A composite structure named self-adjusted conductivity modulation SOI-LIGBT with low on-state voltage

A composite device structure on Silicon-On-Insulator (SOI) layer named Self-adjust Conductivity Modulation SOI-LIGBT (SCM-LIGBT) is proposed. It can be divided into three parts: the normal LIGBT region (NLT structure), the EM-NMOS region (ENM structure) and the diode region (DIO structure). The drain of the ENM structure is connected with the n+ emitter of the NLT structure while the p+ region in the emitter side of the NLT structure is connected to the anode of the DIO structure. The gates of the NLT structure and the ENM structure are connected together and they acted as the gate of the proposed SCM-LIGBT structure. In the on-state, the NPN parasitic bipolar structure of the NLT structure is triggered and the conductivity modulation is dramatically enhanced, which leads to the reduction on the on-state voltage. In addition, due to the base voltage of the NPN parasitic bipolar structure in the proposed device can be clamped at the forward threshold of the series diodes, therefore the latch-up issues can be immunized to guarantee the forward-biased safe-operating-area (FBSOA). The experiments demonstrate that the proposed SCM-LIGBT achieves the Vf lower than 1.18V at JA=150A/cm2.