Multifield sub-5nm overlay in imprint lithography


P. Ajay, Cherala, A., Yin, B. A., Moon, E. E., Pease, F. R., and Sreenivasan, S. V., “Multifield sub-5nm overlay in imprint lithography,” Journal of Vacuum Science & Technology B, vol. 34, no. 061605, 2016.


One significant advantage of imprint lithography (IL) over photolithography is that the field size is not limited optically, and so, throughput can be very high (>100 cm(2)/s). But, in applications requiring precise (sub-5nm) overlay, the field size is limited by the distortion (between template and wafer) to about the same field size (26 x 33mm) as employed in current photolithographic tools for semiconductor integrated circuits. This reduces the throughput of current IL tools to less than that of current photolithographic tools. Here, the authors have, for the first time, created a multifield (dual and quad fields) nanoscale overlay capability by optimally combining (1) Precision mechanical actuators around the periphery of the fields which can correct for magnification and shear over the whole field, and (2) high resolution intrafield isotropic expansion and contraction using an array of local temperature control units. The authors have developed control algorithms for sub-5 nm overlay precision over up to four fields using thermomechanical simulations, and the authors have experimentally validated the approach. This research has the potential to significantly improve IL throughput without compromising nanoscale overlay. (C) 2016 American Vacuum Society.


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