| 摘要 |
PROBLEM TO BE SOLVED: To achieve a trench type MOSFET having a high breakdown voltage. SOLUTION: A trench portion 16 the bottom of which reaches the epitaxial layer 2 is formed on the semiconductor substrate of a trench type MOSFET where a substrate 1, an epitaxial layer 2, a body part 3, and a heavily doped source portion 7 are provided adjacently in this order. A gate insulator 5 is provided on the bottom face and the sidewall face of the trench portion 16, and a gate electrode 6 is provided in the trench portion 16. Since the gate insulator 5 has a field relaxing portion 10 thicker than the gate insulator 5 between the gate electrode 6 and the body part 3, withstand voltage is enhanced in the vicinity of the bottom of the trench portion 16 and breakdown voltage can be increased. COPYRIGHT: (C)2007,JPO&INPIT
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