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Proceedings Paper

Pattern deformation induced from intensity-unbalanced off-axis illumination
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Paper Abstract

Currently it is very popular to use off-axis illumination technique for higher resolution with wider depth of focus. However there are several problems in the technique, one of which is deterioration of image quality induced by the non- uniform effective source distribution. If the intensity distribution on the illumination aperture lacks of spatial symmetry, each diffraction order beam impinging on the wafer surface has angularly asymmetric distribution. This makes the optical system have pattern size dependent telecentricity error. For a simple line or grouped lines it gives rise to only the pattern displacement with defocus which can hardly be detected unless there are any reference. But the periodic island type patterns which have discrete features and multiple pitch components in one direction can be bent and deformed asymmetrically with defocus. Asymmetric imaging for island type patterns gives rise to also the pattern CD asymmetry with defocus. We present schematic explanation of the effects of non-uniform effective source and the simulation result. We also investigated the phenomena in a high density DRAM cell active layer of 460 nm minimum pitch and characterized it by various approach.

Paper Details

Date Published: 7 July 1997
PDF: 12 pages
Proc. SPIE 3051, Optical Microlithography X, (7 July 1997); doi: 10.1117/12.275980
Show Author Affiliations
Jin-Ha Kim, Samsung Electronics Co., Ltd. (South Korea)
Seok-Hwan Oh, Samsung Electronics Co., Ltd. (South Korea)
Dong-Seon Lee, Samsung Electronics Co., Ltd. (South Korea)
Jeong-Ho Yeo, Samsung Electronics Co., Ltd. (South Korea)
Yong Hun Yu, Samsung Electronics Co., Ltd. (South Korea)
Jeong-Lim Nam, Samsung Electronics Co., Ltd. (South Korea)

Published in SPIE Proceedings Vol. 3051:
Optical Microlithography X
Gene E. Fuller, Editor(s)

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