Patent ID: 8810915

Claim:
A lithographic projection apparatus comprising: a projection system having a last element from which an exposure light is projected through liquid in a space under the last element, a light incident surface of the last element having a convex shape; a liquid retaining member disposed adjacent to a surface of the last element through which the exposure light does not pass, the liquid retaining member having an undersurface under which liquid is retained; and a gap formed between the liquid retaining member and the surface of the last element, the gap being in fluidic communication with the space, the gap including a lower portion and an upper portion between which the gap extends, wherein a wafer moves below and relative to the last element and the liquid retaining member; the liquid is retained between the last element and the undersurface of the liquid retaining member on one side and an upper surface of the wafer on the other side; and the liquid locally covers a portion of the upper surface of the wafer to expose the wafer by projecting the exposure light onto the wafer through the liquid in the space.