PURPOSE: To obtain a C-MOS.IC having excellent electric characteristics by forming a second conduction type first region and a first conduction type second region in impurity concentration higher than a first conduction type semiconductor substrate to the surface layer of the substrate through ion implantation and each forming MISFETs to these two regions.
CONSTITUTION: n Type ions are implanted to the surface layer section of an n-- type Si substrate 1 to form an n- layer 4, the whole surface is coated with an SiO2 film 2, and a window for shaping a well is bored to the film 2 while using a photo-resist film 3 as a mask. p Type impurity ions are implanted into the layer 4 in the window to form a p- type well region 5, the film 2 is removed, and the whole surface is coated with a thin SiO2 film 6 again. The central sections of the surfaces of the region 5 and the layer 4 adjacent to the region 5 are coated with laminates of Si3N4 films 7 and resist films 8, and p type and n type impurity ions are implanted alternately to shape a p type region 12 and an n type region 13 positioned under a selective oxide film 11 to a boundary section between the region 5 and the layer 4. Accordingly, the substrate is prepared, and FETs are each formed demarcated by the boundary section.
YASUI NORIMASA
MEGURO SATOSHI
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