Abstract: In an immersion lithography apparatus, a member surrounds a space between a projection system and a substrate table. A seal is formed to contain liquid in the space.

Abstract: A map of the surface of a substrate is generated at a measurement station. The substrate is then moved to where a space between a projection lens and the substrate is filled with a liquid. The substrate is then aligned using, for example, a transmission image sensor and, using the previous mapping, the substrate can be accurately exposed. Thus the mapping does not take place in a liquid environment.

Abstract: In an off-axis levelling procedure a height map of the substrate is generated at a measurement station. The height map is referenced to a physical reference surface of the substrate table. The physical reference surface may be a surface in which is inset a transmission image sensor. At the exposure station the height of the physical reference surface is measured and related to the focal plane of the projection lens. The height map can then be used to determine the optimum height and/or tilt of substrate table to position the exposure area on the substrate in best focus during exposure. The same principles can be applied to (reflective) masks.