| 摘要 |
PROBLEM TO BE SOLVED: To provide a semiconductor device having desired trench isolation structure for securing element characteristics, and its manufacturing method. SOLUTION: The upper surface of a semiconductor substrate 1 is subjected to thermal oxidation treatment to form a gate insulation film 5. A polysilicon film that becomes a gate electrode 6 is formed on it. A mask for forming a trench is formed on the upper surface of the polysilicon film, and the semiconductor substrate 1 is etched and at the same time, the polysilicon film is etched horizontally, thus preventing the upper portion of an opening, upper end part C of the trench 2 from being covered with polysilicon. Then, the trench surface is subjected to thermal oxidation treatment, thus making the upper end part C of the opening round. |
