Influence of pulse duration on plasma chemistry and thin film growth of plasmonic titanium nitride deposited by constant-current regulated HIPIMS

This study documents the results of an investigation into the effect of pulse duration within constant-current reactive high power impulse magnetron sputtering of titanium discharges, specifically investigating the effects on plasma chemistry and its temporal evolution and on changes to thin film texture of titanium nitride thin films produced from these discharges. Pulse durations ranging from 40 to 200 μs were studied. The data obtained from the time-resolved optical emission spectroscopy and supported by time-resolved and time-averaged mass spectrometry show three stages that can be used to characterize the generation of the discharge: gas rarefaction, pumping, and steady state. The rise in higher excitation energy species populations when increasing pulse duration provides proof of increasing electron temperature and increasing prevalence of metal ions relative to gas ions. Increasing pulse duration is shown to strongly influence film grain sizes as determined by x-ray diffraction and increase the prominence of the (200) crystal plane. The produced films are shown to exhibit instrumental nano-hardnesses within 31–35 GPa, are optically metallic, and exhibit a high localized surface plasmon resonance quality factor of 2 as obtained from the ratio between the real and imaginary dielectric permittivity. All films were produced at room temperature making the synthesis process CMOS compatible.