Publication Details (including relevant citation information):
Blakey, I.; Conley, W.; George, G. A.; Hill, D. J. T.; Liu, H.; Rasoul, F.; Whittaker, A. K., Proc. SPIE 2006, 6153, 61530H/1-61530H/10
To be able to extend the 193 nm immersion lithography technology platform, the development of high refractive index immersion fluids and resists is required. This paper reports our investigations into generating high refractive index polymers for use in photoresist formulations for 193 nm immersion lithograph. In this study a series of model compounds have been screened for refractive index and transparency at 589 nm and 193 nm. For the compounds studied this series of experiments demonstrated that sulfur-containing compounds have a positive effect on the refractive index of a molecule at 589 nm. However, the situation is complicated by the presence of absorption bands for some small molecules in the low waveleingth region. To demonstrate this, we examined the refractive index dispersion of a series of molecules based on ethyl acetate with varying degrees of sulfur substitution. These results indicated that an anomalous increase in refractive index could be expected 20 - 30 nm above the absorption maximum. The implications for design of high refractive index resists for 193 nm immersion lithography are discussed.
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