Humidity resistant hydrogenated carbon nitride films

The aim of this study is to prepare the hydrogenated carbon nitrides films which possess good adhesion to silicon substrates and stability in humid surroundings. The films were prepared by magnetron sputtering from pure graphite target in a nitrogen-hydrogen discharge. Two main factors can lead to delamination of the films. The first is the high value of residual stress and the second is the absorption of moisture into the bulk and their affect on films/substrates interface. Both factors were eliminated by adding hydrogen and post-deposition annealing in the vacuum. The influence of annealing (to 200, 400, 600, 800 and 1000 °C) on chemical composition and microstructure was studied by various methods. For preparation of humidity (water) resistant films we have added 15% partial pressure of hydrogen to nitrogen discharge and annealed the samples in vacuum to minimum temperature, which was 600 °C. The heating to 600 °C causes the increasing of carbon - nitride ratio from 2.0 to 2.4 and the relative atomic concentration calculated from XPS data (N 1s peak areas of CN and CN) reveals that amount of CN bonds increases from 49% to 57%. Desorption of absorbed moistures and elements from the film was studied by Thermal Desorption Spectroscopy. Dominant molecules in TDS spectra were HCN and N2, which were correlated with changes in chemical composition, measured by Rutheford Backscattering Spectroscopy and Elastic Recoil Detection Analysis. For observation of films delamination caused by high compressive stress, the Scanning Low Energy Electron Microscopy was used.