Abstract: A method of fabricating a semiconductor device of the type wherein aluminium layers are selectively deposited on the major surface of a silicon semiconductor substrate and thereafter aluminium is selectively diffused into the silicon semiconductor substrate by means of heat treatment in an atmosphere including an oxygen gas. Recesses are selectively formed in at least one major surface of the silicon semiconductor substrate, aluminium is deposited onto the recesses, and the silicon semiconductor substrate is then subjected to a heat treatment to selectively diffuse the aluminium into the silicon semiconductor substrate. Layers of oxide of silicon-aluminium alloy formed on the major surface subjected to the aluminium diffusion will not cause any damage of a photo-mask and at the same time accuracy in positioning the photo-mask may be improved. A failure to mount a semiconductor element onto a heat sink may also be prevented.

Abstract: A method of fabricating a semiconductor device through selective diffusion of aluminum vapor into a silicon substrate by heating a sealed tube in which the silicon substrate and an aluminum source are disposed. The diffusion is effected with a low concentration of aluminum smaller than about 10.sup.17 atoms/cm.sup.3, thereby making it possible to use a silicon oxide film as a diffusion mask for the selective diffusion of aluminum at predetermined region of the silicon substrate.

Abstract: An aluminum diffusion source layer is formed by vacuum evaporation on a major surface of a silicon substrate. The silicon substrate is heated to form an aluminum-silicon alloy layer, an aluminum doped silicon recrystallization layer and an aluminum diffusion layer. Thereafter, the aluminum-silicon alloy layer is removed from the major surface of the silicon substrate. Drive-in diffusion is performed so as to diffuse, aluminum included in the silicon recrystallization layer and the aluminum diffusion layer, into the silicon substrate. As a result, the aluminum diffusion concentration of 10.sup.16 -10.sup.19 atoms/cm.sup.3 can be obtained.