Superconducting YBCO thin films have been fabricated by sequential electron beam evaporation of metallic constituents for yttrium and copper while barium is replaced with BaF2, The conversion of BaF2 --> BaO has been attained th rough wet oxygen annealing. Correlations of stoichiometry with microstructural, as well as superconducting, properties of the films have been examined. Results are given for YBa2Cu3O7-delta thin films on SrTiO3 (100) and YSZ (100) single crystal substrates. The usefulness of the BaF2 preparation route for the fabrication of mixed phase (Y123 + Y124) and pure Y124 is also demonstrated. Microstructural properties of Y123 thin films indicate different growth processes for the two substrates.