A study of the phase transformation of low temperature deposited tantalum thin films using high power impulse magnetron sputtering and pulsed DC magnetron sputtering

Abstract

In this study, tantalum thin films were deposited on silicon substrates using high power impulse magnetron sputtering (HiPIMS) and pulsed DC magnetron sputtering (pulsed DC), investigating the texture transformation behavior of α-Ta and β-Ta tantalum films by changing the duty cycle of tantalum targets from 5% to 88% at the power of 150 W and 50 W. The surface, microstructure, and texture of sputtered tantalum films were measured by scanning electron microscopy (SEM), atomic force microscope (AFM) and X-ray diffraction spectroscopy (XRD). The hardness and resistivity were measured by nanoindentation and a four-point probe. The results reveal that the impulse power and voltage of the Ta target were increased because of the lower duty cycle. The higher the ion energy, resulting in a more efficient atomic mobility, the texture phase of tantalum film gradually changes from β-Ta-dominated to α-Ta-dominated, hardness and resistivity shift from β-Ta to the α-Ta property with the decreasing duty cycle. By adjusting the duty cycle and controlling the power, the texture transformation of tantalum film occurs. Different from the previously complicated transformation process, the tantalum thin film structure with high density and high quality deposited using this approach provides a broader range of applications.