Patent ID: 7995185

Claim:
An aberration control system within an immersion lithography system that compensates for an aberration due to a heating effect of exposure energy in an immersion fluid across an exposure zone, comprising: one or more actuators that adjust optical elements within the immersion lithography system; a fluid heating compensation module coupled to the one or more actuators, the fluid heating compensation module being constructed and arranged to determine actuator commands to make adjustments to optical elements within the immersion lithography system based on changes in one or more of a flow rate of the immersion liquid, an exposure dose and a reticle pattern image, wherein, the fluid heating compensation module determines actuator commands by calculating the optical path length difference (OPD) from one side of the exposure zone to the other side due to the heating effect based on physical characteristics such as the fluid density, heat capacity, and optical properties, and, an interferometric sensor coupled to the fluid heating compensation module and configured to determine light intensity patterns in the exposure zone to provide pre-calibration of the fluid heating compensation module for the aberration, where the pre-calibration is also based on the exposure dose and the flow rate of the immersion liquid.