Journal of Vacuum Science & Technology B, Vol.11, No.6, 3003-3007, 1993
Polycapillary Collimator for Point-Source Proximity X-Ray-Lithography
A full-scale prototype collimator suitable for point source proximity x-ray lithography has been constructed using polycapillary fiber technology. On the basis of single-fiber calibrations, the optic when tested is expected to deliver congruent-to 0.24 mJ/cm2 for a J/2pi sr source pulse at [lambda] = 14 angstrom. Simulations predict that after 40 cm the beam will be uniform to within 4% (3sigma) over a 20 X 20 mm2 field. The local divergence of the beam is designed to be 5.0+/-5% mrad full width at half-maximum for optimum processing latitude. Because the divergent beam from a point source projects out-of-plane mask-wafer gap variations into lateral printing errors, collimation will be required if overlay requirements for future sub-0.25 mum devices are to be achieved. The predicted throughput advantage for this collimator compared to an uncollimated source removed to a sufficient distance to meet the requirements for first-generation ultra-large-scale integration is a factor of congruent-to 5, assuming a 3sigma = 1 mum gap error.