Lithographic apparatus and device manufacturing method using overlay measurement

A device manufacturing method for transferring a pattern from a patterning device onto a substrate and for performing an overlay measurement, comprising:

• providing a reference set of gratings in the substrate, the, reference set comprising two reference gratings having line elements in a first direction, and only one reference grating having line elements in a second direction, the second direction being substantially perpendicular to the first direction;
• providing a measurement set of gratings on top of the reference set of gratings, the measurement set comprising measurement gratings similar to the reference gratings, in which two of the measurement gratings are oppositely biased in the second direction relative to the respective two reference gratings and one of the measurement gratings is not biased in the first direction relative to the respective only one reference grating;
• measuring asymmetry of only the reference gratings having line elements in the first direction and the only one reference grating having line elements in the second direction;
• and
• deriving from the measured asymmetry the overlay in both the first and second direction.

A lithographic apparatus arranged to transfer a pattern from a patterning device onto a substrate, comprising:

• a first grating pair comprising:
• a measurement grating and a reference grating on top of each other, each grating comprising:
• line elements disposed in a first direction,
• wherein the measurement grating line elements are biased in a second direction relative to the reference grating line elements;
• a second grating pair comprising:
• a measurement grating and a reference grating on top of each other, each grating comprising:
• line elements disposed in a first direction,
• wherein the measurement grating line elements are biased in a second direction relative to the reference grating line elements and opposite the bias direction of the measurement grating line elements of the first grating pair;
• only one grating pair comprising:
• a measurement grating and a reference grating on top of each other, each grating comprising:
• line elements disposed in a second direction;
• and
• an overlay measurement device, the overlay measurement device being configured to measure asymmetry of only the first, second, and only one grating pairs, and to derive from the measured asymmetry the overlay in both the first and second direction.