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Journal of Micro/Nanolithography, MEMS, and MOEMS

Microfluidic simulations for immersion lithography
Author(s): Alexander C. Wei; Gregory F. Nellis; Amr Y. Abdo; Roxann L. Engelstad; Cheng-Fu Chen; Michael Switkes; Mordechai Rothschild
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Paper Abstract

The premise behind immersion lithography is to improve resolution by increasing the index of refraction in the space between the final projection lens of an exposure system and the device wafer by inserting a high-index liquid in place of the low-index air that currently fills the gap. We present a preliminary analysis of the fluid flow characteristics of a liquid between the lens and the wafer. The objectives of this feasibility study are to identify liquid candidates that meet the fluid mechanical requirements and to verify modeling tools for immersion lithography. The filling process was analyzed to simplify the problem and identify important fluid properties and system parameters. Two-dimensional computational fluid dynamics (CFD) models of the fluid between the lens and the wafer are developed and used to investigate a passive technique for filling this gap, in which a liquid is dispensed onto the wafer as a puddle, and then the wafer and liquid move under the lens. Numerical simulations include a parametric study of the key dimensionless groups influencing the filling process, and an investigation of the effects of the fluid/wafer and fluid/lens contact angles and wafer direction. The model results are compared with experimental measurements.

Paper Details

Date Published: 1 January 2004
PDF: 7 pages
J. Micro/Nanolith. 3(1) doi: 10.1117/1.1632500
Published in: Journal of Micro/Nanolithography, MEMS, and MOEMS Volume 3, Issue 1
Show Author Affiliations
Alexander C. Wei, Univ. of Wisconsin/Madison (United States)
Gregory F. Nellis, Univ. of Wisconsin/Madison (United States)
Amr Y. Abdo, Univ. of Wisconsin/Madison (United States)
Roxann L. Engelstad, Univ. of Wisconsin/Madison (United States)
Cheng-Fu Chen, Univ. of Alaska Fairbanks (United States)
Michael Switkes, MIT Lincoln Lab. (United States)
Mordechai Rothschild, Massachusetts Institute of Technology (United States)

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