19 March 2015 Low-LER tin carboxylate photoresists using EUV
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Pure thin films of organotin compounds have been lithographically evaluated using extreme ultraviolet lithography (EUVL, 13.5 nm). Twenty-one compounds of the type R2Sn(O2CR’)2 were spin-coated from solutions in toluene, exposed to EUV light, and developed in organic solvents. Exposures produced negative-tone contrast curves and dense-line patterns using interference lithography. Contrast-curve studies indicated that the Emax values were linearly related to molecular weight when plotted separately depending upon the hydrocarbon group bound directly to tin (R = butyl, phenyl and benzyl). Additionally, Emax was found to be linearly related to free radical stability of the hydrocarbon group bound directly to tin. Dense-line patterning capabilities varied, but two resists in particular show exceptionally good line edge roughness (LER). A resist composed of an amorphous film of (C6H5CH2)2Sn(O2CC(CH3)3)2 (13) achieved 1.4 nm LER at 22 nm half-pitch patterning and a resist composed of (C6H5CH2)2Sn(O2CC6H5)2 (14) achieved 1.1 nm LER at 35 nm half-pitch at high exposure doses (600 mJ/cm2). Two photoresists that use olefin-based carboxylates, (C6H5CH2)2Sn(O2CCH=CH2)2 (11) and (C6H5CH2)2Sn(O2CC(CH3)=CH2)2 (12), demonstrated much improved photospeeds (5 mJ/ cm2 and 27 mJ/cm2) but with worse LER.
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Ryan Del Re, Ryan Del Re, Miriam Sortland, Miriam Sortland, James Pasarelli, James Pasarelli, Brian Cardineau, Brian Cardineau, Yasin Ekinci, Yasin Ekinci, Michaela Vockenhuber, Michaela Vockenhuber, Mark Neisser, Mark Neisser, Daniel Freedman, Daniel Freedman, Robert L. Brainard, Robert L. Brainard, "Low-LER tin carboxylate photoresists using EUV", Proc. SPIE 9422, Extreme Ultraviolet (EUV) Lithography VI, 942221 (19 March 2015); doi: 10.1117/12.2086597; https://doi.org/10.1117/12.2086597

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