The Soft Punchthrough plus Superjunction Insulated Gate Bipolar Transistor: A High Speed Structure With Enhanced Electron Injection

The aim of this paper is to demonstrate the application of the superjunction (SJ) design in an insulated gate bipolar transistor (IGBT). Bipolar conduction is present and enhanced at the cathode side of the device, while the p-pillars collect the plasma deep from the anode side, thus significantly enhancing its turn-off speed. The disconnected soft punchthrough+ (SPT+) SJ IGBT is similar to the SJ IGBT, which we have previously reported, but the drift region pillars do not extend up to the cathode contact. Instead, the upper part of this device is similar to the SPT+ IGBT, i.e., it features an n+ injector around the p-well and the n-drift region that is lightly doped. The improvement in the overall performance is impressive (25% lower ON-state losses and 30% lower switching losses) and can indeed justify the technology cost associated with the SJ technology. We also demonstrate how this technology can be used to form a snapback-free reverse conducting IGBT.