Superconducting Y‐Ba‐Cu‐O (YBCO) films have been prepared byexsituO2annealing of multilayer films deposited on yttria‐stabilized zirconia substrates by sequential rf diode sputtering of Y2O3, BaF2, and CuO targets, all of which are chemically stable. If sputtering is performed in an Ar ambient, the as‐deposited films contain sufficient F to require its removal by annealing in wet O2at about 800 °C or above before the superconducting YBCO phase can be formed by annealing in dry O2. However, sputtering in an Ar‐O2ambient greatly reduces the F content, making it possible to obtain the superconducting phase by annealing in dry O2only. If the ambient contains about 20% O2, films withTc(R=0)>85 K can be prepared without wet‐O2annealing. The Ar‐O2process therefore has the potential forinsitupreparation of superconducting YBCO films.