Patent ID: 8233134

Claim:
A lithographic apparatus comprising: a projection system configured to project a patterned radiation beam onto a target portion of a substrate, the projection system having a final element; a barrier member surrounding a space between the projection system and, in use, the substrate, to define in part with the final element a reservoir for liquid, the barrier member being spaced from the final element to define a gap therebetween; and a deformable seal between a radially outer surface of the final element and a radially outer surface of the barrier member, the deformable seal being configured to substantially prevent a gas from flowing past the seal towards or away from the reservoir of liquid and configured to allow fluid to pass the seal when liquid is between the radially outer surface of the final element and the radially outer surface of the barrier member, wherein the deformable seal is located between a substantially horizontal surface of the barrier member and a substantially horizontal surface of the final element.