Simulation of a new lateral trench IGBT employing effective p+ diverter for improving latch-up characteristics

Abstract

A new lateral trench insulated gate bipolar transistor (LTIGBT) with p+ diverter was proposed to improve the characteristics of the conventional LTIGBT. The p+ divert layer was placed between the anode electrode and the cathode electrode. Generally, as the conventional LTIGBT had a p+ divert region, the forward blocking voltage was decreased greatly because the n-drift layer corresponding to the punch-through region was reduced. However, the forward blocking voltage of the proposed LTIGBT with p+ diverter was about 140V. That of the conventional LTIGBT of the same size was 105V. Because the p+ diverter region of the proposed device was an enclosed trench oxide layer, the electric field moved toward the trench-oxide layer, and punch through breakdown of LTIGBT with p+ diverter occurred. Therefore, the p+ diverter of the proposed LTIGBT did not relate to breakdown voltage in a way different to the conventional LTIGBT. The latch-up current densities of the conventional LTIGBT and LTIGBT with p+ diverter were 540, and 1453A/cm2, respectively. The enhanced latch-up capability of the proposed LTIGBT with p+ diverter was obtained through holes in the current directly reaching the cathode via the p+ divert region and the p+ cathode layer beneath the n+ cathode layer.