| 摘要 |
PROBLEM TO BE SOLVED: To solve the problem, where a Zener diode reduces an area of an actual operation region and lowers cell density, since it is formed concentrically and is thereby formed larger than a gate pad electrode in a power MOSFET where a resistor and a Zener diode are used for protecting a gate oxide film from electrostatic breakdown. SOLUTION: P-N junctions are made flat and to have the same size by alternately forming an N+ region and a P- region to a zebra form in a long and slender stripe polysilicon layer 19 embedded inside a trench 17. Thereby, a protective device of an MOSFET which can greatly reduce the area occupied by a Zener diode 2 can be realized.
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