Growth of HfN thin films by reactive high power impulse magnetron sputtering

Abstract

Thin hafnium nitride films were grown on SiO2 by reactive high power impulse magnetron sputtering (HiPIMS) and reactive direct current magnetron sputtering (dcMS). The conditions during growth were kept similar and the film properties were compared as growth temperature, nitrogen flow rate, and in the case of HiPIMS, duty cycle were independently varied. The films were characterized with grazing incidence X-ray diffraction (GIXRD), X-ray reflection (XRR) and X-ray stress analysis (XSA). HiPIMS growth had a lower growth rate for all grown films, but the films surfaces were smoother. The film density of HiPIMS deposited films grown at low duty cycle was comparable to dcMS grown films. Increasing the duty cycle increased the density of the HiPIMS grown films almost to the bulk density of HfN as well as increasing the growth rate, while the surface roughness did not change significantly. The HiPIMS grown films had large compressive stress while the dcMS grown films had some tensile stress. The dcMS grown films exhibit larger grains than HiPIMS grown films. The grain size of HiPIMS grown films decreases with increasing nitrogen flow rate, while the dcMS grain size increased with increasing nitrogen flow rate. This work shows that duty cycle during HiPIMS growth of HfN films has a significant effect on the film density and growth rate while other film properties seem mostly unaffected.