Radiation Effects & Defects in Solids vol:158 pages:419-425
The structural degradation of thermal SiO2 on (100)Si under isochronal post oxidation vacuum annealing (POVA) has been probed by electron spin resonance (ESR). The degradation process, studied in the range T-an = 950-1250degreesC, is established as intense point defect generation including E'(gamma) E'(delta), EX and the elusive predominant degradation center S. Thermally activated generation is revealed over broad T-an ranges for the two most populous defects, S and E'(gamma), with a common activation energy similar to1.6 eV. Depth profiling after heating at 1200degreesC shows that the S centers predominantly reside near the oxide borders, generally in anticorrelation with the E. distribution. The S center susceptibility has been inferred from conventional ESR signal intensity monitoring as well as from revealed anisotropic demagnetisation effects. It is found Curie-Weiss type with critical temperature of similar to1.3 K. Newly observed weak hyperfine structure may comply with the S center being an E'-Iike defect.