Properties and durability of thin a-C:H overcoats produced by plasma enhanced chemical vapor deposition

Radio-frequency plasma enhanced chemical vapor deposition (RF-PECVD) technique was used to deposit thin amorphous hydrogenated carbon (a-C:H) overcoats on glass ceramic disc substrates. Raman spectroscopy results showed that higher sp(3) carbon content films can be obtained by applying appropriate kinetic energy of ion bombardment (similar to 100 eV) during film growth. However, a higher content of hydrogen was also observed in such films. The results suggest that a certain fraction of sp(3) carbon bonds is likely to be terminated by hydrogen and become dangling bonds. These dangling bonds may be important to the durability performance in the tribe-contact interface. The highly hydrogenated carbon overcoats (similar to 40 at.%) showed significant improvement in tribological performance compared with the less hydrogenated films. The contact-start-stop test at ambient environment of such overcoats showed good durability over 10 K cycles at the him thickness of 3.6 nm. (C) 2000 Elsevier Science B.V. All rights reserved.