A latch-up immunized lateral trench insulated gate bipolar transistor with a p+ diverter structure for smart power integrated circuit

A new lateral trench insulated gate bipolar transistor (LTIGBT) with a p+ diverter was proposed to improve the characteristics of the conventional LTIGBT. The p+ diverter layer was placed between the anode electrode and the cathode electrode. As the conventional LTIGBT has a p+ divert region, the forward blocking voltage was decreased significantly because the n-drift layer corresponding to the punch-through region was reduced. However, the forward blocking voltage of the proposed LTIGBT with a p+ diverter was about 140 V. That of the conventional LTIGBT of the same size was 105 V. Because the p+ diverter region of the proposed device was enclosed in a trench oxide layer, the electric field moved toward the trench-oxide layer, and punch-through breakdown of LTIGBT with p+ diverter occurred late. Therefore, the p+ diverter of the proposed LTIGBT had no effect on the breakdown voltage unlike the conventional LTIGBT. The latch-up current densities of the conventional LTIGBT and LTIGBT with a p+ diverter were 540 A/cm², and 1453 A/cm², respectively. The enhanced latch-up capability of the proposed LTIGBT with a p+ diverter was obtained due to the holes in the current directly reaching the cathode via the p+ divert region and p+ cathode layer beneath the n+ cathode layer.