The CIS/ISP wafer bond pairing relies on Direct Bond Interconnect (DBI) technology, which requires perfectly planar and highly reactive surfaces to achieve robust Cu-to-Cu and dielectric-to-dielectric hybrid bonds at low temperatures P2.Following the post-CMP cleaning, the planarized CIS wafer surface must be physically and chemically prepared to initiate spontaneous adhesion with the ISP wafer upon contact P4.The RF surface activation step serves exactly this purpose by transforming the passive