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Proceedings Paper

Benefits and trade-offs of global source optimization in optical lithography
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Paper Abstract

Source optimization in optical lithography has been the subject of increased exploration in recent years [1-4], resulting in the development of multiple techniques including global optimization of process window [4]. The performance advantages of source optimization have been demonstrated through theory, simulation, and experiment. This paper will emphasize global optimization of sources over multiple patterns, e.g. co-optimization of critical SRAM cells and the critical pitches of random logic, and implement global source optimization into current resolution enhancement techniques (RETs). The effect on optimal source due to considering multiple patterns is investigated. We demonstrate that optimal source for limited patterns does work for a large clip of layout. Through theoretical analysis and simulations, we explain that only critical patterns and/or critical combinations of patterns determine the final optimal source; for example those patterns that contain constraints which are active in the solution. Furthermore, we illustrate, through theory and simulation, that pixelated sources have better performance than generic sources and that in general it is impossible for generic sources to construct a truly optimal solution. Sensitivity, tool matching, and lens heating issues for pixelated sources are also discussed in this paper. Finally, we use a RETs example with wafer data to demonstrate the benefits of global source optimization.

Paper Details

Date Published: 16 March 2009
PDF: 12 pages
Proc. SPIE 7274, Optical Microlithography XXII, 72740C (16 March 2009); doi: 10.1117/12.814305
Show Author Affiliations
Kehan Tian, IBM Semiconductor Research and Development Ctr. (United States)
Azalia Krasnoperova, IBM Semiconductor Research and Development Ctr. (United States)
David Melville, IBM Thomas J. Watson Research Ctr. (United States)
Alan E. Rosenbluth, IBM Thomas J. Watson Research Ctr. (United States)
Dario Gil, IBM Thomas J. Watson Research Ctr. (United States)
Jaione Tirapu-Azpiroz, IBM Semiconductor Research and Development Ctr. (United States)
Kafai Lai, IBM Semiconductor Research and Development Ctr. (United States)
Saeed Bagheri, IBM Semiconductor Research and Development Ctr. (United States)
Chia-chen Chen, IBM Semiconductor Research and Development Ctr. (United States)
Bradley Morgenfeld, IBM Semiconductor Research and Development Ctr. (United States)


Published in SPIE Proceedings Vol. 7274:
Optical Microlithography XXII
Harry J. Levinson; Mircea V. Dusa, Editor(s)

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