Advanced three-level converter with newly developed 1200V reverse blocking IGBTs

We developed the high voltage type modules for these renewal energy systems such as the Wind Turbine systems, Mega solar systems and “AC690V system”. The high voltage type modules are consisted of the 6th generation 1700V IGBT and FWD and 2nd generation 1200V RB-IGBT. There was a problem in the 1200V RB-IGBT for its productivity with conventional structure, because it is necessary to have long doping process time. In this time a new hybrid through-silicon isolation process was developed for 2nd generation 1200V RB-IGBT (RB-IGBT by combining wafer front-side Boron diffusion and back-side V-groove etching). Collector layer was implanted into the back-side and the surface of the V-groove, and electrically connected to the front-side Boron diffusion after activation. Thermal budget for the surface depth of Boron diffusion was thereby significantly shortened more than half for 1200V devices. This paper explains the 2nd generation 1200V RB-IGBT process flow and the experimental results of electrical characteristics. We had achieved that the power conversion efficiency of A-NPC 3-level inverter using RB-IGBTs was 98.57%, which total loss is 15% and 31% smaller than that of NPC 3-level and normal 2-level inverters, respectively.