DIAMOND-LIKE CARBON-FILMS PREPARED BY VARIOUS ION-BEAM-ASSISTED TECHNIQUES

Diamond-like carbon (DLC) films were deposited by dual ion beam sputtering (DIBS) and ion-beam-assisted d.c. magnetron (IBAM) sputtering. The magnetron or a Kaufman ion gun using 1 keV argon ions caused the sputtering of the graphite target; a second ion source assisted the growth process by bombarding the film with 50-200 eV argon ions. Homogeneous, adherent films were obtained on glass, steel and silicon substrates, with a maximum deposition rate of 0.08 nm s-1 at a pressure of 6 x 10(-2) Pa (IBAM sputtering). The layers were characterized by their hardness which reached 40 000 MPa, their very dense morphology and a strong optical absorption in the visible region. No interface was detected at the substrate surface by IR spectroscopy. Other methods, such as Raman spectroscopy, Rutherford backscattering spectrometry, elastic recoil detection analysis and ellipsometry, provided important information which was used to determine the effect of ion bombardment parameters (ion energy, nature and flow) and working pressure. The Raman signature was representative of amorphous carbon. The density varied in the range 1.8-2.7 g cm-3 for DIBS films when the ion beam specifications were altered, and the argon concentration increased from 1 to 2.5 at.% when the film growth was assisted. The hydrogen content remained low (0.5-1 at.%). Furthermore, the ion beam bombardment increased the optical indices. Finally, the film preparation conditions were optimized to reduce film contamination and residual stress.