Microstructure and mechanical properties of (AlTi)_xN_1-x films by magnetic-field-enhanced high power impulse magnetron sputtering

Compared to conventional direct current magnetron sputtering, high power impulse magnetron sputtering (HiPIMS) gives rise to higher plasma activity which can be exploited to deposit films with the preferred microstructure and higher critical load, but in practice, most of the electrons are not effectively utilized and lost to the anode (chamber wall). In order to achieve higher ion flux to substrate and denser microstructure of the films, an external magnetic field is introduced. In our HiPIMS system, a coil around the magnetron target induces larger enhancement effects, and the substrate current can be increased by a factor of 2 or more if the proper current flows through the coil to intensify and confine the glow discharge. The magnetic-field-enhanced HiPIMS technology is adopted to produce (AlTi)_xN_1-x films with smooth surfaces and better mechanical properties such as surface hardness and a larger coil current produces films with lower friction. The improvement is attributed to enhanced glow discharge, more nitrogen incorporation, and intense ion bombardment.