Optimization of LIGBTs in a dielectric insulated IC-technology using a 'switched anode'

Abstract

The design of an IGBT is always a compromise between a low on state voltage drop and low switching losses. MOS-controlled emitter shorts are well known as a means to overcome this compromise but previous solutions suffer from parasitic effects and restrictions in the optimization of the high voltage part and the emitter shorting MOSFET. In this paper we propose for the first time an LIGBT where the MOSFET for shorting the p/sup +/-emitter is not merged within the high voltage structure but realized as a separated device integrated on the same chip. It is experimentally shown how with the gate voltage of the bypass MOSFET the composed device can be switched between a MOSFET mode and an IGBT mode, how by proper timing of the control voltage the turn off energy can be reduced to one third, and how it is possible to use the internal p-base/n-substrate diode of the LIGBT.