Study of Vertical Ga₂O₃ FinFET Short Circuit Ruggedness using Robust TCAD Simulation

Abstract In this paper, the short circuit ruggedness of Gallium Oxide (Ga2O3) vertical FinFET is studied using Technology Computer-Aided-Design (TCAD) simulations. Ga2O3 is an emerging ultra-wide bandgap material and Ga2O3 vertical FinFET can achieve the normally-off operation for high voltage applications. Ga2O3 has a relatively low thermal conductivity and, thus, it is critical to explore the design space of Ga2O3 vertical FinFETs to achieve an acceptable short-circuit capability for power applications. In this study, appropriate TCAD models and parameters calibrated to experimental data are used. For the first time, the breakdown voltage simulation accuracy of Ga2O3 vertical FinFETs is studied systematically. It is found that a background carrier generation rate between 105 cm-3s-1 and 1012 cm-3s-1 is required in simulation to obtain correct results. The calibrated and robust setup is then used to study the short circuit withstand time (SCWT) of an 800V-rated Ga2O3 vertical FinFET with different inter-fin architectures. It is found that, due to the high thermal resistance in Ga2O3, to achieve an SCWT > 1μs, low gate overdrive is needed which increases Ron,sp by 66% and that Ga2O3 might melt before the occurrence of thermal runaway. These results provide important guidance for developing rugged Ga2O3 power transistors.