Patent ID: 9606448
Date: 2017-03-28
CPC Classifications: G03F,Y10S

Claim:
1. A lithographic projection apparatus, comprising; a projection system configured to project a pattern from a patterning device onto a substrate, the projection system comprising an optical element through which the pattern is projected, the optical element having a bottom surface and a side surface above the bottom surface; a liquid supply system configured to at least partly fill a space between the projection system and the substrate with a liquid; and a liquid confinement member configured to constrain liquid within the space, the liquid confinement member having a surface extending above the bottom surface of the optical element and facing the side surface of the optical element, wherein a gap between the surface of the liquid confinement member and the side surface of the optical element allows liquid to flow therein, wherein the optical element of the projection system has, on the side surface configured to be in contact with the liquid in the gap, a protective coating arranged to have liquid in contact therewith in the gap.