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Proceedings Paper

Phase-shifted assist feature OPC for sub-45-nm node optical lithography
Author(s): Gi-Sung Yoon; Hee-Bom Kim; Jeung-Woo Lee; Seong-Woon Choi; Woo-Sung Han
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Paper Abstract

Hyper numerical aperture (NA) implemented in immersion exposure system makes the semiconductor business enable to enter sub-45nm node optical lithography. Optical proximity correction(OPC) utilizing SRAF has been an essential technique to control critical dimension (CD) and to enhance across pitch performance in sub-wavelength lithography. Mask lithography, however, is getting more challenging with respect to patterning and processing sub-resolution assist features (SRAFs): the higher aspect ratio of mask structure, the more vulnerable. Mask manufacturing environment for DRAM and Flash becomes harsher mainly due to mask patterning problem especially pattern linearity, which causes pattern broken, inspection issue, and finally CD issue on wafer. When a pattern in relatively isolated pitches has small or large assist features, the assist features may bring unexpected CD or print on wafer. A frequency-preserving assist bar solution is the most preferred one, but it is difficult to realize for opaque assist features due to printability. In this paper, we propose a new type assist feature dubbed "Phase-shifted Assist Bar" to improve process window and to solve the resolution constraint of mask at sub-45nm manufacturing process node. The concept of phase-shift assist bar is applying phase-shift to SRAF realized with trench structure on general mask, such as Binary and Attenuated Phase-Shifted Mask (Att.PSM). The characteristics of phase-shift assist bar are evaluated with rigorous 3D lithography simulation and analyzed through verification mask, which is containing hugely various size and placement of main and assist feature. The analysis of verification mask has been done with aerial image verification tool. This work focuses on the performance of phase-shift assist bar as a promising OPC technique for "immersion era" in terms of resolution enhancement technique, optical proximity correction, and patterning on mask.

Paper Details

Date Published: 27 March 2007
PDF: 10 pages
Proc. SPIE 6520, Optical Microlithography XX, 65201A (27 March 2007); doi: 10.1117/12.712445
Show Author Affiliations
Gi-Sung Yoon, SAMSUNG Electronics Co., Ltd. (South Korea)
Hee-Bom Kim, SAMSUNG Electronics Co., Ltd. (South Korea)
Jeung-Woo Lee, SAMSUNG Electronics Co., Ltd. (South Korea)
Seong-Woon Choi, SAMSUNG Electronics Co., Ltd. (South Korea)
Woo-Sung Han, SAMSUNG Electronics Co., Ltd. (South Korea)

Published in SPIE Proceedings Vol. 6520:
Optical Microlithography XX
Donis G. Flagello, Editor(s)

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