Idriss Blakey - Synthesis of High Refractive Index Sulfur Containing Polymers for 193nm Immersion Lithography; A Progress Report.

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      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

      DOI: 10.1117/12.659757


      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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