Optimization of GCIB irradiation conditions for surface activated bonding

Gas cluster ion beam (GCIB) was used for surface activation bonding (SAB). Since GCIB modifies only near surface, low-damage surface modification and activation are expected. In this study, Cu-Cu bonding with GCIB irradiation was selected as a preliminary study. XPS and contact angle measurement showed that surface oxide on Cu was removed efficiently by oblique incidence Ar-GCIB at 5-20 kV. Also, sequential irradiation of GCIB at normal and oblique incidence realized smooth Cu surface. After that Cu-Cu bonding strength was investigated by the tensile test.