The Correlations Between Physical and Electrical Properties of PECVD SiN with Their Composition Ratios

Abstract

The correlations of physical and electrical properties of PECVD films with their composition ratios (Si/N and Si‐H/N‐H) are explored and compared. The four physical properties considered include refractive index, absorption edge, mechanical stress, and density. Both refractive index and absorption edge show very similar behavior in their correlations with Si/N and Si‐H/N‐H. Their correlations with Si/N show a distinct deposition condition dependence while those with Si‐H/N‐H indicate, to within experimental error, deposition condition independence. The other two physical properties exhibit similar behavior: a parabolic dependence on Si/N with a minimum at and no correlation with Si‐H/N‐H. The two electrical properties considered are dielectric and d‐c conductivity. In the frequency range 10³–10⁶ Hz, two distinct absorption peaks are observed for films with the respective combinations of high Si‐H and low N‐H and high N‐H and low Si‐H concentrations. In d‐c conductivity, only one of the three parameters ( , , ) that characterize the Frenkel Poole conduction mechanism shows an apparent correlation with conductivity . However, σ is quantitatively demonstrated to correlate better with Si‐H/N‐H than with Si/N.