| 摘要 |
PURPOSE:To prevent attachment of dust on the surface of a wafer, to avoid occurrence of defective etching and to improve a yield rate, when polysilicon on a surface part is removed, by removing an Si oxide film by wet etching so that a region in a groove remains. CONSTITUTION:An N-type epitaxial layer 12 is grown on a P-type Si wafer 11. Then a groove part is formed. An Si nitride film 13 and polysilicon films 14a and 14b are sequentially deposited by an LPCVD method. Then, the polysilicon film 14b on a surface part is oxidized by thermal oxidation, and an Si oxide film 15 is formed. When the Si oxide film 15 is removed by wet etching, an Si oxide film 16 remains in the groove. The Si oxide film 15 on the Si nitride film 13 is removed, and trench isolation is formed. Thus, a semiconductor device characterized by a high yield rate and high quality can be manufactured at a low cost.
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