Hydrogen incorporation on CNx films deposited by ECR Chemical Vapor Deposition

Amorphous CNxHy films have been deposited by ECR-CVD from argon, nitrogen and methane gas mixtures. The composition and bonding environment of the films, consisting in one-dimensional polymeric chains with amine groups, have been studied by ERDA and IRS. By proper selection of the gas mixture composition, hydrogen incorporation in the films can be controlled. For low methane concentrations (CH4/(N2+CH4)<0.5) hydrogen atoms are predominantly joined as NHx radicals whereas for higher methane concentrations the CHx percentage in the films strongly increases. Furthermore, as the methane concentration increases, the substitution of NHx by larger size CHx radicals accounts for the decrease in the H content of the films, as detected by ERDA (Elastic Recoil Detection Analysis). The influence on the hydrogen incorporation of the argon content in the gas mixture has also been evaluated.