Hybrid isolation process with deep diffusion and V-groove for reverse blocking IGBTs

We newly developed a 1200V Reverse Blocking (RB)-IGBT used to form bi-directional switches in advanced Neutral-Point-Clamped (A-NPC) 3-Level modules. It featured a hybrid through-silicon isolation structure combining wafer front-side boron deep diffusion with back-side V-groove etching. Collector layer was implanted into the back-side and the surface of the V-grooves, and electrically connected to the front-side boron diffusion after activation to achieve reverse-blocking capability. Thermal budget for the surface deep boron diffusion was thereby shortened more than a half of that in full diffusion case to improve both throughput and yield. Sufficient reverse blocking capability was experimentally verified.