Patent ID: 8692973

Claim:
A lithographic projection apparatus arranged to project a pattern onto a substrate, the apparatus comprising: a projection system via which the pattern is projected through an opening provided below the projection system; a liquid supply system which has a liquid supply port provided above the opening; and a fluid removal system including a first chamber configured to hold gas, a first open end adjacent a volume in which fluid will be present, and a second open end adjacent the volume, liquid supplied from the liquid supply port flowing into the volume through the opening, wherein: the fluid removal system removes, through a pressure differential across the first open end when gas is present in the first chamber, substantially only gas from the volume via the first open end when gas in the volume is adjacent the first open end but not liquid from the volume when liquid in the volume is adjacent the first open end; the fluid removal system removes liquid from the volume via the second open end; and a height of the first open end is different from a height of the second open end.