Sonoscan’s AW2000 systemfor automated inspection of bonded wafer can handle objects up to 200mm in diameter, which is especially useful in imaging after initial Van-der-Waals bonding. After this process, the wafers are joined only by weak chemical forces, and can be easily separated. Separated wafers are cleaned and then rebonded. Inspection at this point avoids further processing of defective wafer pairs. Automated acoustic imaging also serves as a process monitor for the initial bonding step. The system classifies inspected wafers, and is capable of imaging defects having sizes as small as 5 to 10µm. If needed, acoustic imaging can also be performed after annealing and thinning.
