High precision hybrid bonding alignment system with visible laser

초록

Recently, Monolithic 3d integration and Through Silicon Via(TSV) have been used to increase the integration density of the devices for continuing Moore’s law. They would have limitations such as process temperature and less number of input/output (IO), respectively. To solve this problem, Direct Bond Interconnect (DBI) technology, which uses hybrid bonding to form the dielectric-to-dielectric bond and Cu-to-Cu bond at low temperature, has large number of IOs and good electrical performance without thermal degradation. However, the conventional wafer alignment system using IR laser could not perform a precise alignment less than 1 μm resolution. In this study, we suggest a next-generation hybrid bonding system for aligning up to submicron resolution with the visible laser radiated between wafers. The alignment key mark for DBI is patterned during last Cu pad process in the BEOL process without any additional process. In addition, unlike the IR laser used only for Si wafers, it can be used for other wafers as well. the new alignment technique can check the translational, rotational misalignment and, wafer tilt at the same time. Light simulation that it is possible to align down to 100nm resolution with this technique