Patent ID: 8208120

Claim:
A lithographic apparatus comprising a substrate table to hold a substrate; a projection system to project a patterned beam of radiation onto a target portion of the substrate; and a liquid supply system configured to at least partly fill a space between the projection system and the substrate table, with a liquid through which the beam is to be projected, the liquid supply system comprising a liquid confinement structure extending along at least a part of the boundary of the space between the projection system and the substrate table, the liquid confinement structure comprising: an aperture through which the patterned beam of radiation is projected onto the target portion of the substrate, a gas knife configured to supply gas at a high pressure in a small area to between the liquid confinement structure and the substrate table, an inlet to supply liquid, the inlet formed in a face of the liquid confinement structure that opposes the substrate table, an outlet configured to remove at least liquid between the liquid confinement structure and the substrate table, and a recess radially outward, relative to the optical axis of the projection system, of the aperture, the recess, in use, at ambient pressure, wherein a porous member is disposed over the outlet to evenly distribute liquid flow over the area of the outlet, wherein the gas knife is configured to supply gas outward, relative to the space, of the porous member, and wherein the inlet is located inward, relative to the space, of the porous member, located between the substrate table and a surface of the projection system in contact with the liquid, and at least in part angled from vertical to provide a liquid flow with a direction away from the porous member.