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Proceedings Paper

193-nm CD shrinkage under SEM: modeling the mechanism
Author(s): Andrew Habermas; Dongsung Hong; Matthew F. Ross; William R. Livesay
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Paper Abstract

As photolithography platforms move from 248nm to 193nm resist systems, the industry's established dimension measurement technique (CD-SEM) causes significant shrinkage of the resist structures during measurement. Many studies have been done to characterize this effect and look for the factors that influence / reduce this shrinkage. While numerous anecdotal mechanisms have been proposed to explain the shrinkage, few theoretical / empirical equations have been proposed to connect the observed effects to fundamental mechanisms. Models are proposed relating physical properties (accelerating voltage, photoresist density, resist e-beam film shrinkage) to the commonly observed CD 'hammer test' shrinkage profiles. The validity of the model assumptions is tested via Monte Carlo simulations, FTIR, e-beam curing, SPM and ellipsometry. These models explain the shape of the CD response to repeated measurements (exponential decay curve) and the magnitude of the shrinkage. These models also offer insight into why lower accelerating voltages cause reduced CD shrinkage, although the models predict that accelerating voltage should be a much more dominant parameter for CD shrinkage than literature has shown to date. Mass loss and density changes were also characterized during e-beam cure to check the validity of the model assumptions.

Paper Details

Date Published: 16 July 2002
PDF: 10 pages
Proc. SPIE 4689, Metrology, Inspection, and Process Control for Microlithography XVI, (16 July 2002); doi: 10.1117/12.473436
Show Author Affiliations
Andrew Habermas, Cypress Semiconductor Corp. (United States)
Dongsung Hong, Cypress Semiconductor Corp. (United States)
Matthew F. Ross, Electron Vision Corp. (United States)
William R. Livesay, Electron Vision Corp. (United States)

Published in SPIE Proceedings Vol. 4689:
Metrology, Inspection, and Process Control for Microlithography XVI
Daniel J. C. Herr, Editor(s)

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