US Patent 7088431 Lithographic apparatus and device manufacturing method

A lithographic apparatus includes an illumination system for providing a beam of radiation, an article support for supporting a flat article to be placed in a beam path of the beam of radiation on the article support, an electrostatic clamp for clamping the article against the article support by an electrostatic field during projection, and a recessed backfill gas feed arranged in the article support for feeding backfill gas to a backside of the article when supported by the article support. According to one aspect of the invention, the recessed backfill gas feed includes a shielding layer for shielding the backfill gas in the recessed backfill gas feed from the electrostatic field.