| 摘要 |
PURPOSE:To obviate the need of formation of side walls and to decrease a number of manufacturing processes, by patterning a polycrystalline silicon and an intermediate insulation film, isotropicaly etching the polycrystalline silicon film for creating steps between the polycrystalline silicon film and the intermediate insulation film, and implanting ions for forming a source and a drain. CONSTITUTION:A silicon substrate 51 is oxidized to from a silicon oxide film 52 serving as an intermediate insulation film. A silicon nitride film 53 and a polycrystalline silicon film 54 are deposited thereon by the CVD process. A resist film 55 is applied thereon and partially exposed to light so that is is selectively etched. Subsequently, the polycrystalline silicon film 54 and the silicon nitride film 53 are etched anisotropically and selectively in that order and the resist film 55 is removed. Further, the polycrystalline silicon film 54 is etched isotropically and selectively, whereby a structure having steps between the polycrystalline silicon film 54 and the silicon nitride film 53 is created. Then, the substrate is subjected to ion implantation and annealing. As a result, an MOS transistor having an LDD structure in which a low- concentration region 56 and a high-concentration region 57 are provided in a source and drain diffusion layer is produced.
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