Patent ID: 11880142
Assignee: KLA CORPORATION
Field: Optics (Instruments)
Classification: CPC G | IPC G

Claim 33:
34. A method for self-calibrating overlay metrology comprising:
generating device overlay data for a plurality of device targets on a sample with one or more overlay metrology tools;
determining preliminary device overlay measurements for the plurality of device targets including device-scale features using an overlay recipe with the device overlay data as inputs;
generating assist overlay data for one or more assist targets on the sample including the device-scale features using the at least one overlay metrology tool, wherein at least one of the one or more assist targets has a programmed overlay offset of a selected value along a particular measurement direction;
determining self-calibrating assist overlay measurements for the set of assist targets based on the assist overlay data; and
generating corrected overlay measurements associated with each of the one or more overlay metrology tools for the plurality of device targets by adjusting the preliminary device overlay measurements based on the self-calibrating assist overlay measurements.