Properties of a-SiN x .: H films deposited at room temperature by the electron cyclotron resonance plasma method

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Abstract
A-SIN x :H films with a wide composition range (0·27≤×≤1·38), and some of them with low oxygen content, have been deposited at room temperature by the electron cyclotron resonance plasma deposition method. Auger electron spectro-scopy, infrared absorption, and transmittance and reflectance of the films in the ultraviolet/visible/near-infrared range are reported. Three different types of film are obtained: silicon rich, near stoichiometric and oxygen contaminated. At x =1·00, the hydrogen content, calculated from the infrared spectra, is a minimum (about 10 at.%), the N-H bond density becomes higher than the Si‒H density, and the slope of the Tauc plot (B) and the Urbach tail (E u), obtained from absorption coefficient results, reach minimum and maximum values, respectively. Hydrogen incorporation into the network is found to be related to that of nitrogen. A relationship between the hydrogen content and the optical properties of the films is deduced by comparing the results with those published in the literature using other plasma deposition methods. The whole set of measurements performed reveals that the properties of the films deposited at room temperature are similar to those obtained at higher temperatures by other plasma methods, and differ only in the slightly higher hydrogen content. Oxygen incorporation into the films is found to increase the structural order of the silicon nitride network, as evidenced by the decrease in E u and increase in B, even for the low oxygen content (always between 3 and 7 at.%) in the films.