Patent ID: 8068212

Claim:
A lithographic apparatus comprising: an illumination system configured to condition a radiation beam so as to illuminate a patterning device; a support constructed to support the patterning device, the patterning device being capable of imparting the radiation beam with a pattern in its cross-section to form a patterned radiation beam; a substrate table constructed to hold a substrate; a projection system configured to project the patterned radiation beam onto a target portion of the substrate, the projection system having at least one optical element that is sensitive to heat; and a control system configured to control the illumination system, the support and the substrate table to project images of the pattern onto a substrate using a corrected dose that differs from a nominal dose by an amount determined to compensate for variations in a critical dimension of projected features due to heating of the optical element, wherein the control system is configured and arranged to apply dose corrections to the image by controlling at least one of the group consisting of: an output of a radiation source, a variable attenuator, an exposure duration, a device configured to vary intensity of a radiation beam across a length of an illumination slit, a width of an illumination slit, a scan speed, movement, within a field of the image, of a neutral density filter having a non-uniform absorption pattern, and a dynamically-adjustable slit.