Highly tetrahedral, dense amorphous carbon (ta‐C) films have been deposited using rf sputtering of graphite by an unbalanced magnetron with intense dc Ar‐ion plating at low temperatures (<70 °C). The ratio of the argon ion flux to neutral carbon flux &Fgr;i/&Fgr;nis about 5. The film density and compressive stress are found to pass through a maximum of 2.7 g/cm3and 16 GPa, respectively, at an ion plating energy of about 100 eV. Experiments with higher ion flux ratios of &Fgr;i/&Fgr;n=10 show that it is possible to deposit carbon films with densities up to 3.1 g/cm3andsp3contents up to 87%. Deposition of ta‐C in this experiment when the energetic species is Ar appears to require a minimum stress of 14 GPa to create significantsp3bonding, which contrasts with the continuous increase insp3content with stress when the energetic species is C ions themselves. These results are used to discuss possible deposition mechanisms. ©1996 American Institute of Physics.