<title>Micrascan III: 0.25-um resolution step-and-scan system</title>

Abstract

Catadioptric step-and-scan lithography offers specific advantages over step-and-repeat all-refractive (dioptric) systems as resolution requirements drive to 0.25pm in volume production. For the Micrascan family ofstep-and-scan tools this step in the evolutionary path from 0.35.tm to 0.25.tm has involved changes to both the projection optics and illumination system.

Multi-Repeated Projection Lithography for High-Precision Linear Scale Based on Average Homogenization Effect

“…In linear scale projection lithography, in addition to the above problems, the main factors that affect the accuracy of lithography include the static and dynamic positioning accuracy, the parallelism of the focal plane and photoresist plane on the scale, and the uniformity of light intensity distribution. Several methods have adopted the principle of splicing together, in which the patterns are adjacent and printed accurately on the wafer at an accurate distance, such as the step-and-repeat method [ 6 ], single-step method [ 7 ], and step-and-scan method [ 8 , 9 ], where the x - and y -direction positioning accuracies are not high. The hexagonal seamless scanning exposure method behaves the advantage for fabrication of large area grating than stitching exposure method in steppers [ 10 ], adjacent hexagonal scans overlap partially and integrated doses from successive scans produce uniform exposure over the whole panel, however, we adopt adjacent quadrangular scans overlap by integer times of pitch theoretically, the pitch errors are homogenized by multi-repeated exposure of different position grating on the mask.…”

Level-specific lithography optimization for 1-Gb DRAM

“…For the first time manufacture occurs at a factor 1 of less than 0.5. Even with state-of-the-art production-worthy high numerical aperture NA deep-UV ( nm) step-and-scan exposure systems [1], [2], the 175-nm critical dimension (CD) corresponds to and the 150 nm to . Processing with conventional lithography 2 at such low factors results in inadequate process latitude; none of the critical levels of a 1-Gb DRAM design [3] shown in Fig.…”

“…Simulation accounting for aerial image formation and the effects of photoresist development [24] was first used to identify optimal lithography conditions for each level based on a quantity called the "total window." Experiments were then carried out on 0.60-NA 248-nm exposure systems [1], [2] to quantify the actual process latitude improvement afforded by the optical enhancement techniques.…”

“…The smaller the k factor, the more difficult the process. General belief holds that k > 0:7 for a robust process 2. Conventional lithography is comprised of using chromium-on-glass photomasks and conventional illumination 3.…”