Ionized vapor deposition of antimicrobial Ti-Cu films with controlled copper release

Formation of Ti-Cu thin films with regard to controlling the copper release is reported in the paper. Copper released from films can inhibit bacterial colonization and can be utilized as an implant surface modification. The copper release has to be controlled (i) to repress the bacteria growth and (ii) to balance the Cu level tolerated by osteoblasts cells. The dual-high power impulse magnetron sputtering superimposed with mid-frequency discharge was employed for ionized vapor deposition of Ti-Cu films. It was found that the microscopical architecture of films is strongly influenced by the pressure during the deposition process. There is an indication that these structural changes are caused by the energy of deposited species (ion distribution functions were measured by time-resolved retarding field analyzer). Grain-like structure with large Cu crystals is formed at higher pressures, i.e. at low ion energies. The grain-like microstructure increases an effective film area which encourages the copper release. It is demonstrated that controlled copper release can be achieved by appropriate setting of the input experimental parameters (pressure, mean discharge current).