Apodization Technique for Achieving Uniform Illumination in Storage Ring X-Ray Lithography
Original Publication Date: 1985-Mar-01
Included in the Prior Art Database: 2005-Feb-18
Non-uniformity in the output field intensity of an X-ray beamline (arising, for example, as a result of using an imaging mirror) is corrected by modifying the intensity distribution incident upon the beamline optics with a compensating filter having a spatially varying transmission characteristic. An imaging mirror may be used to increase the exposure intensity in an X-ray lithography beamline at a storage ring (Fig. 1.1). A refocusing ellipsoid (Fig. 1.2) may be used to implement magnification correction ability [*]. A ray-tracing analysis has shown that exposure intensity may be increased by an imaging mirror only by a factor of 3 or 4 before significant horizontal non-uniformity is introduced. The refocusing ellipsoid always introduces more than 10% non-uniformity.