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Journal of Micro/Nanolithography, MEMS, and MOEMS

Inverse lithography for 45-nm-node contact holes at 1.35 numerical aperture
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Paper Abstract

Inverse lithography technology (ILT) is a procedure that optimizes the mask layout to produce an image at the wafer with the targeted aerial image. For an illumination condition optimized for dense pitches, ILT inserts model-based subresolution assist features (AF) to improve the imaging of isolated features. ILT is ideal for random contact hole patterns, in which the AF are not at intuitive locations. The raw output of ILT consists of very complex smooth shapes that must be simplified for an acceptable mask write time. It is challenging for ILT to quickly converge to the ideal pattern as well as to simplify the pattern to one that can be manufactured quickly. ILT has many parameters that effect process latitude, background suppression, conversion run time, and mask write time. In this work, an optimization procedure is introduced to find the best tradeoff between image quality and run time or write time. A conversion run time reduction of 4.7× is realized with the outcome of this optimization procedure. Simulations of mask write time quantify the ability of ILT to be used for full chip applications. The optimization procedure is also applied to alternate mask technologies to reveal their advantages over commonly used 6% attenuated phase shift masks.

Paper Details

Date Published: 1 October 2009
PDF: 9 pages
J. Micro/Nanolith. 8(4) 043001 doi: 10.1117/1.3263702
Published in: Journal of Micro/Nanolithography, MEMS, and MOEMS Volume 8, Issue 4
Show Author Affiliations
Monica Laurel Kempsell, Mentor Graphics Corp. (United States)
Eric Hendrickx, IMEC (Belgium)
Alexander V. Tritchkov, Mentor Graphics Corp. (United States)
Kyohei Sakajiri, Mentor Graphics Corp. (United States)
Kenichi Yasui, NuFlare Technology, Inc. (Japan)
Susuki Yoshitake, NuFlare Technology, Inc. (Japan)
Yuri Granik, Mentor Graphics Corp. (United States)
Geert Vandenberghe, IMEC (Belgium)
Bruce W. Smith, Rochester Institute of Technology (United States)


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