An electron paramagnetic resonance study of defects in PECVD silicon oxides

Electron paramagnetic resonance (EPR) has been used to determine how the ty pe and population of paramagnetic defects are altered firstly by changes to the composition of oxides grown on silicon by plasma enhanced chemical vap or deposition (PECVD) and secondly by subsequent anneal treatments of the v arious oxide films. Silicon oxide films with refractive index, n, of 1.464, 1.487, 1.508 and 1.536 and thickness of 1 mum to 3 mum were studied; those of higher index have a higher silicon content. Only E' centers are detecte d in films with n=1.464 and 1.487. Raising n to 1.508 leads to the introduc tion of other types of paramagnetic centers and a large increase in the ave rage total spin concentration. Increasing n further to 1.536 produces a fur ther small increase in average spin concentration. Identities are proposed for the additional types of defect and the dependence of their population o n anneal temperature is also reported. (C) 2001 Kluwer Academic Publishers.