Annealing induced degradation of thermal SiO2: S center generation

Direct electron spin resonance evidence of profound intrinsic point defect generation in standard thermal SiO2 during postoxidation (PO) vacuum annealing is presented. The detected isotropic signal (peak-to-peak width 4.5–5.8 G; g=2.0028 at 4.3 K) is assigned to S centers, tentatively ascribed previously to E′-like defects (O3≡Si⋅ with one or two O replaced by Si). This process is advanced as atomic essence of the electrically well-known oxide degradation during PO annealing in inert ambient, likely effectuated by interface-initiated (volatile) SiO interaction. Coproduction of EX and Eδ′ defects is newly reported for thermal SiO2 as well.