| 摘要 |
PROBLEM TO BE SOLVED: To suppress a short channel effect of a threshold voltage. SOLUTION: A channel region 5, a pair of source and drain regions, and a separation insulating film 2 having a trench separation structure are selectively formed on the main surface of a semiconductor substrate 1. The groove of the upper surface of the separation insulating film 2 which adjoins the side surface of the channel region 5 is lower than the upper surface of the channel region 5, while the region other than that is almost level with the upper surface of the channel region 5. Thus, a part of a pair of side surfaces as well as the upper surface of the channel region 5 are covered with a gate electrode 4 with a gate insulating film 3 in between. A channel width W of the channel region 5 is set to twice, or less than, a maximum channel depletion layer width Xdm. The width of a groove adjoining the side surface of the channel region 5 is set to twice, or less than, the thickness of the gate electrode 4.
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