Mitigating self-turn-on failures in scaled carrier stored trench IGBT: a focus on poly-Si resistivity

Scaled IGBTs improve electrical performance, but their lower gate threshold voltage (Vge(th)) results in self-turn-on issues during high dVce/dt or di/dt switching conditions. In this study, we examine a carrier stored trench bipolar transistor (CSTBT) with a split-gate design to address the self-turn-on issue in scaled IGBTs. The split-gate design, with its lower Miller capacitance, helps reduce self-turn-on. However, the issue persists when considering the resistivity of the poly-Si in the split-gates. To overcome this, we propose a selective split-gate CSTBT design that resolves self-turn-on problems, even when poly-Si resistivity is considered. TCAD simulations show that the proposed design is very effective in preventing self-turn-on and improves Vce(sat) by 24% compared to the scaled split-gate CSTBT.