Lithographic apparatus and device manufacturing method

A device manufacturing method comprising:

• patterning a projection beam with a pattern in its cross-section, the projection beam having a position dependent intensity distribution in a pupil plane of a radiation system providing the projection beam, the position dependent intensity distribution determining an angle dependent intensity distribution of the projection beam at a substrate;
• projecting the patterned projection beam onto a target portion of a layer of radiation-sensitive material on the substrate;
• splitting an auxiliary beam from the projection beam;
• measuring an intensity distribution across the auxiliary beam;
• and
• controlling an intensity distribution at the pupil plane by returning the intensity distribution measured across the auxiliary beam via a feedback loop.

A lithographic apparatus comprising:

• a radiation system to provide a projection beam of radiation, the radiation system comprising an illumination system for defining a position dependent intensity distribution of the beam in a pupil plane;
• a support structure for supporting a patterning structure, the illumination system defining an angle dependent intensity distribution of the beam at the patterning structure dependent on the position dependent intensity distribution in the pupil plane;
• a substrate table for holding a substrate;
• a projection system for projecting the patterned beam onto a target portion of the substrate;
• a beam splitter positioned in a path of the projection beam during operation of the lithographic apparatus, the beam splitter splitting off an auxiliary beam;
• a detector with a detection element disposed in a path of the auxiliary beam so as to detect information about a position dependent intensity distribution corresponding to the pupil plane;
• a light conducting rod having reflecting side walls to reduce position dependence of the intensity distribution of the beam, the rod being disposed in the path of the projection beam between the pupil plane and a first image plane of the pupil plane;
• and
• at least one optical element configured to image the pupil plane onto the first image plane of the pupil plane,
• wherein the beam splitter is positioned downstream of the light conducting rod.