| 摘要 |
PURPOSE:To suppress the generation of bird's beaks to the minimum, and moreover, to eliminate the crystal defect, which is caused due to a stress to generate at the time of oxidation, by a method wherein, before the field oxide film is formed, frame-shaped withstand oxidation thin films are formed outside of the nitride films, which are the masking materials and are formed on the element regions. CONSTITUTION:An Si substrate 1 is prepared and after a thermal oxide film 2 is formed thereon, a nitride film 3 is deposited. Then, after a polycrystalline Si film 4 is deposited, a diffusion of phosphorus is performed, a patterning of resists 5 is performed and the resists 5 are selectively left. An etching is performed on the polycrystalline Si film 4 using the resists 5 as masks, and moreover, the etching is performed on the nitride film 3 as well. After the resists 5 are removed, an oxide film 6 is formed and after the oxide film on the Si substrate 1 is removed by performing a wet etching, a nitride film 7 is deposited. When an etching is anisotropically performed on the nitride film 7, the thin frame-shaped nitride films 7 are formed on the sidewalls of the nitride films 3 under the overhangs. After that, when the oxide films 6 and the poly-Si films 4 are removed, nitride film-shaped films are obtained. Then, when an oxidation is performed using the nitride films as masks, a field oxide film 8 is formed, yet the oxide film 8 obtainable at this time is one, which does not stretch to the lateral directions so much and has a sufficiently thick film thickness. |
