| 摘要 |
PROBLEM TO BE SOLVED: To provide a low-voltage driven trench gate MOS transistor wherein a threshold voltage required for low-voltage drive is reduced while the drop in breakdown-strength is prevented. SOLUTION: Related to the trench gate MOS transistor, a trench side wall oxide film is formed in a post process of a trench side wall after trench-etching, which is released before a gate insulating film is formed, so that an angular corner at the bottom and opening parts of a trench is changed into a curved- surface for improved breakdown-strength of the gate insulating film, while only P-base surface concentration of the trench side wall is reduced by utilizing take-in of impurities into the thick trench side wall oxide film, thus reducing the threshold voltage with no drop in breakdown-strength, etc., of an element. With the use of the trench gate structure, a low-voltage driven trench gate MOS transistor is provided with high manufacture yield with no drop in Vsus resistance nor such problem as IDSS leak current increase, etc.
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