Patent ID: 8634053

Claim:
A lithographic projection apparatus having a projection system to project a pattern from a patterning device onto a substrate, the apparatus comprising a liquid confinement structure to at least partly confine a liquid to a space between the projection system and the substrate, the liquid confinement structure comprising: a plurality of outlets in a bottom surface of the liquid confinement structure, the plurality of outlets configured to remove liquid from the space and gas from outside the space to substantially pin a meniscus of the liquid in the space due to the creation of a gas flow, the outlets being distributed around the space such that the meniscus extends around the space, each outlet having a cross-sectional dimension of 0.2 mm or greater, and being, in plan, spaced apart from each other between 0.25 and 10 times their maximum plan dimension and two or more outlets of the plurality of the outlets not being at the bottom of a groove in the bottom surface.