A latch-up immunized lateral trench-gate conductivity modulated power transistor

In this paper, a latch-up immunized lateral trench-gate bipolar transistor (LTGBT) is presented, along with its numerical simulations and experimental results. The current at which latch-up occurs in the structure is estimated in comparison with that of the lateral IGBT (LIGBT). The static and dynamic latch-up current densities of the LTGBT were 700 A/cm² and 640 A/cm², respectively. These results indicate an improvement of 2.3 times and 4.2 times over those for the LIGBT at the same n⁺ cathode length of 5 μm. The dependence of the latch-up current density on the design of the n⁺ and p⁺ cathode regions of the structure is also examined. The maximum controllable current density is found to increase with decreasing space between the trench gate and the p⁺ cathode. Specifically, as the space decreases to 2 μm, no latch-up phenomenon was observed in our experiment. This remarkable improvement in the latch-up performance is accomplished at the expense of an increase of 0.8 V in the threshold voltage