Investigation of stored energy in plasma deposited TiNx films

Abstract

Thin TiNx films were deposited using a hollow cathode arc evaporation device (HCAED) for studying the influence of low energy ion bombardment on film growth and film properties. Films were deposited at various nitrogen gas flows and negative substrate voltages and investigated by x-ray photoelectron spectroscopy (XPS) and thin film x-ray diffraction. The plasma was analyzed by Langmuir probe measurements and energy resolved mass spectrometry. From both the results of nitrogen flow experiments and the negative substrate voltage experiments it can be concluded that the ion concentration as well as the ion energy determine the film properties. The data obtained from plasma monitoring and Langmuir probe measurements were used to calculate the energy flux to the growing film in relation to the deposition parameters. XPS provides information about the chemical composition. From shifting and broadening of x-ray line profiles concentrations of interstitials, dislocation densities, and domain sizes in the films were calculated. The stored energy in the films induced by low energy ion bombardment was calculated using the energy of individual interstices and dislocations and from the fraction of atoms associated with grain boundaries. The estimation of stored energy in grain boundaries was based on a simple model concerning domain sizes and melting heat. These results were compared with investigations of the energy transfer to the substrate during the film deposition in a HCAED. The stored energy is four orders of magnitude smaller than the total ion energy flux.