Impact of Post-Trench Process Treatment on Electron Scattering Mechanisms in 4H-SiC Trench MOSFETs

Abstract

This work reports the influence of post-trench treatment on electron scattering mechanisms in 4H-silicon carbide (SiC) trench MOSFETs. The mobilities representing different scattering mechanisms were extracted from the simulated transfer characteristics of devices with different post-trench Ar annealing conditions at temperatures of 0 °C–200 °C. Various mobilities, such as Coulomb mobility ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu _{\text {C}}{)}$ </tex-math></inline-formula> and surface roughness mobility ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu _{\text {SR}}{)}$ </tex-math></inline-formula> , were compared and analyzed in different samples at room temperature (RT). The result shows that accompanied by the sacrificial oxidation, Ar annealing at different temperatures and times (1500 °C and 5 min, 1500 °C and 15 min, and 1600 °C and 5 min) slightly influences Coulomb mobility but affects surface roughness mobility obviously. Further study has revealed that the Coulomb mobility is strongly related to the density of occupied interface traps, while the sidewall surface roughness gives rise to the change in surface roughness mobility.