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

Claim 0:
1. A self-calibrating overlay metrology system comprising:
a controller including one or more processors configured to execute program instructions causing the one or more processors to:
receive device overlay data for a plurality of device targets on a sample from an overlay metrology tool;
determine 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;
receive assist overlay data for one or more assist targets on the sample including device-scale features from the 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;
determine self-calibrating assist overlay measurements for the one or more assist targets based on the assist overlay data, wherein the self-calibrating assist overlay measurements are linearly proportional to overlay on the sample; and
generate corrected overlay measurements for the plurality of device targets by adjusting the preliminary device overlay measurements based on the self-calibrating assist overlay measurements.