KLA Corporation
System and method for wafer-by-wafer overlay feedforward and lot-to-lot feedback control

Abstract:

An overlay control system is disclosed. In embodiments, the system may include a controller configured to: acquire a set of feedback overlay measurements based on a plan of record (POR) sampling map on a second layer of samples of at least one previous lot of samples; generate a reference wafer overlay map based on the set of feedback overlay measurements; acquire a set of feedforward overlay measurements based on a feedforward sampling map on a first layer of a set of samples of a current lot of samples; generate a set of artificial overlay vector maps for the set of samples of the current lot of samples based on the set of feedforward overlay measurements; and cause a lithography tool to fabricate a second layer of samples of the current lot of samples based on the reference wafer overlay map and the set of artificial overlay vector maps.