Effects of the low energy-ion beam assistance in the properties of TiCxNy thin films

The stoichiometry, structure and mechanical properties of ion beam sputtered TiCxNy thin films have been studied as a function of the assistance conditions. Tuning the ratio between the current density of assisting N2+ ions and the target sputtering rate allows us to achieve films with stoichiometries in the range of 0.6>x>0.25, keeping x+y≈1. The surface topography is also sensitive to the assisting conditions where the RMS roughness is an increasing parameter as the ion beam bombardment increases. In terms of the Ar+ ion beam assistance, the films undergo a significant amorphisation and a steep increase in lattice strain as the current density and energy of the impinging ions are increased. The observed changes are discussed in terms of the energy transfer of the bombarding Ar+ ions to the layers below the surface of the growing films, leading to vacancies and defects and to a sharp decrease in film crystallinity.