| 摘要 |
PROBLEM TO BE SOLVED: To improve the tradeoff between the on-voltage and the turn-off loss. SOLUTION: First and second n-buffer layers 2a and 2b are formed on both sides of an n- drift layer 1, over which first and second p+ base layers 3a and 3b are formed. Further, first and second n+ emitter layers 4a and 4b are formed on the layers 3a and 3b, over which first and second main electrodes 6a and 6b are formed. First and second trenches 8a and 8b are formed which penetrate the first and second n+ emitter layers 4a and 4b as well as the first and second p+ base layers 3a and 3b, and bottoms 9a and 9b of the trenches approach the bottom within the first and second n-buffer layers 2a and 2b. Gate insulating films 7a and 7b are formed on the surface of trenches 8a and 8b, and first and second gate electrodes 5a and 5b are formed so as to fill the first and second trenches 8a and 8b.
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