JPS5797675A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To suppress the elongation of a diffused region in a semiconductor device by simultaneously performing the impurity diffusion of source and drain regions and the oxidation of a gate acute part and gap part, thereby shortening the heat treating time. CONSTITUTION:An oxidized film 12 and a polycrystalline silicon film 13 are formed on a P type silicon substrate 11, a resist film 14 is formed at the gate part and with the film 14 as a mask the films 12, 13 are etched and removed. In this manner, an acute part is formed at the film 13 of the gate part, and an air gap is formed at the film 12. Subsequently, a polycrystalline silicon film 15 doped with an N type impurity is grown in vapor phase, is then heat treated in high temperature oxidative atmosphere to diffuse the impurity from the film 15, thereby forming an N<+> type layer 16 and converting the film 15 into an oxidized film 15a. Accordingly, since the acute part of the gate and the air gap part are covered with the film 15a, it can prevent the damage and improper insulation of the gate part.