PURPOSE: To shorten the procedure of manufacturing a semiconductor device by implanting impurity ions with a substrate contact forming region as a mask, and simultaneously forming electrode contact windows in an insulating film and an oxidized film on an element forming region and a substrate contact forming region formed with source and drain diffused layers, thereby simplifying the manufacturing steps of an MOSIC.

CONSTITUTION: After a resist film 28 which has a hole 27 for selectively presenting a transistor forming region 21 is formed on a substrate, N type impurity ions of the prescribed density are selectively implanted in the region 21 with the film 28 and a gate electrode 26 as masks to form a high density As implanted region 29' on the surface of the substrate of this region. Then, the film 28 is removed, then a gate oxidized film 25 is removed, a thermal heat treatment is again performed, an oxidized film 30 is formed, and a phosphate silicate glass insulating film 31 is then formed thereon. Thereafter, the substrate is heated, and N+ type source and drain regions 29a, 29b are formed in the prescribed depth. Then, electrode contacting windows 32a, 32b, 32c and 32d are simultaneously formed by photolithographic technique.