Gate Oxide Instability of 4H-SiC p-Channel MOSFET Induced by AC Stress at 200 °C

The gate oxide instability of 4H-SiC pMOS induced by ac stress was experimentally investigated at 200 °C for the first time. The threshold voltage drift (<inline-formula> <tex-math notation="LaTeX">$\Delta {V}_{\text {th}}$ </tex-math></inline-formula>) of pMOS under different stress conditions was experimentally measured. The results show that high-frequency ac stress could cause the additional <inline-formula> <tex-math notation="LaTeX">$\Delta {V}_{\text {th}}$ </tex-math></inline-formula>. Furthermore, it was found first that high-frequency ac stress will cause the gate oxide breakdown at 200 °C. However, no gate oxide breakdown was found at 27 °C. By investigating the effects of ac stress conditions on the gate oxide breakdown, it is demonstrated that the captured electrons in interface states at low-level voltage (inversion) play an important role in the gate oxide breakdown.