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Optical Engineering

Fabrication error analysis for diffractive optical elements used in a lithography illumination system
Author(s): Jian Wang; Fang Zhang; Qiang Song; Aijun Zeng; Jing Zhu; Huijie Huang
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Paper Abstract

With the constant shrinking of printable critical dimensions in photolithography, off-axis illumination (OAI) becomes one of the effective resolution-enhancement methods facing these challenges. This, in turn, is driving much more strict requirements, such as higher diffractive efficiency of the diffractive optical elements (DOEs) used in the OAI system. Since the design algorithms to optimize DOEs’ phase profile are improved, the fabrication process becomes the main limiting factor leading to energy loss. Tolerance analysis is the general method to evaluate the fabrication accuracy requirement, which is especially useful for highly specialized deep UV applications with small structures and tight tolerances. A subpixel DOE simulation model is applied for tolerance analysis of DOEs by converting the abstractive fabrication structure errors into quantifiable subpixel phase matrices. Adopting the proposed model, four kinds of fabrication errors including misetch, misalignment, feature size error, and feature rounding error are able to be investigated. In the simulation experiments, systematic fabrication error studies of five typical DOEs used in 90-nm scanning photolithography illumination system are carried out. These results are valuable in the range of high precision DOE design algorithm and fabrication process optimization.

Paper Details

Date Published: 13 April 2015
PDF: 8 pages
Opt. Eng. 54(4) 045102 doi: 10.1117/1.OE.54.4.045102
Published in: Optical Engineering Volume 54, Issue 4
Show Author Affiliations
Jian Wang, Shanghai Institute of Optics and Fine Mechanics (China)
Univ. of the Chinese Academy of Sciences (China)
Fang Zhang, Shanghai Institute of Optics and Fine Mechanics (China)
Univ. of the Chinese Academy of Sciences (China)
Qiang Song, Shanghai Institute of Optics and Fine Mechanics (China)
Univ. of the Chinese Academy of Sciences (China)
Aijun Zeng, Shanghai Institute of Optics and Fine Mechanics (China)
Jing Zhu, Shanghai Institute of Optics and Fine Mechanics (China)
Huijie Huang, Shanghai Institute of Optics and Fine Mechanics (China)


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