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In this paper, results from the completed projection optic box (PO, POB) systems are presented. The achieved single pass transmitted wavefront (CA – 30 cycles/aperture) on the first two systems was better than 0.25nm RMS at the center of the field and < 0.48nm RMS over the 30um x 200um field, less than half of the original specification. The flare, as calculated from the component roughness data, is less than the 5% specification. The paper includes a presentation of results from the component mirror metrology, the multilayer coatings, and the system metrology. To support the tight specifications, the component and system metrology tests required test reproducibility on the order of <50pm. To achieve the high quality wavefront, the optic mounts had to produce very small surface deformation. Also, the precision and stability of the alignment had to be controlled to a few tens of nanometer. The mirror motion is controlled by a hexapod system and the processes and mechanics that were used to align the POB will be described. Results of alignment convergence, wavefront error at the center of the field and over the field, as well as reproducibility are presented. |
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CITATIONS
Cited by 2 scholarly publications and 1 patent.
Wavefronts
Mirrors
Optical fabrication
Optical testing
Optical alignment
Extreme ultraviolet
Reticles
