| 摘要 |
PURPOSE:To form a gate oxide film on an Si substrate without decreasing a withstanding voltage by laminating an SiO2 film, a polysilicon film, and an oxidation resistant film patterned in a predetermined pattern on the substrate, oxidizing the substrate to form a field oxide film to obtain the field oxide film without bird beaks. CONSTITUTION:An SiO2 film 12 is formed by a thermal oxidation method on an Si substrate 11, a polysilicon film 13 is formed thereon by a CVD method, and a silicon nitride film 14 is sequentially laminated. After a photoresist film 15 of a predetermined pattern is then formed on the substrate, and the film 13 is etched in a predetermined pattern by anisotropic dry etching with the film 15 as a mask. The film 15 used as the mask is then removed. Subsequently, with the film 14 formed by patterning by exposing the substrate in an oxidative atmosphere as a mask the substrate 11 is oxidized together with the film 13 by a thermal oxidation method to form a field oxide film 16. Thereafter, after the film 15 is removed by hot phosphoric acid, the film 13 disposed thereunder is etched with an acid etchant, the film 12 disposed thereunder is removed by etching with hydrofluoric acid to obtain the substrate 11 formed with the film 16.
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