High Speed, High Accuracy Stage for Advanced Lithography. Phase I
Final rept. 20 Oct 97-15 Jun 98
OPTRA INC TOPSFIELD MA
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The overall program goal is to develop an integrated stage and metrology system for microlithography, based on the use of an XY encoder grid, meeting the following specifications a 12 x 12 coverage, b accuracy of - 2.5nm or better, c operable at a speed of 1 metersec, and d active control of all 6 degrees of freedom. To this end, the Phase I program had goals of 1 finding one or more suppliers of high-accuracy grids 2 grid-based measurement repeatability of - 2.5nm or better, 3 ability to work at speeds of up to 1 metersec, and 4 development of a short-range optical sensor for servo control of the nominally fixed degrees of freedom Z, thetax, and thetay. With the exception of the velocity specification, these Phase I goals were all met. We were able to work at velocities of up to 790mmsec, and can readily get to 1 metersec by upgrading the speed of the ADs in our phase processor. Measurement repeatability of - 2.5nm was achieved in an environment where the turbulence-limited repeatability of a laser interferometer was on the order of 10nm to 20nm. We found the Etec ALTA laser-writer to be the best machine for making accurate grids.
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