Vacuum ultraviolet irradiation treatment for reducing goldgold bonding temperature

Lowerature AuAu bonding was achieved under vacuum ultraviolet irradiation in the presence of oxygen gas (VUV/O3). The Au surfaces obtained after the VUV/O3 treatment were analyzed by X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) measurements. The results indicate that the amount of carbon-based contaminants was dramatically decreased and that there was no serious damage to Au surfaces caused by the VUV/O3 treatment. The AuAu bonding temperature was successfully reduced to 150°C after the VUV/ O3 treatment. The average shear strength was approximately 56 MPa, and cross-sectional scanning electron microscopy (SEM) images of the bonded samples confirmed the absence of voids and cracks. Therefore, VUV/O3 treatment is highly effective for achieving lowerature AuAu bonding.