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Proceedings Paper

Method to devise multiphase complex mask in submicron lithography
Author(s): Xiangang Luo; HanMin Yao
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Paper Abstract

In our work, we address the problem of design of phase mask for arbitrary two-dimensional patterns. Because of the physical limitations of the projection lithography system, a set of constraints on the class of images at the output is induced by the system. That is to say, it is not possible to generate patterns with arbitrarily sharp corners at the output of a stepper since the optical system is band-limited and the etching process is nonlinear. To overcome this, our approach is to devise a set of specifications for the output image, so that designed input mask satisfy the output's specifications as much as possible. A new method based on alternating projections to design pre-distorted mask has been proposed. First, we decompose the partially coherent imaging system into a set of coherent approximations. Then, we propose an optimization algorithm for designing phase shifting masks. In our algorithm we define two sets and two corresponding operators according to the system band-limited characteristic and etching process. Finally by applying the alternating projections onto the two sets, we obtain mask with continuously varying magnitude and phase. At last we propose a quantification method to fabricate mask to do experiments. In our experiments, the resolution enhancement is obvious and the proximity effects are decreased.

Paper Details

Date Published: 30 December 1999
PDF: 8 pages
Proc. SPIE 3873, 19th Annual Symposium on Photomask Technology, (30 December 1999); doi: 10.1117/12.373295
Show Author Affiliations
Xiangang Luo, Institute of Optics and Electronics (China)
HanMin Yao, Institute of Optics and Electronics (China)

Published in SPIE Proceedings Vol. 3873:
19th Annual Symposium on Photomask Technology
Frank E. Abboud; Brian J. Grenon, Editor(s)

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