The nature and distribution of nitrogen in silicon oxynitride grown on silicon in a nitric oxide ambient

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Abstract
Ultrathin dielectrics (<4 nm) were prepared by both growing and annealing in a nitric oxide (NO) ambient, using rapid thermal processing at different temperatures for various lengths of time. Compositions and residual nitrogen contents in various dielectrics were studied using x-ray photoelectron spectroscopy (XPS). The XPS depth profiles show that the nitrogen distribution of NO grown films is different from those that are NO-annealed (an initially grown pure oxides annealed in NO), N2O-grown and N2O-annealed (an initially grown oxide annealed in N2O) oxynitrides. The nitrogen distributes evenly throughout the dielectric with an atomic percentage of around 5.4 at. % for the NO-grown sample, while the nitrogen concentration is lower at the dielectric surface and piles up at the dielectrics/silicon interface with a peak of 5 at.% for the NO-annealed oxides. Deconvolution of Si 2p and N 1s XPS spectra has been used to study the bond structures. Both Si≡N and Si-N=H2 bonds have been found in the NO-grown and NO-annealed films, the later one is believed to be introduced by hydrogen impurities present in the NO gas or growth environment.