Effect of the deposition process and substrate temperature on the microstructure defects and electrical conductivity of molybdenum thin films

The effect of point defects, dislocations and grain boundaries on the electron scattering in molybdenum thin films having a constant thickness of 500 nm was described quantitatively in form of a dependence of the electrical resistivity on the concentration of impurity atoms, stress-free lattice parameter, microstrain and grain size. The concentration of impurity atoms and the dislocation density were modified by depositing the Mo thin films using different techniques (DC magnetron sputtering, pulsed DC magnetron sputtering and RF magnetron sputtering) and by varying the substrate temperature (25 °C, 150 °C, 250 °C and 350 °C). As expected, the electrical resistivity of the Mo films decreased with decreasing density of microstructure defects. For all deposition methods, the dislocation density decreased with increasing substrate temperature, which led to an overall decrease of the measured resistivity with increasing substrate temperature. Due to the deposition equipment constraints during the RF sputtering, up to 3 at.% of Fe, Cr and Ni were incorporated at the regular lattice positions in the crystal structure of molybdenum, which increased the resistivity of the Mo films nearly two times as compared to the DC and pulsed DC sputtered films.

► Effect of impurity atoms and dislocations on the resistivity of Mo was quantified. ► Dislocation density decreased with increasing deposition temperature. ► Impurity atoms occupied both regular and interstitial lattice positions. ► Impact of impurities located at regular and interstitial positions was different.