Negative DC bias effects on the structural, physical, and electrical properties of TiC-containing carbon films prepared by the UBMS method at low temperature

The dependence of negative DC bias voltage on the structural, and physical properties of a-C:TiC films grown by an unbalanced magnetron sputtering (UBMS) composed of two targets of carbon and titanium was investigated. From Raman and XPS analyses, the sp2 bonding fraction increased with increasing DC bias voltage. The sp2 clusters dispersed in the a-C:TiC film prepared with various negative DC bias voltages were confirmed via HRTEM and XRD analyses. The cluster distribution expanded with increasing negative DC bias voltage due to the increase of energetic ion bombardment. This is attributed to the growth of crystalline phases during sputtering deposition. As the negative DC bias voltage increased, the hardness and elastic modulus values increased with maximum values of about 29.2 GPa and 279 GPa, respectively. The COF of the a-C:TiC films slightly decreased with increasing DC bias voltage. The minimum friction coefficient of the a-C:Ti film was about 0.064. The residual stress of the films was reduced from 1.78 to 1.01 GPa with application of DC bias voltage. In addition, the resistivity and sheet resistance of a-C:Ti films decreased, as the negative DC bias voltage was increased. The a-C:Ti film prepared at −300 V DC bias voltage exhibited the lowest resistivity and sheet resistance of 9.2 × 10−4 Ω cm and 16.8 Ω/sq., respectively.