Identification of a New Defect in Silicon Nitride Films

When silicon nitride films are prepared at a high deposition rate, a complicated ESR spectrum appears, which cannot be attributed to Si dangling bonds or N dangling bonds. It is found by the substitution of 14N with 15N that the hyperfine interaction with nitrogen nuclei is the origin of the complicated ESR spectrum. With comparison of the observed ESR spectra with the results of a computer simulation and a first-principles calculation, the new defect is designated as a pure p-type unpaired spin strongly localized on two inequivalent nitrogen atoms bonded to each other. Furthermore, we have also observed the change in the ESR spectra originating from the N-pair defect, the N dangling bond and the Si dangling bond in the 14N and 15N samples with ultraviolet soaking after high-temperature annealing.