Observation of current filaments in IGBTs with thermoreflectance microscopy

In this paper, we demonstrate for the first time experimentally measured current filaments in IGBTs under repetitive Short-Circuit (SC) events. These current filaments were discovered with the help of Thermo-Reflectance Microscopy (TRM). The destruction current as function of the applied collector-emitter voltage (VCE) was determined for two differently wire-bonded 15A-1200V IGBT chips. The repetitive SC events in combination with TRM measurement indicate a wide range of non-destructive current filaments at different VCE. Similar filament formation under short-circuit conditions were observed in supporting TCAD device simulations based on multi-cell IGBT structure. These filaments have similar dimensions to the current filaments measured by TRM.