Patent ID: 7564536

Claim:
A lithographic apparatus, comprising: an article support constructed to support a first article, capable of imparting a radiation beam with a pattern in its cross-section to form a patterned radiation beam, in a beam path of the radiation beam or a second article to be placed in a beam path of the patterned radiation beam, the article support comprising: a plurality of supporting protrusions on which the first article or the second article is disposed in use, wherein the plurality of supporting protrusions are constructed to define a support zone to provide a plane of support for the first article or the second article, so that when the first article or the second article is subjected to a thermal load the support zone allows at least a portion of the first article or the second article to expand or contract to reduce the build up of a mechanical stress in the first article or second article, respectively, while maintaining the first article or second article substantially fixed to the article support, and a position sensor configured to determine a position offset, in a direction lying in the plane of the support zone, of the first article or the second article over a period of time; and a projection system configured to project a patterned radiation beam onto a target portion of a second article.