Abstract: A lithographic apparatus has a mask table adapted to accommodate a mask in at least two positions so that a mask with a pattern area larger than the exposure field can be imaged by first performing an exposure with the mask in the first position and then performing a second exposure with the mask in the second position.

Abstract: In a projection system a pattern plane on a reticle is illuminated to have a projection image focussed on an image plane. The presence of a pellicle in the optical path causes a virtual shift of the position of the pattern plane on the reticle. Depending on the presence or absence of the pellicle the image plane of the projection image needs to be adapted for proper focussing. A compensator counteracts the virtual shift of pattern plane due to the pellicle, by shifting the position of the pattern plane.

Abstract: In a lithographic apparatus using exposure radiation of a relatively short wavelength, e.g. 157 or 126 nm, a laminar flow of N2 is provided across parts of the beam path in or adjacent to moving components of the apparatus. A variety of structures may be used to provide the laminar flow including a screen, a settling chamber, an angled inlet port and a flow path having increasing cross-sectional area.

Abstract: In a projection system a pattern plane on a reticle is illuminated to have a projection image focussed on an image plane. The presence of a pellicle in the optical path causes a virtual shift of the position of the pattern plane on the reticle. Depending on the presence or absence of the pellicle the image plane of the projection image needs to be adapted for proper focussing. A compensator counteracts the virtual shift of pattern plane due to the pellicle, by shifting the position of the pattern plane.

Abstract: A lithographic apparatus has an inner purge compartment surrounding and moving with a moveable component such as a mask table or a substrate table and an outer purge compartment surrounding the inner purge compartment. Purge gas is supplied to the inner compartment and exhausted from the outer compartment so that the inner purge compartment is at an average pressure higher than ambient and the outer compartment is at a pressure lower than ambient. Even when acceleration of the moveable object and compartments cause local pressure variations, the inner compartment is at a higher pressure than the outer compartment so that any gas flow is outward and contamination is prevented from reaching the inner compartment.

Abstract: In a lithographic apparatus using exposure radiation of a relatively short wavelength, e.g. 157 or 126 nm, a laminar flow of N2 is provided across parts of the beam path in or adjacent to moving components of the apparatus. A variety of structures may be used to provide the laminar flow including a screen, a settling chamber, an angled inlet port and a flow path having increasing cross-sectional area.

Abstract: A lithographic apparatus has an inner purge compartment surrounding and moving with a moveable component such as a mask table or a substrate table and an outer purge compartment surrounding the inner purge compartment. Purge gas is supplied to the inner compartment and exhausted from the outer compartment so that the inner purge compartment is at an average pressure higher than ambient and the outer compartment is at a pressure lower than ambient.