused

Abstract

A method of manufacturing a semiconductor device of the type wherein aluminum layers are selectively deposited on a major surface of a silicon semiconductor substrate and thereafter aluminum is selectively diffused into the silicon semiconductor substrate by means of heat treatment. SiO.sub.2 mask is selectively formed on at least one major surface of the silicon semiconductor substrate, then aluminum is deposited onto the major surface being close to but separated from the SiO.sub.2 mask, subsequently the silicon semiconductor substrate is subjected to a heat treatment to selectively diffuse the aluminum into the silicon semiconductor substrate. The SiO.sub.2 mask which is formed before the heat treatment prevents impurity atoms from autodoping through the SiO.sub.2 mask. No cracking occurs in the SiO.sub.2 mask because the aluminum diffusion source is apart from the periphery of the SiO.sub.2 mask.