Semiconductor device having a sense electrode

Abstract

A buried sense electrode (8) having the same structure as that of a buried gate electrode (7) is provided in an n− layer (3) of an IGBT with a sense oxide film (10) interposed therebetween. The buried sense electrode (8) senses an electric potential of the n− layer (3). If an electric potential sensed by the buried sense electrode (8) is increased to exceed a gate threshold voltage of a MOSFET (21) having an n+ drain region (22), a p well region (23) and an n+ source region (24), the MOSFET (21) is turned ON. At this time, a gate voltage applied across a gate electrode (13) and an emitter electrode (11) of the IGBT is reduced to a value obtained by a sum of an ON-state voltage of the MOSFET (21), a breakdown voltage of a Zener diode (16) having an n+ cathode region (17) and a p+ anode region (18), and a forward voltage of a diode (19) having the p+ anode region (18) and an n+ cathode region (20). As a result, various abnormalities such as overvoltage abnormalities as well as overcurrent abnormalities are detected.

Dependencies are inferred from the claim text.