Power semiconductor device with protective means.

摘要

In a semiconductor device where a protective Zener diode is formed through an insulation film to a silicon substrate with a power MOSFET formed, substantial breakdown strength of the insulation film is improved and withstand voltage of the Zener diode can be set large. A gate plate 111 connected electrically to an outer circumferential part of p-type diffusion region 104 is installed, and element parts 112a - 112c and equipotential plates 113a - 113c to constitute a Zener diode group 115 are formed. The equipotential plates 113a - 113c hold prescribe potential by Zener diode pairs 114 of the element parts 112a - 112c.