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Proceedings Paper

CD-SEM characterization of reticle-level pattern density effects
Author(s): Raymond Yip; Mico Chu; Steven Fu; Dave Castro; Waiman Ng; Geoffrey T. Anderson; Micheal J. Sherrill; Norman Chen; Yao Ching Ku
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Paper Abstract

Three 4X test reticles for 0.15 - 0.18 micrometer lithography are characterized using a critical-dimension scanning electron microscope (CD-SEM). The reticles, which contain metrology cells of isolated and nested lines, are manufactured with an i-line (365 nm) laser patterning tool and wet etch (reticle A), an e-beam patterning tool and dry etch (reticle B), and an e-beam patterning tool and wet etch (reticle C). We investigate the nature of pattern density-induced CD variations by studying groups of metrology cells with systematically varying linewidths and line spacings. The CD bias between nested and isolated lines is a smoothly increasing function of pattern density on reticles B and C. The CD signatures on reticle B exhibit strong microloading and loading signatures related to the plasma etch process. The bias characteristic on reticle A demonstrates a threshold effect, increasing sharply as the space between adjacent nested lines becomes less than approximately 600 nm. Matching images taken with secondary and backscattered electron spectra support the conclusion that the laser write process is resolution-limited at this pattern density. The SEM data is also compared to data from broad-band optical metrology tools to show that the optical response for dense features becomes unreliable when the feature spacing is less than approximately 600 nm.

Paper Details

Date Published: 30 December 1999
PDF: 15 pages
Proc. SPIE 3873, 19th Annual Symposium on Photomask Technology, (30 December 1999); doi: 10.1117/12.373321
Show Author Affiliations
Raymond Yip, KLA-Tencor Corp. (United States)
Mico Chu, KLA-Tencor Corp. Taiwan (Taiwan)
Steven Fu, KLA-Tencor Corp. Taiwan (Taiwan)
Dave Castro, KLA-Tencor Corp. (United States)
Waiman Ng, KLA-Tencor Corp. (United States)
Geoffrey T. Anderson, KLA-Tencor Corp. (United States)
Micheal J. Sherrill, KLA-Tencor Corp. (United States)
Norman Chen, United Microelectronics Corp. (Taiwan)
Yao Ching Ku, United Microelectronics Corp. (Taiwan)

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

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