Variation of carbon concentration, ion energy, and ion current density of magnetron-sputtered boron carbonitride films

Diamond, cubic boron nitride and also ternary materials consisting of boron , carbon and nitrogen exhibit an extraordinary combination of extreme mecha nical and physical properties due to their bonding characteristics and crys tal structure. This results in a high application potential in protective a nd functional layers. Taking into account the special properties of these p hases, the compositions inside the B-C-N concentration triangle are of part icular interest, as novel superhard phases are expected to occur. In this w ork, boron carbonitride films of variable compositions were produced by mea ns of reactive radio frequency (r.f.) magnetron sputtering in combination w ith ion bombardment. Examination up to now has revealed carbon concentratio ns between 16 and 27 at.% and a boron/nitrogen ratio varying between 1.08 a nd 1.26. For a carbon concentration of 12 at.%, the ion energy was varied b etween 125 and 300 eV at a constant ratio of ions to film-forming particles , Phi(ion)/Phi(BCN). Peak analyses of the differentiated Auger spectra gave no indication of any generation of B-C bonds. The contents of the h-BN pha se and c-BN phase as well as the threshold conditions and optimum condition s for c-BN formation were investigated for 8 energy variations at 18 values of Phi(ion)/Phi(BCN) between 0.1 and 0.5. IR spectroscopy showed that the maximum fraction of sp(3)-hybrid BN bonds reached approximately 61% at an i on energy of 200 eV and an ion current density of 0.5 mA cm(-2). The film p roperties can be strongly influenced by the flux ratio of ions to film-form ing particles, Phi(ion)/Phi(BCN), and by the ion energy. Generally, the eff ect on the film properties by increasing the flux ratio Phi(ion)/Phi(BCN) o r by decreasing the ion energy is often the same. This statement is discuss ed theoretically. (C) 1999 Published by Elsevier Science S.A. All rights re served.