Our GCA wafer stepper is an i-line (365 nm) step and repeat exposure tool for doing lithography that requires high resolution and/or critical alignment. The system has been modified to accept piece parts (down to ~15 mm x 15 mm) up to 6” diameter wafers using manual wafer loading. The maximum square die size is 14.8mm x 14.8mm. The system has an Olympus 2142 (N.A. = 0.42) lens that reduces the mask image by 5 x and gives an ultimate resolution of ~ 0.5 um in the center of the lens field. The system can easily produce 0.7 um isolated lines across the entire field. Autofocus is used to determine the sample surface relative to the lens, making the focus stable and repeatable for different thickness of wafer. The stages are controlled by stepper motors and laser interferometers. Using the global, manual alignment, better than 0.25 um alignment error is achievable. Using the DFAS local alignment system, alignment error better than 0.15 um is achieved. With the 350 W Hg arc lamp, we get approximately 180 mW/cm² of i-line intensity at the wafer.
Contact Tom Reynolds to find out more about access and training for the Nanofabrication Facility.