Characterization of plasma‐deposited silicon nitride films by Auger electron spectroscopy and electron energy loss spectroscopy

摘要

Valence and core electron excitation spectra for amorphous Si nitride films prepared in a glow discharge plasma were measured by low energy electron energy loss spectroscopy (ELS). For comparision, the corresponding spectra were measured on hydrogenated amorphous silicon (a‐Si:H). The elemental composition of these films was analyzed using Auger electron spectroscopy (AES). In order to evaluate the influence of hydrogen upon the spectra, comparison of the as‐deposited plasma films was made (i) with plasma films annealed at 900 °C, (ii) with pyrolytic Si nitride, and (iii) with ion‐bombarded crystalline silicon. Significantly different ELS spectra were obtained for the plasma‐deposited films compared to the hydrogen free samples. For plasma Si nitride a new energy loss peak at 8.6 eV was detected and related to the presence of chemically bonded hydrogen. The interband excitations at high energies (EL ≳10 eV) due to Si‐N bonds were found to be less pronounced compared to chemical vapor deposited (CVD)Si nitride. For plasma silicon a new energy loss at 8.5 eV was measured which could be attributed to Si‐H bonds. The AES experiments revealed a pronounced gettering effect for impurities in plasma Si nitride.