FORMATION OF AMORPHOUS-CARBON THIN-FILMS BY PLASMA SOURCE ION-IMPLANTATION

Amorphous carbon films were deposited by methane plasma source ion imp lantation on silicon wafer and 440C stainless steel substrates. Radio frequency power was used to produce a glow discharge plasma. Ions prod uced in the plasma are accelerated by high negative voltage pulses (ty pically -20 kV, 100 Hz, 50 mu s) applied directly to a substrate holde r stage. Structure information was obtained on the films by Raman spec troscopy. The composition analysis of the surface layer of the implant ed substrates was carried out using Auger electron spectroscopy (AES). The friction coefficients of the films were measured with the aid of a reciprocating sliding tester. The adhesive strength of the films was estimated by a scratch tester. The results showed that the structure of the films varies with the applied voltage. The carbon films produce d at high applied voltage exhibited high hardness and very low frictio n coefficient of about 0.006. The Raman spectra were divided into the ''D'' disordered peak and ''G'' graphite peak. The integrated intensit y ratio of ''D'' peak and ''G'' peak, I-D/I-G, increased at a high vol tage. The results of AES revealed that the implanted carbon penetrated the substrate resulting in a complete interfacial mixing. The adhesiv e strength of the films increased, attributed to the interfacial mixin g at the interface. (C) 1998 Elsevier Science S.A.