Abstract: A system and method for uniformity correction is provided. The system includes a plurality of winged correction elements inserted into the illumination field in a defined configuration. Adjacent winged correction elements are overlapped to minimize induced uniformity ripple. Each winged correction element has a first protrusion on a longitudinal edge of the correction element and a second protrusion on the opposite longitudinal edge. The slope of a sloped edge of the first protrusion and the slope of a sloped edge of the second protrusion are tied to the slope of a gradient in the non-uniformity profile of the illumination field. In addition, the angles defined by the flat tip of the correction element and the sloped edge of the first and second protrusions are tied to the angle of a gradient of the illumination field.

Abstract: In a lithographic projection system, the radiation energy delivered to the substrate needs to be accurately controlled. Attenuation by injecting an absorbent gas into a volume through which the radiation passes is a convenient way to control the energy. Additionally, the interaction between gasses and the radiation may be used to measure the energy of the radiation with minimal disruption to the radiation.