Electron spin resonance study of the interaction of hydrogen with the (111)Si/SiO2 interface: Pb-hydrogen interaction kinetics

The thermal interaction kinetics of interfacial Si dangling bond P-b defect s (Si-3 = Si) in (1 1 1)Si/SiO2, including passivation in molecular hydroge n (pictured as PbH formation) and dissociation in vacuum, is readdressed. A n initial simple thermal model had concluded simple exponential decay for b oth processes characterised by single-valued activation energies E-f and E- d, respectively. The picture, however, is found inadequate. In the first pa rt, the results are reviewed of a previous expanded electron spin resonance (ESR) study of the passivation step, leading to a consistent model for pas sivation, in which the existence of a significant spread sigma(Ef) in E-f w as exposed. In the present work, the results are presented of a similar stu dy on the dissociation kinetics, providing distinct extension of the data s et based on proper ESR defect density probing. Unlike previous conclusion, manifest non-simple exponential decay is exposed, which within the simple t hermal model reveals the existence of a distinct spread sigma(Ed) in E-d In corporation of this results in a consistent generalised thermal model, the solid set of data enabling unbiased extraction of the pertinent physical pa rameters, such as the attempt frequency k(d0) = (1.6 +/- 0.5) x 10(13) s(-1 ), close to the SI-H bending mode. The spreads in E-d and E-f are the natur al manifestation of the stress-induced non-uniformity in atomic P-b morphol ogy. The combination of both studies leads to a consistent unified picture of the P-b-(molecular) hydrogen interaction kinetics that matches underlyin g physical insight, based on the rate limiting reactions P-b + H-2 --> P-b + H and PbH --> P-b + H. It is evidenced that the model also applies to the interfacial Si dangling bond defects in (1 0 0)Si/SiO2. (C) 1999 Elsevier Science B.V. All rights reserved.