Share Email Print
cover

Journal of Micro/Nanolithography, MEMS, and MOEMS

Index of refraction of high-index lithographic immersion fluids and its variability
Format Member Price Non-Member Price
PDF $20.00 $25.00

Paper Abstract

We have developed a number of second-generation high-index candidate immersion fluids that exceed the 1.6 refractive index requirement for immersion lithography at 193 nm to replace the water used in first-generation immersion systems. To understand the behavior and performance of different fluid classes, we use spectral index measurements, based on the prism minimum deviation method, to characterize the index dispersion. In addition to fluid absorbance and index requirements, the temperature coefficient of the refractive index is a key parameter. We have used a laser-based Hilger-Chance refractometer system to determine the thermo-optic coefficient (dn/dT) by measuring the index change versus temperature at two different laser wavelengths, 632.8 and 193.4 nm. Also, we determined the batch-to-batch (within a 6-month period), before and after irradiation (at 193.4 nm), before and after air exposure, and before and after resist exposure (image printing test) variations of index and Δn/Δλ. The optical properties of these second-generation immersion fluids mostly compare favorably to water; the ratio of index of refraction at 193.4 nm is 1.644/1.437, the dispersion from d-line (Δn193-d) is 0.160 versus 0.103 and dn/dT at 193.4 is −550×10−6/K vs. −93×10−6/K, respectively.

Paper Details

Date Published: 1 April 2009
PDF: 6 pages
J. Micro/Nanolith. 8(2) 023005 doi: 10.1117/1.3124189
Published in: Journal of Micro/Nanolithography, MEMS, and MOEMS Volume 8, Issue 2
Show Author Affiliations
Min K. Yang, DuPont Co. (United States)
Simon G. Kaplan, National Institute of Standards and Technology (United States)
Roger H. French, DuPont Co. (United States)
John H. Burnett, National Institute of Standards and Technology (United States)


© SPIE. Terms of Use
Back to Top