Improvements in SiC MOS Processing as Revealed by Studies of Fixed and Oxide Trap Charge

Abstract

In order to improve Silicon Carbide MOSFET device performance, it is important to minimize the on-state losses by improving the effective channel mobility, which can be done by decreasing interfacial charge consisting of interface traps, fixed charge, and oxide traps, which degrade mobility due to Coulombic scattering. This paper considers a method for distinguishing between oxide traps and fixed charge, and discusses how this charge has varied with processing over the last several years. Our results show that, over the period of study, NF has trended downward. Also, the number of switching oxide traps, which gives a lower bound for Not, appears to have decreased considerably. The trends for improvement in NF and ΔNot are promising, but our data suggests that NF and Not remain much too high and need to be reduced further to realize significant gains in SiC MOSFET performance.