Manufacturing superconducting circuits out of ultrathin films is a challenging task when it comes to patterning complex compounds, which are likely to be deteriorated by the patterning process. With the purpose of developing high- T c superconducting photon detectors, we designed a novel route to pattern ultrathin YBCO films down to the nanometric scale. We believe that our method, based on a specific use of a focused-ion beam, consists of locally implanting Ga 3 + ions and/or defects instead of etching the film. This protocol could be of interest for engineering high- T c superconducting devices (SQUIDS, SIS/SIN junctions and Josephson junctions), as well as to treat other sensitive compounds.