Considerations on the kinetic correlation between SiC nitridation and etching at the 4H-SiC(0001)/SiO2 interface in N2 and N2/H2 annealing

Abstract

The kinetics of the SiC surface nitridation process of high-temperature N2 annealing was investigated with a 4H-SiC(0001)/SiO2 structure based on the correlation between the rates of N incorporation and SiC consumption induced by SiC etching. During the early stage of the annealing process, the rate-limiting step for N incorporation would be the removal of the topmost C atoms in the slow-etching case, while it would be another reaction step, probably the activation process of N, in the fast-etching case. The SiO2 layer thickness and the annealing ambient gas, which serve as the parameters affecting the SiC etching rate, would determine the N incorporation rate according to the kinetic correlation between the N incorporation and SiC etching. The SiC consumption observed during high-temperature annealing in N2 and N2/H2 atmospheres would be induced by active oxidation by residual O2 or H2O in the ambient gas, which would lead to SiC surface roughening.