The ES-MGBT: a new fast switching MOS-gated power bipolar transistor with conductivity-modulation by a positive feedback mechanism

Abstract

A new MOS-gated device structure called the ES-MGBT is described which consists of P/sup +/ and N/sup +/ emitters, both of which are in emitter-switched configuration. In the ES-MGBT, a P/sup +/ injector coupled to the drain potential by a vertical driver DMOSFET is used to inject holes. A novel cell design is used to divert the injected holes to conductivity modulate the driver DMOSFET resulting in a low on-state voltage drop by a positive feedback mechanism. In addition, the bipolar transistor components of the device are placed in an emitter-switched configuration by the cell design which results in fast switching, high avalanche capability, and fully gate controlled characteristics. 750 V ES-MGBT devices fabricated along with DMOSFET devices on the same wafer showed 25% improvement in current density at room temperature and 36% improvement at 75/spl deg/C at a forward drop of 3.5 V. The turn-off time of the ES-MGBT was 80 ns - equal to that of the DMOSFET.