Thermally induced interface degradation in (100) and (111) Si/SiO2 analyzed by electron spin resonance

A comparative electron spin resonance (ESR) study was performed on thermal (111) Si/SiO2 and (100) Si/SiO2 of the vacuum postoxidation-induced interface degradation in terms of interfacial trivalent Si dangling bond creation (ESR-active Pb, Pb0, and Pb1 defects). In (111) Si/SiO2, the degradation mechanism was isolated as pronounced permanent Pb (∘Si≡Si3) creation from ∼640 °C onward in densities Nc monotonically increasing with anneal temperature; at ∼1100 °C, about 1.1×1013 Pbs cm−2 are created in addition to the as-oxidized state value No∼4.9×1012 cm−2. The (100) Si/SiO2 interface is found to be much less vulnerable. Only electrically harmless Pb1’s are additionally created, the density reaching Nc(Pb1)∼4.4×1012 cm−2 at ∼1100 °C. By contrast, the density of the electrically adverse Pb0 trap tends to decrease. Together with the recently established electrical irrelevance of Pb1, the results add to provide a fundamental reason for the preference of the (100) Si face in devicing.