Dependence of strain at the (111)Si/SiO2 interface on interfacial Si dangling-bond concentration

Thermal oxidation of Si intrinsically gives rise to the generation of defec ts at the Si/SiO2 interface as a result of mismatch induced stress. In stan dard thermal (111)Si/SiO2, the dominant paramagnetic defect observed by ele ctron spin resonance (ESR) is the P-b centre (interfacial . Si = Si-3). In the present study, the inherently incorporated as-grown P-b density ( simil ar to 4.9 x 10(12) cm(-2)) was significantly enhanced to various levels, up to 3.1 x 10(13) cm(-2), by means of the previously unveiled method for P-b creation through appropriate postoxidation annealing in H-2. This resulted , among others, in the observation of a P-b dependent anisotropic broadenin g of the ESR signal, partially arising from dipolar interaction within the essentially two-dimensional spin system. Successful quantitative simulation by a computational model has enabled detailed analysis of the line broaden ing mechanisms. The simulations reveal concentration related variations in the strain broadening contribution indicating a growing relaxation of the i nterfacial stress with increasing [P-b]. The results are discussed in the l ight of the connection between defect generation and the relaxation of stre ss. (C) 2000 Elsevier Science S.A. All rights reserved.