SEMICONDUCTOR DEVICE AND MANUFACTURE THEREOF

摘要

PURPOSE:To control impurities at the ends of source-drain by depositing polycrystalline silicon as a diffusion source onto a thin oxide film approximately the same as a natural oxide film, diffusing impurities and removing polycrystalline silicon. CONSTITUTION:A thin oxide film 9 is formed onto the surface of a substrate and the surfaces of sidewall polycrystalline silicon 8. The film thickness is set not to disturb impurity diffusion but to provide the foundation of the machining of polycrystalline silicon. The oxide film 9 is used as the diffusion source of impurity diffusion to the substrate. Polycrystalline silicon 10 is deposited. Impurities are introduced so as to form a desired conductivity type. The polycrystalline silicon film 10 is etched while employing the extremely thin oxide film 9 as a foundation by using an anisotropic dry etching method. Accordingly, diffusion layers at the ends of source-drain can be made shallow while isolating the gate and the source-drain.