Characterization of the Pb1 Interface Defect in Thermal (100)Si/SiO2 by Electron Spin Resonance: 29Si Hyperfine Structure and Electrical Relevance

Abstract

ABSTRACTOptimized electron spin resonance investigation resulted in the observation of the fuill angular dependence of the hyperfine (hi) spectra of the Pb1 interface defect in thermal (100)Si/SiO2, showing that the dominant hf interaction of the associated unpaired electron arises from a single Si site. The defect is identified as a prototype Si dangling bond defect with, much remarkably, the unpaired sp3-orbital pointing closely along a <211> direction at 35.26° with the [100] interface normal. If O is excluded as an immediate part of the defect, the key part of the Pb1 defect is uncovered as a tilted Si3≡Si unit. The incorporation of this defect kernel into a larger defect structure is analyzed within the framework of theoretical insight, suggesting the moiety to be part of a strained interfacial Si-Si dimer. ESR has been combined with electrical measurements to monitor the defect's behavior under thermal treatment, including postoxidation annealing in various ambients. No electrical activity of Pb1 as a detrimental interface trap could be traced, suggesting the defect to be of little relevance for device performance. The results are reviewed and discussed in the light of the defect's characteristic appearance at the (100)Si/SiO2 interface.