Ž . Diamond and Related Materials 10 2001 10631069 Tribological and mechanical properties of diamond-like carbon prepared by high-density plasma J.C. Sanchez-Lopez a,  , C. Donnet a , J.L. Loubet a , M. Belin a , A. Grill b , V. Patel b , ´ ´ C. Jahnes b a Ecole Centrale de Lyon, Laboratoire de Tribologie et Dynamique des Systemes, UMR 5513 Bat. H10, BP 163, Ecully cedex F-69131, ` France b IBM Research Di  ision, T. J. Watson Research Di  ision, Yorktown Heights, NY, USA Abstract Ž . Diamond-like carbon films DLC have been deposited by plasma-enhanced chemical vapor deposition using a commercial r.f. Ž . high-density plasma HDP . The hardness and elastic modulus have been determined from force  displacement curves using a nanoindentation instrument. The friction coefficients and wear rates have been measured using a pin-on-flat tribometer in ambient air and UHV at maximum Hertzian contact pressure of 1.09 GPa. It was found that the hardness, Young’s modulus, and wear resistance of the films increased with decreasing hydrogen content of the films. A viscoplastic behavior has been observed for films with hydrogen content higher than 30% indicating that these films have a softer ‘polymer-like’ structure. The unbound hydrogen present in the HDP films contributes to the enhancement of the viscoplastic behavior of the film and to the decrease of the friction in UHV. The correlation between viscoplastic properties, film structure and tribological behavior of the HDP films is presented and compared to those obtained with samples prepared by d.c. PECVD.  2001 Elsevier Science B.V. All rights reserved. Keywords: Diamond-like carbon; High-density plasma; Tribology; Nanoindentation 1. Introduction Diamond-like carbon films, designated as DLC, de- scribes a variety of amorphous carbon materials some Ž containing up to approximately 50 at.% hydrogen a- . Ž . C:H , others containing less than 1% hydrogen a-C . Depending on the hydrogen concentration and sp 3 sp 2 bonding ratios, which may be controlled by the deposi- tion process, they can exhibit a wide range of mechani-  cal and tribological behaviors 1 . Hardness values span  Corresponding author. Tel.: 33-472-186-267; fax: 33-478-433- 383. Ž . E-mail address: jsanchez@ec.lyon.fr J.C. Sanchez-Lopez . ´ ´ from 3 GPa for soft films prepared by plasma decom- position of hydrocarbon gases to approximately 40  80 GPa for the hardest films deposited by mass- and 12    energy-separated C ions 2,3 . In the field of tri- bology, the friction and wear strongly depend both on the environmental conditions and the nature of the  coatings, as determined by the deposition process 4. In high-density plasmas, a high degree of ionization is obtained at low pressures and therefore, less thermal- ization of ions occurs in the plasma sheath. The DLC films thus grow under intense bombardment of high ion fluxes, whose energies are close to the substrate bias. These deposition conditions have demonstrated to pro- duce DLC films with lower hydrogen content and lower fraction bounded to carbon than conventional capaci- 0925-963501$ - see front matter  2001 Elsevier Science B.V. All rights reserved. Ž . PII: S 0 9 2 5 - 9 6 3 5 00 00428-3