Methods and patterning devices and apparatuses for measuring focus performance of a lithographic apparatus, device manufacturing method

A patterning device for use in a lithographic apparatus, the patterning device comprising:

• portions that define one or more device patterns;
• and
• portions that define one or more metrology patterns,
• wherein the metrology patterns include at least one focus metrology pattern, the focus metrology pattern comprising at least a first array of features in which the features at any location of a plurality of locations within the first array define a pattern that repeats in at least a first direction of periodicity, and at least one geometric parameter of the repeating pattern varies from location to location over the first array, whereby measurement of focus performance using repeating patterns having different geometric parameters can be performed by measuring a property of the printed focus metrology pattern using a selected subset of the locations across the first array.

A metrology apparatus for measuring focus performance of a lithographic process, the metrology apparatus being operable to:

• receive a substrate having a focus metrology pattern printed thereon, the focus metrology pattern including an array of features, wherein features in the array of features at any location of a plurality of locations define a repeating pattern that repeats in at least a first direction of periodicity, and wherein at least one geometric parameter of the repeating pattern varies from location to location over the array of features;
• measure a property of the focus metrology pattern at least at a selected subset of the plurality of locations across the array of features;
• and
• derive a measurement of focus performance from the property as measured at the selected subset of the locations measured across the array of features, whereby the repeating pattern upon which the measurement of focus performance is based has geometric parameters determined partly by selection of the subset of locations within the array of features.

A system comprising:

• a substrate having a focus metrology pattern printed thereon, the focus metrology pattern including an array of features, wherein features in the array of features at any location of a plurality of locations define a repeating pattern that repeats in at least a first direction of periodicity, and wherein at least one geometric parameter of the repeating pattern varies from location to location over the array of features;
• and
• a non-transitory computer program product comprising processor readable instructions which, when run on suitable processor controlled apparatus, cause the processor controlled apparatus to:
• measure a property of the focus metrology pattern at least at a selected subset of the plurality of locations across the array of features;
• and
• derive a measurement of focus performance from the property as measured at the selected subset of the locations measured across the array of features, whereby the repeating pattern upon which the measurement of focus performance is based has geometric parameters determined partly by selection of the subset of locations within the array of features.