193-nm CD shrinkage under SEM: modeling the mechanism

Andrew Habermas; Dongsung Hong; Matthew F. Ross; William R. Livesay

doi:10.1117/12.473436

16 July 2002 193-nm CD shrinkage under SEM: modeling the mechanism

Andrew Habermas, Dongsung Hong, Matthew F. Ross, William R. Livesay

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Proceedings Volume 4689, Metrology, Inspection, and Process Control for Microlithography XVI; (2002) https://doi.org/10.1117/12.473436
Event: SPIE's 27th Annual International Symposium on Microlithography, 2002, Santa Clara, California, United States

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.

Citation Download Citation

Andrew Habermas, Dongsung Hong, Matthew F. Ross, and William R. Livesay "193-nm CD shrinkage under SEM: modeling the mechanism", Proc. SPIE 4689, Metrology, Inspection, and Process Control for Microlithography XVI, (16 July 2002); https://doi.org/10.1117/12.473436

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