TETRAHEDRAL AMORPHOUS-CARBON FILMS PREPARED BY MAGNETRON SPUTTERING AND DC ION PLATING

Highly tetrahedral, dense amorphous carbon (ta-C) films have been depo sited using rf sputtering of graphite by an unbalanced magnetron with intense dc Ar-ion plating at low temperatures (<70 degrees C). The rat io of the argon ion flux to neutral carbon flux Phi(i)/Phi(n) is about 5. The film density and compressive stress are found to pass through a maximum of 2.7 g/cm(3) and 16 GPa, respectively, at an ion plating e nergy of about 100 eV. Experiments with higher ion flux ratios of Phi( i)/Phi(n) = 10 show that it is possible to deposit carbon films with d ensities up to 3.1 g/cm(3) and sp(3) contents up to 87%. Deposition of ta-C in this experiment when the energetic species is Ar appears to r equire a minimum stress of 14 GPa to create significant sp(3) bonding, which contrasts with the continuous increase in sp(3) content with st ress when the energetic species is C ions themselves. These results ar e used to discuss possible deposition mechanisms. (C) 1996 American In stitute of Physics.