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Proceedings Paper

Resolution enhancement techniques in optical lithography: It's not just a mask problem
Author(s): Lars W. Liebmann
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Paper Abstract

Over the past decade, optical lithography's k1 factor has been continuously eroding despite aggressive improvements in exposure wavelength and numerical aperture. To compensate for the increased difficulty in maintaining adequate process windows at smaller k1's, lithographers have gradually introduced mild resolution enhancement techniques (RETs) such as the use of optical proximity correction (OPC) and attenuated phase shifted mask enhanced lithography (attPSM). The penetration of the k1=0.5 barrier with the 180nm technology node forced serious consideration of strong resolution enhancement techniques such as the use of sub-resolution assist features (SRAFs) with off-axis illumination (OAI), and alternating phase shifted mask enhanced lithography (altPSM). Penetrating into the deep-sub-k1=0.5 lithography regime for the 130nm and 100nm technology nodes requires broad implementation of these strong RETs in well integrated lithography solutions. After briefly reviewing the history and challenges associated with OPC, this paper will discuss the fundamental concepts and theoretical resolution limits of altPSM and SRAF followed by some experimental results. The paper will then review the challenges facing the implementation of SRAF and altPSM in deep-sub-k1=0.5 production lithography.

Paper Details

Date Published: 5 September 2001
PDF: 10 pages
Proc. SPIE 4409, Photomask and Next-Generation Lithography Mask Technology VIII, (5 September 2001); doi: 10.1117/12.438332
Show Author Affiliations
Lars W. Liebmann, IBM Microelectronics (United States)


Published in SPIE Proceedings Vol. 4409:
Photomask and Next-Generation Lithography Mask Technology VIII
Hiroichi Kawahira, Editor(s)

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