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Proceedings Paper

60nm half pitch contact layer printing: exploring the limits at 1.35NA lithography
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Paper Abstract

The ever increasing NA to meet the stringent requirements on pitch and litho target does not come without a price. In particular for the printing of contact layers, the toll is taken in terms of decreased process latitudes and CD uniformity. Depending on the specific contact layer design, it has become increasingly important to choose the most adequate resolution enhancement technique. At the ultimate NA of 1.35, depth of focus through pitch has become a key factor, and values in the order of 100-120nm are the painful truth imposed by physics. In this paper, the attention goes to through-pitch contact imaging, with the attempt to achieve half pitches around 60nm. Thereby, the main focus lies on the relation between source shape and minimum achievable k1. In addition, the pro's and con's of two options for throughpitch process latitude enhancement are considered. These options are firstly the effect of assist feature placement in combination with off-axis illumination, and secondly the application of the Focus Drilling technique. Finally, the different contributions to contact hole CD non-uniformity are addressed.

Paper Details

Date Published: 7 March 2008
PDF: 12 pages
Proc. SPIE 6924, Optical Microlithography XXI, 69243A (7 March 2008); doi: 10.1117/12.772596
Show Author Affiliations
Joost Bekaert, IMEC vzw (Belgium)
Eric Hendrickx, IMEC vzw (Belgium)
Geert Vandenberghe, IMEC vzw (Belgium)

Published in SPIE Proceedings Vol. 6924:
Optical Microlithography XXI
Harry J. Levinson; Mircea V. Dusa, Editor(s)

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