Chlorine-enhanced thermal oxides growth and significant trap density reduction at SiO2/SiC interface by incorporation of phosphorus

•Thermally oxidized 4H-SiC was annealed in POCl3 ambient.•Abnormal increase of oxide thickness was observed after the annealing.•Strong dependence of traps distribution on the temperature was observed.•The increase of broken Si bonds at the interface can be expected.•Narrow temperature window of the process was confirmed.

In this article an additional annealing step was used to increase the quality of gate dielectric layers on silicon carbide obtained by thermal oxidation. The mixture of POCl3, N2 and O2 gases was used within temperature range of 950 °C–1100 °C. Abnormal oxide growth rate was observed during the annealing process. Significant improvement of trap density was achieved however the best results were obtained for lower range of annealing temperatures (950 °C–1000 °C).