The models based on pixelized representation of the photomask have been employed by several authors in order to provide the systematic framework for design of photomask patterns resulting in images with desired optimal properties. One possibility to directly implement such pixel-based optimal mask patterns arises in Optical Maskless Lithography (OML). In one implementation of OML, spatial light modulators (SLMs) are used instead of the photomask. Each SLM may have millions of pixels that can individually change their optical properties utilizing one or the other physical modulation principle (e.g. pistoning micro-mirror pixels or tilting micro-mirror pixels). One important question, applicable to both SLMs used in OML and pixelized photomasks, is: how well is a particular pixel modulation principle suited to obtain the optimal image? We discuss the ways to answer this question, derived from the new methodology of OML rasterization algorithms. The illustrating examples are presented for traditional photomasks (AttPSM) and the SLMs with pistoning micro-mirror pixels. Based on this analysis, we present new examples demonstrating the concept and advantages of "truly maskless" optical maskless lithography.

Date Published: 20 October 2006
PDF: 12 pages
Proc. SPIE 6349, Photomask Technology 2006, 63490R (20 October 2006); doi: 10.1117/12.686518

Published in SPIE Proceedings Vol. 6349:
Photomask Technology 2006
Patrick M. Martin; Robert J. Naber, Editor(s)