Nitrogen Depth Profiling in Ultrathin Silicon Oxynitride Films with High-Resolution Rutherford Backscattering Spectroscopy

Nitrogen depth profiles in ultrathin silicon oxynitride films (2.5–8 nm) are measured by high-resolution Rutherford backscattering spectroscopy (HRBS). In order to reduce the large background due to the substrate silicon, HRBS spectra are measured under [111] channeling conditions. It is demonstrated that the HRBS/channeling technique provides the absolute concentration values and a depth resolution of sub-nm can be achieved. The nitrogen profiles are also measured by secondary ion mass spectroscopy (SIMS) and Auger electron spectroscopy (AES). The AES result roughly agrees with the HRBS result, while the SIMS result underestimates the nitrogen concentration.