FILTERED SADDLE FIELD FAST ATOM BEAM DEPOSITION OF DIAMOND-LIKE CARBON-FILMS

An innovation to separate out ionic and neutral radicals from the beam coming out of a saddle field fast atom beam (FAB) source is reported. Diamondlike carbon (DLC) films were grown simultaneously by these ion ic and filtered neutral radicals using methane (CH4) as the source gas in the FAB source, on to the substrates placed at different positions inside the deposition chamber. Faraday cup measurements carried out o n the two beams confirm the separation of ionic and neutral radicals. It was found that the DLC films deposited by neutral radicals have hig her hardness values (980-1070 kg/mm(2)) than those deposited by ionic radicals (810-970 kg/mm(2)), whereas, the values of optical band gap a nd refractive index are found to be higher in DLC films deposited by i onic radicals than those deposited by neutral radicals. It is emphasiz ed that during normal operation of a saddle field source, to grow DLC films, one essentially has a mixed deposition with contributions both from neutral and ionized radicals. Higher hardness values (1050-1150 k g/mm(2)) of films grown this way may, perhaps, be due to an ion assist ed process of network compaction leading to higher degree of overstrai ning. (C) 1998 American Vacuum Society.