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 techn ology. On the basis of single-fiber calibrations, the optic when teste d is expected to deliver congruent-to 0.24 mJ/cm2 for a J/2pi sr sourc e pulse at [lambda] = 14 angstrom. Simulations predict that after 40 c m the beam will be uniform to within 4% (3sigma) over a 20 X 20 mm2 fi eld. The local divergence of the beam is designed to be 5.0+/-5% mrad full width at half-maximum for optimum processing latitude. Because th e divergent beam from a point source projects out-of-plane mask-wafer gap variations into lateral printing errors, collimation will be requi red if overlay requirements for future sub-0.25 mum devices are to be achieved. The predicted throughput advantage for this collimator compa red to an uncollimated source removed to a sufficient distance to meet the requirements for first-generation ultra-large-scale integration i s a factor of congruent-to 5, assuming a 3sigma = 1 mum gap error.