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Title: Customized illumination shapes for 193nm immersion lithography
Authors: Moh, L.L.
Gek, S.C.
Qunying, L.
Cho, J.T. 
Chenggen, Q. 
Keywords: Annular illumination
Dipole illumination
Forbidden pitch
Immersion lithography
Off axis illumination
Partial coherent imaging
Resolution enhancement
Issue Date: 2008
Citation: Moh, L.L., Gek, S.C., Qunying, L., Cho, J.T., Chenggen, Q. (2008). Customized illumination shapes for 193nm immersion lithography. Proceedings of SPIE - The International Society for Optical Engineering 6924 : -. ScholarBank@NUS Repository.
Abstract: In this paper, a study on customized illumination shape configurations as resolution enhancement for 45nm technology node will be presented. Several new source shape configurations will be explored through simulation based on 193nm immersion lithography on 6% Attenuated Phase Shift Mask. Forbidden pitch effect is commonly encountered in the application of off axis illumination (OAI). The illumination settings are often optimized to allow maximum process window for a pitch. This is done by creating symmetrical distribution of diffraction order on the pupil plane. However, at other pitch, the distribution of diffraction order on the pupil plane results in severe degradation in image contrast and results in significant critical dimension (CD) fluctuation. The problematic pitch is often known as forbidden pitch. It has to be avoided in the design and thus limited the pitch range to be imaged for particular illumination. An approach to modify off axis illumination to minimize the effect of forbidden pitch is explored in this study. The new customized shape for one dimensional line and space pattern is modified from current off axis illumination. Simulation study is done to evaluate the performance some customized shapes. The extent of CD fluctuation and CD through pitch uniformity is analyzed to determine the performance enhancement of the new illumination shapes. From simulation result, the proposed modification have significantly improved the through pitch performance and minimized the effect of forbidden pitch.
Source Title: Proceedings of SPIE - The International Society for Optical Engineering
ISBN: 9780819471093
ISSN: 0277786X
DOI: 10.1117/12.772441
Appears in Collections:Staff Publications

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