SUBSTRATE FOR USE IN METROLOGY, METROLOGY METHOD AND DEVICE MANUFACTURING METHOD.

摘要

A pattern from a patterning device is applied to a substrate. The applied pattern includes device functional areas and metrology target areas. Each metrology target area comprises a plurality of individual grating portions, which are used for diffraction based overlay measurements or other diffraction based measurements. The gratings are of the small target type, which is small than an illumination spot used in the metrology. Each grating has an aspect ratio substantially greater than 1, meaning that a length in a direction perpendicular to the grating lines which is substantially greater than a width of the grating. Total target area can be reduced without loss of performance in the diffraction based metrology. A composite target can comprise a plurality of individual grating portions of different overlay biases. Using integer aspect ratios such as 2:1 or 4:1, grating portions of different directions can be packed efficiently into rectangular composite target areas.