Sub-nanometer-scale depth profiling of nitrogen atoms in SiO2/4H-SiC structures treated with NO annealing

Abstract

We developed a technique to probe, with sub-nanometer-scale resolution, depth profiles of nitrogen atoms in NO-treated SiO2/4H-SiC structures for Si- and C-face substrates. This technique revealed that preferential nitridation only at the SiO2/SiC interfaces proceeds in the initial stage of NO annealing. Then, for the Si-face, a longer NO treatment leads to a nitrogen distribution in SiO2 within a few nm of the interface. This result is in line with the mobility degradation in MOSFETs subjected to excessive NO annealing. For the C-face, a larger amount of nitrogen was introduced and the depth profile was unchanged after reaching a saturation level.