Patent ID: 7671968

Claim:
A lithographic apparatus comprising: (a) an illumination system configured to condition a radiation beam; (b) a substrate table constructed to hold a substrate; (c) a stage apparatus comprising: (i) a first object table configured to hold a first patterning device; (ii) a second object table configured to hold a second patterning device, each of the first and second patterning devices including a pattern to pattern the radiation beam, and the first and second patterning devices being arranged such that the pattern of the first patterning device and the pattern of the second patterning device are adjacent to each other in a scanning direction; and (iii) a positioning device configured to position the first and second patterning devices and the substrate; (d) a projection system configured to project the patterned radiation beam onto a target portion of the substrate such that during a scanning operation the pattern of the first patterning device and the pattern of the second patterning device are projected on the substrate, and (e) a masking device, the masking device comprising (i) a first masking part configured to obscure a first part of the first patterning device before the pattern of the first patterning device is impinged by the radiation beam; (ii) a second masking part that is deformable so as to adjust a length thereof, the second masking part configured to obscure a second part of the first patterning device after the pattern of the first patterning device is impinged by the radiation beam and to obscure a first part of the second patterning device before the pattern of the second patterning device is impinged by the radiation beam, and (iii) a third masking part configured to obscure a second part of the second patterning device after the pattern of the second patterning device is impinged by the radiation beam.