Influence of the substrate bias on the stress in Ti-DLC films deposited by dc magnetron sputtering

Internal stress of titanium-diamond like carbon (Ti-DLC) films deposited by reactive sputter deposition from a titanium target in argon/acetylene atmosphere have been studied as a function of the substrate bias voltage from 0 to -80 V. The Ti-DLC films were deposited using a DC current of 150 mA and substrate temperature of as-deposited. The films were characterized by Raman spectroscopy, Auger electron spectroscopy (AES), scanning electron microscopy (SEM) and wafer curvature for stress determination. It has been observed that the compressive stress increases with increasing the substrate bias. From AES the titanium content increases with the substrate bias whereas the carbon content decreases. Raman spectroscopy indicates that line spectra and the ratios ID/IG changes for bias voltages higher than -50 V. Based on the results, it is concluded that the variation in compressive stress is associated to changes in the chemistry and internal structure of the films.