28 June 2005 Quartz etch process for alternating aperture phase shift masks (alt-APSM)
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Proceedings Volume 5853, Photomask and Next-Generation Lithography Mask Technology XII; (2005) https://doi.org/10.1117/12.617095
Event: Photomask and Next Generation Lithography Mask Technology XII, 2005, Yokohama, Japan
Abstract
The quartz dry etch is a critical step in the manufacture of Alternating Aperture Phase Shift masks (alt-APSM). In order to maintain uniform phase shift across the mask, the etch depth uniformity has to be strictly controlled. Both the radial and linear components of non-uniformity have to be minimized. The Mask Etcher IV developed at Unaxis USA reduces both the components of non-uniformity using unique hardware adjustments. Using a fluorocarbon based chemistry, etch depth variations between different feature sizes is also minimized. With good etch depth linearity, phase shift does not vary with feature size. To achieve this, etched quartz structures need to have good selectivity to resist / chrome and vertical sidewalls. Etch depth uniformity was measured using an n&k1700 RT and etch depth linearity was measured using an AFM. Etched quartz structure morphologies are observed using a SEM. After preliminary screening experiments, an optimized hardware suite and process conditions that produce good etch depth uniformity, linearity and quartz profiles with vertical sidewalls and minimum microtrenching is determined.
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Sunil Srinivasan, Sunil Srinivasan, Russ Westerman, Russ Westerman, Jason Plumhoff, Jason Plumhoff, Dave Johnson, Dave Johnson, Chris Constantine, Chris Constantine, } "Quartz etch process for alternating aperture phase shift masks (alt-APSM)", Proc. SPIE 5853, Photomask and Next-Generation Lithography Mask Technology XII, (28 June 2005); doi: 10.1117/12.617095; https://doi.org/10.1117/12.617095
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