| 摘要 |
PURPOSE:To prevent the auto-doping phenomenon involving impurity travelling from source/drain regions into a channel region by a method wherein an oxide film is retained at source/drain-forming locations in the process of forming an oxide thin film for a gate. CONSTITUTION:On a P-type silicon wafer 1, a masking SiO2 film 2 is formed, covering the entire surface to serve as a mask for the diffusion of impurity. The masking SiO2 film 2 is selectively removed by etching for the formation of locations for source and drain, and then source N<+> and drain N<+> are formed by the diffusion of impurity (phosphorus). In this process, it is ensured that the oxide film will be thicker on the source N<+> and drain N<+> than on a channel forming location 3. Next, the oxide film positioned on the channel forming location 3 is totally removed by etching. The oxide film on the source and drain partially survives the etching because it is thicker there. Oxidation is accomplished for the formation of a gate oxide thin film on the channel section. |
