GROWTH MECHANISMS OF DLC FILMS FROM C+ IONS - EXPERIMENTAL STUDIES

Experimental studies aiming at the elucidation of the as yet poorly understood growth mechanisms of DLC films from C+ ions are described. Three main characterization methods are employed: (i) atomic force microscopy (AFM) for nanometer characterization of the surface morphology; (ii) Rutherford backscattering spectroscopy (RBS) combined with profilometry for density measurements; and (iii) electron energy loss spectroscopy (EELS) for analysis of the bonding configuration (sp(3)/sp(2)). DLC films were deposited on Si substrates using mass selected C+ ions with well-defined energies in the range 5 eV-2 keV at different substrate temperatures in the range 25-250 degrees C. The data indicate that sp(3) film deposition is associated with internal subsurface growth of very smooth films while sp(2) rich film formation is associated with surface growth processes of much rougher films. The data is in accord with and substantiates the subplantation model that treats low energy ion beam deposition in terms of a shallow implantation process.