Insights on the deposition mechanism of sputtered amorphous carbon films

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 sp(3) C-C bonds, and exhibit high hardness and compressive stress. We present here a preliminary study of the growth mechanism of a-C films de posited with negative bias voltage (LEIB) in terms of their composition, de nsity and mechanical properties. The experimental results showed that stres s and hardness are directly related with the sp(3) C-C bonding in the film and described well with the so far proposed models on the formation mechani sm of tetrahedral carbon. However, the film density, that is a composite pr operty, was found to depend not only on the sp(2) and sp(3) content but als o on a new, denser than graphite, carbon phase when the Ar+ ion energy is a bove similar to 130 eV. (C) 1999 Elsevier Science Ltd. All rights reserved.