A microscope coherent optical processor based on the VanderLugt optical correlator is applied to the measurement of registration error in multilayer integrated-circuit wafers. A treatment of the effects of wafer faults on the correlation signal is given. Threshold criteria and fault-induced peak splitting of the correlation signal from reject production samples are exploited to demonstrate the easy and rapid detection of faults in partially processed integrated-circuit wafers.
© 1994 Optical Society of America
Xian Y. Cai, Frank Kvasnik, and Roy W. Blore, "Wafer fault measurement by coherent optical processor," Appl. Opt. 33, 4487-4496 (1994)