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Proceedings Paper

Optimizing the lithography model calibration algorithms for NTD process
Author(s): C. M. Hu; Fred Lo; Elvis Yang; T. H. Yang; K. C. Chen
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Paper Abstract

As patterns shrink to the resolution limits of up-to-date ArF immersion lithography technology, negative tone development (NTD) process has been an increasingly adopted technique to get superior imaging quality through employing bright-field (BF) masks to print the critical dark-field (DF) metal and contact layers. However, from the fundamental materials and process interaction perspectives, several key differences inherently exist between NTD process and the traditional positive tone development (PTD) system, especially the horizontal/vertical resist shrinkage and developer depletion effects, hence the traditional resist parameters developed for the typical PTD process have no longer fit well in NTD process modeling. In order to cope with the inherent differences between PTD and NTD processes accordingly get improvement on NTD modeling accuracy, several NTD models with different combinations of complementary terms were built to account for the NTD-specific resist shrinkage, developer depletion and diffusion, and wafer CD jump induced by sub threshold assistance feature (SRAF) effects. Each new complementary NTD term has its definite aim to deal with the NTD-specific phenomena. In this study, the modeling accuracy is compared among different models for the specific patterning characteristics on various feature types. Multiple complementary NTD terms were finally proposed to address all the NTD-specific behaviors simultaneously and further optimize the NTD modeling accuracy. The new algorithm of multiple complementary NTD term tested on our critical dark-field layers demonstrates consistent model accuracy improvement for both calibration and verification.

Paper Details

Date Published: 15 March 2016
PDF: 8 pages
Proc. SPIE 9780, Optical Microlithography XXIX, 978018 (15 March 2016); doi: 10.1117/12.2216049
Show Author Affiliations
C. M. Hu, Macronix International Co., Ltd. (Taiwan)
Fred Lo, Macronix International Co., Ltd. (Taiwan)
Elvis Yang, Macronix International Co., Ltd. (Taiwan)
T. H. Yang, Macronix International Co., Ltd. (Taiwan)
K. C. Chen, Macronix International Co., Ltd. (Taiwan)

Published in SPIE Proceedings Vol. 9780:
Optical Microlithography XXIX
Andreas Erdmann; Jongwook Kye, Editor(s)

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