| 摘要 |
PURPOSE:To form a high withstand voltage MIS semiconductor device of LOCOS structure by performing prior to the selective oxidation using a nitrided silicon film a diffusion of reverse conductive type impurity of low density in a region which contains regions of source and drain and is wider than the regions and employing as part of a mask of the diffusion of the reverse conductive type impurity of high density for forming source and drain regions the oxidized film selectively formed. CONSTITUTION:A resist film 13 is formed on an SiO2 film 12 on a P type silicon substrate 11, patterned, phosphorus ions are implanted for diffusion of low density to form N<-> type layers 14, 14, and the film 13 is subsequently exfoliated. Then, a nitrided silicon film 15 is grown by a CVD method, etched by a normal step to exfoliate the resist film. Thereafter, a field oxidized film 16 is formed by thermal oxidation. Then, the nitrided film of the regions to become source and drain is plasma etched, the resist is then exfoliated, arsenic ions are implanted with the films 15, 16 as masks, and thereafter driven in oxidative atmosphere, thereby forming a source region 18 and a drain region 19. |
