Compositional analysis of thin SiO xN y:H films by heavy-ion ERDA, standard RBS, EDX and AES: a comparison

Abstract

The composition of silicon oxynitride (SiO x N y :H) films deposited by electron cyclotron resonance chemical vapour deposition (ECR-CVD) was analysed by ion beam techniques, heavy-ion elastic recoil detection analysis (HI-ERDA) with 150 MeV 86Kr ions and Rutherford backscattering spectroscopy (RBS) with 1.4 MeV 4He ions. The results were compared with energy dispersive X-ray analysis (EDX) and Auger electron spectroscopy (AES). Since HI-ERDA provides absolute atomic concentrations of all film components including hydrogen with a sensitivity of at least 0.005 at% the data from this method were used as a quantitative reference to assess the applicability of RBS, EDX and AES to the analysis of silicon oxynitrides. For each of these techniques the comparison with HI-ERDA allowed a discussion of the different sources of error, especially of those causing systematic deviations of the measured concentration values. A novel approach to determine from RBS spectra also the hydrogen concentrations appeared to be applicable for hydrogen levels exceeding 2 at%. Furthermore, it is shown that the film density can be determined from the HI-ERDA results alone or in combination with single-wavelength ellipsometry.