| 摘要 |
PURPOSE:To prevent the generation of bird's beaks by a method wherein an Si3N4 layer to be used as a mask for selective thermal oxidation is formed by ion-implanting nitrogen on the surface of a silicon substrate. CONSTITUTION:A layer 12 consisting of an SiO2 thermal oxide film is formed on one main surface 11a of a silicon substrate 11. When a photoresist mask layer 13 is formed on the layer 12 and N2 ions are implanted therein using the layer 13 as a mask, nitrogen is doped in the layer 12, silicon oxynitride is formed, and a nitride layer 14 consisting of Si3N4 silicon nitride layer is formed thereunder. Then, after an SiO2 layer 15 has been formed by performing an annealing process and a high voltage oxidation, the layers 12 and 14 are removed by etching. Subsequently, when an oxide layer 16 is removed by performing a thermal oxidation, there remains at all no N type carrier which is generated on the surface of the substrate 11 when nitrogen is formed into donor. |
