| 摘要 |
PURPOSE:To operate a semiconductor device on the generation of a surge as a diode for protection by forming a high-concentration semiconductor layer different from a collector, a thin insulating protective film and the extending section of a base electrode. CONSTITUTION:With a power transistor, a base electrode 12 is brought to negative potential when a surge is generated on the OFF operation of switching, the electric field of the base electrode functions to a thin section 10, and a P type inversion channel layer 16 reaching to an N<+> type semiconductor layer 9 from a terminal edge section 11 in a base layer is formed in the surface 7. Consequently, a P-N<+> junction 17 is shaped by the semiconductor layer 9 and the inversion channel layer 16, and fills the role of a Zener diode for protecting the surge. When the surge is generated on the ON operation of switching of the power transistor, the P-N<+> junction 17 is formed by lowering the base electrode 12 to negative potential by a surge generation detecting circuit. Accordingly, the device is protected by the protective diode shaped by a high-concentration semiconductor layer when an external surge is generated, and switching operation is enabled and operating characteristics are not deteriorated when the surge is not generated. |
