| 摘要 |
PROBLEM TO BE SOLVED: To provide a semiconductor device, together with its manufacturing method, where a thickness t2 of the oxide film at a drain part is larger than a thickness t1 of the oxide film at a channel region part by selecting a crystal plane exposed on a trench surface. SOLUTION: A semiconductor wafer of plane orientation (111) is prepared. A trench 26 is formed on its surface. A semiconductor layer (channel region), partitioned by the trench 26, constitutes a hexagonal unit cell pattern. Multiple unit cells are connected in parallel to constitute an MOSFETs element. A (110) surface is exposed on a semiconductor layer surface 27 on the side surface, while (111) plane is exposed on a semiconductor layer plane 28 at a bottom plane. Both silicon surfaces 27 and 28 are thermally processed at a high temperature to form a gate oxide film 29. Since growth rate differs depending on crystal plane, a film thickness t2 is formed larger than a film thickness t1.
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