Insights on the deposition mechanism of sputtered amorphous carbon films Original Research Article

Low energy Ar+ ion bombardment (LEIB) during growth of amorphous carbon (a-C) films deposited with magnetron sputtering (MS), results to dense films, rich in sp3 C–C bonds, and exhibit high hardness and compressive stress. We present here a preliminary study of the growth mechanism of a-C films deposited with negative bias voltage (LEIB) in terms of their composition, density and mechanical properties. The experimental results showed that stress and hardness are directly related with the sp3 C–C bonding in the film and described well with the so far proposed models on the formation mechanism of tetrahedral carbon. However, the film density, that is a composite property, was found to depend not only on the sp2 and sp3 content but also on a new, denser than graphite, carbon phase when the Ar+ ion energy is above ∼130 eV.