This paper describes low temperature Au-Au bonding with vacuum ultraviolet (VUV) irradiation in the presence of oxygen gas. The VUV/O 3 treatment can remove organic contaminants of Au surfaces without damages. The Au surfaces after the VUV/O 3 treatment were analyzed by X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). The results show that carbon-based contaminants were dramatically decreased and that there were no serious damages in Au surfaces by the VUV/O 3 treatment. The Au-Au bonding with VUV/O 3 treatment was achieved at 200 °C. The average of shear strength of about 80 MPa per unit area was obtained. Therefore, it was proved that VUV/O 3 treatment is effective in Au-Au bonding.