Structure and properties of ta-C films deposited by filtered cathodic vacuum arc technology as a function of substrate bias

Tetrahedral amorphous carbon (ta-C) films have been deposited on P-type (100) polished c-silicon wafer with different substrate negative bias by filtered cathodic vacuum arc technology. The microstructure of ta-C films was measured by visible Raman spectroscopy and the spectra was fitted with a single skewed Lorentzian peak described by BWF function. The coupling coefficient characterizes the asymmetric degree of the spectra and is correlated with the sp³ content. The surface morphology and mechanical properties were researched respectively by AFM and Nano-Indentor. When the substrate bias is -80 V, the sp³ content is the most, the root mean square surface roughness is the least (R_q=0.23 nm) and hardness (51.49 GPa), Young's modulus (512.39 GPa), and critical scratching load (11.72 mN) are the highest. As the substrate bias increases or decreases, the sp³ content and other properties decrease correspondingly.