| 摘要 |
PROBLEM TO BE SOLVED: To prevent the problem, where at a trench IGBT, an element is broken by current concentration at turn-off with generation of high temperature and large current. SOLUTION: The interface for a trench 62 between a gate oxide film 64 and a p-base layer 56 acts as a channel, when the positive hole accumulated at an n- epitaxial layer 54 flows to an emitter electrode 72. The concentration at specific points of the positive hole through the interface breaks an element. So, a p+ isolation region 68 is so provided as to adjoin the sidewall of the trench. The p+ isolation region 68 is formed to a depth such as to partially cut into the n- epitaxial layer 54 under the p-base layer 56. The p+ separation regions 68 are provided at prescribed intervals or less in the longitudinal direction of the trench 62. Thus the interface which acts as a channel is subdivided. Since the positive hole cannot move to the interface of an adjacent p-base layer 56 across the p+ isolation region 68, the current concentrating on a specific point is limited to prevent the element from breakdown.
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