Wafer flatness requirements for 45nm node (65nm hp) lithography process

In order to maximize the number of applications where reclaim wafers can be used for process monitoring in the manufacturing plant including 45 nm technology node lithography process, an experiment was conducted to correlate the wafer flatness parameter (SFQR) and lithography defocusing defects. The experiment demonstrated that SFQR is an effective parameter for screening the reclaim wafers to avoid the wafer flatness driven defocusing defect generation and its value of <100 nm was appeared to be required for this 45 nm node (65 nm hp) technology processing.