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Proceedings Paper

A study of process window capabilities for two-dimensional structures under double exposure condition
Author(s): Qiang Wu; Peng Wu; Jun Zhu; Hua Ding; Xin Li; Changjiang Sun; Chaoqun Peng
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Paper Abstract

Among the three candidate approaches for 32 nm, the double exposure/patterning with 1.35 NA immersion, the high refractive index immersion, and the extremely ultra violet (EUV) lithography, the easiest approach seems to be the double exposure/patterning method at an effective numerical aperture (NA) of 1.35. However, the design and optimization of the process, such as, the choice of illumination condition, the choice of a photoresist, and the design of an optical proximity correction (OPC) strategy for both the singly and doubly exposed patterns still need to be developed. In this paper, we will focus on the finding of a suitable methodology in the printing of two-dimensional (2D) structures under the double exposure and single development scheme since it is the easiest and there is virtually no overlay concern. We have used a 248 nm exposure tool and a well-chosen photoresist to study the photo performance parameters in the merge of two photo exposures. At a numerical aperture (NA) around 0.7, the minimum ground rule we can achieve is 110 nm, similar to the one for a 75 nm logic-like process with minimum pitch of 220 nm. In the experiment, the single exposure structures are limited to pitches wider than 440 nm. In this paper, we will present a study on main process window parameters, such as, exposure latitude (EL), depth of focus (DOF), and mask error factor (MEF) for a typical 2D structure, the isolated opposing line end. We will demonstrate a nearly analytical method for the description of the line end shortening.

Paper Details

Date Published: 26 March 2007
PDF: 10 pages
Proc. SPIE 6520, Optical Microlithography XX, 65202O (26 March 2007); doi: 10.1117/12.712089
Show Author Affiliations
Qiang Wu, Shanghai Huahong NEC Electronics Co., Ltd. (China)
Peng Wu, Shanghai Huahong NEC Electronics Co., Ltd. (China)
Jun Zhu, Shanghai Integrated Circuit Research and Development Ctr. (China)
Hua Ding, Shanghai Huahong NEC Electronics Co., Ltd. (China)
Xin Li, Shanghai Huahong NEC Electronics Co., Ltd. (China)
Changjiang Sun, Shanghai Huahong NEC Electronics Co., Ltd. (China)
Chaoqun Peng, Shanghai Huahong NEC Electronics Co., Ltd. (China)

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

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