Analytical approach of saturation voltage instability in high-speed IGBT

A High speed IGBT utilizing an Electron Beam (EB) irradiation and a post annealing process for a carrier lifetime control for a thick n-drift layer has been developed for industry applications, and home appliance especially in the very small chip size to achieve a low cost and a minimizing a size requirements. Even under the extremely high current density of around a half order of higher than the conventional usage for long-time production life, stability of both a saturation voltage V_CE(sat), on state forward voltage drop, and a turn off losses E_off are needed from a reliability point of view. We investigated dependences on the carrier lifetime control processes and a conduction current stress condition by both the IGBT electrical characteristics stability, i.e. for ward out put I-V characteristics, switching characteristics, threshold voltage, and leakage current, and a physical analysis using the Cathode Luminescence (CL) method. And we confirmed that shifts of electrical characteristics are very slight without any problem to use in the relatively high current density operation. Only for the acceleration case, an obvious CL spectrum change can be observed and to be assigned each trap level.