Hydrogen enhancement of thermally induced interface degradation in thermal (111) Si/SiO2 traced by electron spin resonance

The process of interface degradation induced in (111)Si/SiO2 by postoxidation annealing (POA) in vacuum, previously identified by electron spin resonance (ESR) as creation of persistent Pb (Si/Si3) interface defects, is found to be strongly enhanced (≈6 times) when performed in H2 ambient, and additionally, as sensed by ESR, the treshold temperature for creation is lowered from ≈640°C for vacuum to ≈550°C. It thus appears that POA in H2 rich ambient, such as routinely applied to passivate interface states (preexisting Pbs) naturally introduced during oxidation, effectively creates extra defect entities, which then have to be passivated additionally. The results point to the key role of the POA ambient in interface degradation. The data reveal the atomic nature of one of the mechanisms of the electrically long known H-induced POA generation of detrimental interface states. PACS numbers: 85.30.De; 68.35.Dv; 73.40.Ty; 76.30.Mi