We have studied the T-c degradation of epitaxial YB2Cu3O7-x (YBCO) films on (100) LaAlO3 substrates implanted with 100 keV O+ ions at different conditions. The influence of Au mask thickness and the implantation doses on the film characteristics have been investigated systematically. YBCO bridges have been modified by local oxygen ion implantation at optimal condition through a narrow trench in an Au/photoresist mask, which was fabricated formed by focused ion beam milling and reactive ion etching. The critical current and normal resistance of the modified bridges were found to be characteristic of superconductor/normal/superconductor Josephson junction behavior. Microwave irradiation of the junctions resulted in Shapiro steps in the I-V characteristics.