[TuP3C] Power Devices

[TuP3C-13] Mitigating Trench-Corner Breakdown in High-Current-Density Vertical GaN MOSFETs

〇Yi-Chen Ho¹, Yuh-Renn Wu¹ (1. National Taiwan University (Taiwan))

We investigate the impact of the thick bottom dielectric (TBD) thickness on the performance of a vertical GaN trench MOSFET using 2D cylindrical TCAD simulations. While the reference device demonstrates a high current density of ~10 kA/cm², it suffers from premature breakdown at the trench corner. However, the introduction of an Ethylene-Octene Copolymer (EOC) or similar low-K dielectric effectively suppresses the electric field crowding, thereby mitigating this issue. By systematically varying the TBD thickness d from 0 to 700 nm, we identify a trade-off between the specific on-resistance R_on,sp, and the peak electric field in GaN and TBD layers. The optimized design with d=500nm achieves a breakdown voltage of ~500 V for 4m depletion region with a competitive specific on-resistance, balancing field relief with conduction efficiency.