Microstructure and residual stress dependence of molybdenum films on DC magnetron sputtering conditions

In this work, the effects of the DC sputter conditions on the microstructure, morphology, topography, and adhesion of molybdenum (Mo) thin films deposited over graphite were analyzed. The sputtering power was varied in the 100-400 W range. Likewise, the working gas pressure was varied in the 1-4 Pa range. Different analytical techniques i.e., scanning electron microscopy (SEM), X-ray diffraction (XRD), atomic force microscopy (AFM) and Hall's effect were employed for characterizing the Mo/graphite coupons. The crystallite size was found to increase with the increase in the deposition rate as a result of the increase in the sputter power. The residual stresses in the films shift from compressive to tensile with increasing the working gas pressure. Similarly, the surface roughness was also found to increase with the increase in the working gas pressure. Moreover, all Mo thin films showed excellent adhesion as no delamination in any film was observed after adhesion test. Our findings suggest that the high-quality Mo film with dense pack structure and high crystallinity was achieved at moderate working gas pressure and high sputtering powers.