Following the thermocompression bonding of the CIS and ISP wafers A2 and the subsequent bulk backside surface grinding, the top CIS wafer is drastically thinned while the bottom ISP wafer remains thick (Engineering Practice).Because surface grinding removes bulk material uniformly across the top surface without altering the wafer's circular perimeter, it inherently leaves a razor-sharp, fragile "knife-edge" at the periphery of the thinned wafer A2.Furthermore, the extreme periphery of bonded waf