Measurement modes for overlay

An overlay metrology tool comprising:

• an illumination source;
• one or more illumination optics configured to illuminate an overlay target on a sample with one or more illumination beams from the illumination source, wherein the overlay target includes periodic features along one or more measurement directions;
• one or more collection optics configured to direct diffracted light from the overlay target to a detector;
• an adjustable pupil mask located at a pupil plane, wherein the pupil plane corresponds to a collection pupil plane, wherein the adjustable pupil mask includes one or more control zones distributed across one or more portions of the pupil plane, wherein the one or more control zones are individually addressable to provide an adjustable pupil transmissivity distribution, wherein the adjustable pupil transmissivity distribution provides selective control of the passage of diffracted light in the respective one or more portions of the pupil plane to the detector, wherein the one or more control zones provide operability of the overlay metrology tool according to two or more measurement modes utilizing different pupil transmissivity distributions;
• and
• a controller communicatively coupled to the adjustable pupil mask, the controller including one or more processors configured to execute program instructions causing the one or more processors to:
• receive overlay metrology recipes for a plurality of overlay targets on the sample associated with selected measurement modes of the two or more measurement modes;
• direct the adjustable pupil mask to adjust the pupil transmissivity distribution according to the respective overlay metrology recipes associated with the selected measurement modes of the two or more measurement modes for measurements of the plurality of overlay targets on the sample;
• and
• determine overlay measurements along the one or more measurement directions associated with the selected measurement modes of the two or more metrology modes for the plurality of overlay targets on the sample based on measurement data from the detector.

A method comprising:

• receiving overlay metrology recipes for one or more overlay targets on a sample;
• directing an adjustable pupil mask to adjust a pupil transmissivity distribution according to the respective overlay metrology recipes for measurements of the one or more overlay targets on the sample with an overlay metrology tool, wherein the overlay metrology tool comprises:
• one or more illumination optics configured to illuminate an overlay target with one or more illumination beams from an illumination source, wherein the overlay target includes periodic features along one or more measurement directions;
• one or more collection optics configured to direct diffracted light from the overlay target to a detector;
• and
• the adjustable pupil mask located at a pupil plane, wherein the pupil plane corresponds to a collection pupil plane, wherein the adjustable pupil mask includes one or more control zones distributed across one or more portions of the pupil plane, wherein the one or more control zones are individually addressable to provide an adjustable pupil transmissivity distribution, wherein the adjustable pupil transmissivity distribution provides selective control of the passage of diffracted light in the respective one or more portions of the pupil plane to the detector, wherein the one or more control zones provide operability of the overlay metrology tool according to two or more measurement modes utilizing different pupil transmissivity distributions;
• and
• determining overlay measurements along the one or more measurement directions associated with the one of the one or more metrology modes for the one or more overlay targets on the sample based on measurement data from the detector.