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Methods for the synthesis and purification of polycycloalkane candidates for photolithography immersion fluids at 193nm: requirements for removal of oxygen

[+] Author Affiliations
Juan López-Gejo

Columbia University, Department of Chemistry, 3000 Broadway, New York, New York 10027

Joy T. Kunjappu

Brooklyn College of the City University of New York, Chemistry Department, 2900 Bedford Avenue, Brooklyn, New York 11210

Will Conley

Freescale Semiconductor, Centre de Recherche, 870 rue Jean Monnet, Crolles, France

Paul Zimmerman

SEMATECH, Austin, Texas 78741

Nicholas J. Turro

Columbia University, Department of Chemistry, 3000 Broadway, New York, New York 10027

J. Micro/Nanolith. MEMS MOEMS. 6(3), 033003 (September 10, 2007). doi:10.1117/1.2778641
History: Received February 08, 2007; Revised June 06, 2007; Accepted June 12, 2007; Published September 10, 2007
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Cycloalkanes are candidates for immersion fluids because of their potential for low absorption in the 193-nm region and for a high refractive index (RI). We have developed an empirical correlation between refractive index and density of alkanes, which allows a prediction of the best candidates for immersion fluids based on the alkane structure. In particular, the correlation reveals that polycycloalkanes such as perhydrophenanthrene (PHPh) and perhydrodropyrene (PHPy), which have a higher RI than linear or cyclic alkanes, will be excellent candidates for immersion fluids at 193nm. Therefore, PHPh and PHPy were synthesized by exhaustive hydrogenation of phenanthrene and pyrene. However, methods for the purification of the synthesized and commercial alkanes such as cyclodecane (CYD), cyclohexane (CYX), pentane (PNT), and decalin (DEC) are required in order to determine the actual absorption of candidates at 193nm. The presence of an absorbing impurity at 193nm can cause the premature elimination of otherwise excellent potential candidates. A rather subtle impurity is molecular oxygen, which does not itself absorb at 193nm, but which forms complexes with alkanes that do absorb at 193nm. In this case, the “impurity” is readily eliminated by simple purging with nitrogen or argon gas.

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© 2007 Society of Photo-Optical Instrumentation Engineers

Citation

Juan López-Gejo ; Joy T. Kunjappu ; Will Conley ; Paul Zimmerman and Nicholas J. Turro
"Methods for the synthesis and purification of polycycloalkane candidates for photolithography immersion fluids at 193nm: requirements for removal of oxygen", J. Micro/Nanolith. MEMS MOEMS. 6(3), 033003 (September 10, 2007). ; http://dx.doi.org/10.1117/1.2778641


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