| 摘要 |
PURPOSE:To improve a sectional shape by a small area, and to isolate an element with high reliability by utilizing a plasma CVD Si3N4 film or the peculiar etching characteristics, etc. and forming an element isolation film of a rectangular sectional shape through thermal oxidation. CONSTITUTION:Phosphorus is diffused to an n type substrate through thermal diffusion technique to form a p type region 14, a thin SiO2 film is formed to the surface, and a position corresponding to a well is masked with a resist 15, and etched. When the resist is removed and the Si3N4 film 16 through plasma CVD is deposited and etched by phosphoric acid heated, an etching rate is fast extremely in a side wall section 17, the Si3N4 film of the side surface of a concave section is all removed, and only an upper surface and a lower surface remain. A SiO2 film 18 is formed to a side surface, Si therein is exposed, of the substrate through hydrogen combustion oxidation. When a SiO3N4 film is removed by phosphoric acid and n type Si is grown through an epitaxial growth method, most of the concave section are buried with a single crystal, and polycrystal Si is grown in an upper surface section. The polycrystal Si of the upper surface section is shaved through an etch-back method, the whole is flattened, the SiO2 film of the surface is removed, and the desired element isolation film by a thermal oxide film of the rectangular sectional shape can be formed. |
