milling with xenon ions directed at grazing angles onto the surfaces of c-axis oriented yba/sub 2/cu/sub 3/o/sub 7/ films is shown to give smooth films which superconduct at thicknesses approaching a lattice constant. the observed linear dependence of the room temperature sheet conductance with milling time allows a determination of the effective electrical thickness after each milling stage. the resistance transitions of all films having a superconducting transition show a metallic behavior with a positive temperature coefficient of resistance. degradation of superconducting properties becomes significant for films less than 100 aa thick although this degradation is appreciably less for films which initially (before milling) have sharp resistance transitions and a strong c-axis orientation. reproducible and controlled fabrication of ultrathin films using this milling technique shows promise as an important step in the post-deposition processing of high-t/sub c/ thin films for electronic device applications