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

A new lateral trench insulated gate bipolar transistor (LTIGBT) with a p+ d iverter was proposed to improve the characteristics of the conventional LTI GBT. The p+ diverter layer was placed between the anode electrode and the c athode electrode. As the conventional LTIGBT has a p+ divert region, the fo rward blocking voltage was decreased significantly because the n-drift laye r corresponding to the punch-through region was reduced. However, the forwa rd 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 l ayer, the electric field moved toward the trench-oxide layer, and punch-thr ough breakdown of LTIGBT with p+ diverter occurred late. Therefore, the pdiverter of the proposed LTIGBT had no effect on the breakdown voltage unli ke the conventional LTIGBT. The latch-up current densities of the conventio nal LTIGBT and LTIGBT with a p+ diverter were 540 A/cm(2), and 1453 A/cm(2) , respectively. The enhanced latch-up capability of the proposed LTIGBT wit h a p+ diverter was obtained due to the holes in the current directly reach ing the cathode via the p+ divert region and p+ cathode layer beneath the n + cathode layer.