Wafer bonding technology has been evolving as an important semiconductor manufacturing process step, along with the performance and device scaling of integrated circuits. Bonding technology has applications for wafer substrates in SOI manufacturing, device processes in MEMS, CMOS imager products, and plays a crucial role in back-end and packaging processes for heterogeneous integration era. As I/O channels get denser, control of the bonding process needs to follow. Critical dimension (CD) and overlay metrology, derived from process requirements, need to operate in the one-digit nanometer range, and inspection systems in the sub-micrometer range.
