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Journal of Micro/Nanolithography, MEMS, and MOEMS

Depth of focus enhancement for sub-110-nm technology by using KrF double-exposure lithography
Author(s): Liang Zhu; Yingchun Zhang; Yili Gu; Steve Yang; Xiaohui Kang
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Paper Abstract

Traditional double-exposure lithography (DEL) or double-patterning lithography (DPL) methodologies stem most from the resolution enhancement standpoint. A single mask with high feature densities is split into two exposure steps, each with lower feature densities that can be easily resolved. The DEL is proposed as the process window enhancement technology for sub-110-nm technology. Features with sparse pitches are printed by a first step of dense pitch exposures and a second exposure with dummy features removed. The pattern decomposition strategy described is similar to that of subresolution assisting features (SRAF). So it is compatible with the traditional rule-based SRAF implementation methodology. By comparing the depth of focus (DOF) of the 110-nm lithography process between the single exposure and the double exposure, it is found that the DOF for marginal features is extended by using double-exposure methodology, and thus extends the capability of KrF exposure tools. Furthermore, the link between the overlay performance and the overlap of the second exposure's trim slots over the first exposure is studied. The results show that the overlay control is within the KrF scanner capability. As a further study, the proposed double-exposure methodology for the 90-nm lithography process is evaluated.

Paper Details

Date Published: 1 April 2009
PDF: 8 pages
J. Micro/Nanolith. 8(2) 023008 doi: 10.1117/1.3155515
Published in: Journal of Micro/Nanolithography, MEMS, and MOEMS Volume 8, Issue 2
Show Author Affiliations
Liang Zhu, Grace Semiconductor Manufacturing Corp. (China)
Yingchun Zhang, Grace Semiconductor Manufacturing Corp. (China)
Yili Gu, Grace Semiconductor Manufacturing Corp. (China)
Steve Yang, Grace Semiconductor Manufacturing Corp. (China)
Xiaohui Kang, Mentor Graphics Shanghai Electronic Technology Co. (China)

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