Study on the Oxygen Partial Pressure Dependent Annealing Effect for SiO2/SiC Stack

Post-oxidation annealing in oxygen (O₂) ambient can improve the quality of the SiO₂/SiC stack without introducing foreign atoms. In order to reveal the annealing mechanism at different oxygen partial pressures (P(O₂)), this work focuses on the dependence of the annealing effect on P(O₂) in a wide range from 0.01 Pa to 101 kPa for SiO₂/SiC stack. In order to minimize the C-related defects generated during SiC oxidation, the SiO₂/SiC stacks are formed by oxidizing the deposited Si on the SiC epitaxial layer. The electrical characteristics of the annealed samples show that low P(O₂) is beneficial to improve the interface quality, and high P(O₂) is beneficial to improve the oxide layer quality. In addition, time of flight secondary ion mass spectrometry and X-ray photoelectron spectroscopy analysis shows that the distribution and filling of oxygen vacancies (V[O]) are consistent with the electrical results. Finally, a model describing V[O] filling amount with P(O₂) is proposed to quantitatively characterize the dependence of the annealing effect on P(O₂), which shows that the filling amount of V[O] is proportional to P(O₂)ⁿ (n∼0.065). This model provides theoretical support for improving the quality of SiC MOS by O₂ annealing.