High-temperature time-dependent dielectric breakdown of 4H-SiC MOS capacitors

-With the rapid applications of silicon carbide metal-oxide-semiconductor field-effect transistor (SiC MOSFET) power devices, further improving the performance of SiC MOSFET device through enhancing its gate oxide reliability is one of the crucial directions. The density of interface states in a SiC MOSFET is a significant parameter that affects the reliability of the gate oxide layer. In this paper, the SiC MOS capacitors (MOSCAPs) were prepared by the 1250 degrees C dry oxidation and 1350 degrees C NO annealing process. Then, we analyzed the mechanisms of the breakdown by two group of ramped experiment. And we still evaluated the reliability of oxide layer via the hightemperature time-dependent dielectric breakdown (TDDB) tests on the prepared MOSCAPs, meanwhile, the temperature effect on the reliability was considered. Furthermore, the E, 1/E, and root models with Weibull plotting were used to calculate the tBD lifetimes and failure analysis was carried on the failed samples finally. The results indicate that: (1) the impact of the generation and accumulation of the traps in the oxide, which is the main mechanisms of device failure; (2) The prediction of lifetime was calculated with three models at different acceleration factors; (3) at high-temperature, although the lower the density of interface states is, the Si epitaxial growth and C cluster will manifest in the oxide surface and lead to the breakdown of SiC MOSCAPs.