Patent ID: 7375353
Filing Date: 2008-05-20
Classification: G03F

Abstract:
1. A lithographic apparatus comprising: an illumination system configured to condition a radiation beam; a support constructed to support a patterning device, the patterning device being constructed to impart a cross-sectional pattern to the radiation beam to form a patterned radiation beam; a substrate table constructed to hold a substrate; a projection system configured to project the patterned radiation beam onto a target portion of the substrate; an attenuation adjustment device comprising a plurality of members configured to cast penumbras in the radiation beam illuminating the patterning device; and an attenuation control device to adjust the members so as to control attenuation of the patterned radiation beam across the cross-section of the patterned radiation beam, the attenuation control device incorporating a position detector configured to provide an output indicative of the position of each member in dependence on detection of a beam of detecting radiation reaching the position detector after attenuation, wherein the attenuation control device incorporates a common radiation source configured to generate beams of detecting radiation to detect positions of the members.