US Patent 8233135 Lithographic apparatus and device manufacturing method

A lithographic apparatus includes a projection system configured to project a patterned radiation beam onto a substrate supported by a substrate table; a liquid supply system configured to supply a space between the projection system and the substrate with a liquid; a closing surface configured to provide a confining surface for liquid supplied by the liquid supply system in place of the substrate; and a closing surface positioning device configured to create and maintain a gap between the liquid supply system and the closing surface so that the liquid flows in the gap when the closing surface is used to confine the liquid supplied by the liquid supply system.