Dose Dependence of the Enhancement of Thermal Oxidation for 6H-SiC by 30 keV 18O+ and 20Ne+ Irradiation

The oxidation rate of the Si-face of 6H-SiC was significantly enhanced by 30 keV 18O+ and 20Ne+ irradiation at high doses followed by thermal annealing at 1100°C in a wet oxygen atmosphere. This oxidation rate strongly depends on the ion dose. We found three regions of oxidation rate dependence on the ion dose. The three regions show the same low oxidation rate as that of the standard SiC, an oxidation rate with increased values and an oxidation rate with the fastest and saturated value. The dose dependences of the total damage obtained from Ruterford backscattering spectroscopy (RBS) measurements and of the oxide thickness are different. However, the dose dependence of the spin density determined from electron spin resonance (ESR) measurements corresponded to. The high density of dangling bonds in SiC induced by ion irradiation is considered to result in the increase of the diffusion coefficients for oxygen in SiC. Therefore, the oxidation rate of SiC is significantly enhanced. The enhanced oxidation was found to be related to the quality of the damaged layer and required higher dose than the dose necessary for amorphization, which was determined from RBS and ESR measurements.