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Journal of Micro/Nanolithography, MEMS, and MOEMS

Vectorial mask optimization methods for robust optical lithography
Author(s): Xu Ma; Yanqiu Li; Xuejia Guo; Lisong Dong
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Paper Abstract

Continuous shrinkage of critical dimension in an integrated circuit impels the development of resolution enhancement techniques for low k1 lithography. Recently, several pixelated optical proximity correction (OPC) and phase-shifting mask (PSM) approaches were developed under scalar imaging models to account for the process variations. However, the lithography systems with larger-NA (NA > 0.6) are predominant for current technology nodes, rendering the scalar models inadequate to describe the vector nature of the electromagnetic field that propagates through the optical lithography system. In addition, OPC and PSM algorithms based on scalar models can compensate for wavefront aberrations, but are incapable of mitigating polarization aberrations in practical lithography systems, which can only be dealt with under the vector model. To this end, we focus on developing robust pixelated gradient-based OPC and PSM optimization algorithms aimed at canceling defocus, dose variation, wavefront and polarization aberrations under a vector model. First, an integrative and analytic vector imaging model is applied to formulate the optimization problem, where the effects of process variations are explicitly incorporated in the optimization framework. A steepest descent algorithm is then used to iteratively optimize the mask patterns. Simulations show that the proposed algorithms can effectively improve the process windows of the optical lithography systems.

Paper Details

Date Published: 15 November 2012
PDF: 16 pages
J. Micro/Nanolith. MEMS MOEMS 11(4) 043008 doi: 10.1117/1.JMM.11.4.043008
Published in: Journal of Micro/Nanolithography, MEMS, and MOEMS Volume 11, Issue 4
Show Author Affiliations
Xu Ma, Beijing Institute of Technology (China)
Yanqiu Li, Beijing Institute of Technology (China)
Xuejia Guo, Beijing Institute of Technology (China)
Lisong Dong, Beijing Institute of Technology (China)

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