Novel high-index resists for 193-nm immersion lithography and beyond

Abstract

A preliminary Quantitative Structure Property Relationship (QSPR) model for predicting the refractive index of small molecules and polymers at 193 nm is presented. Although at this stage the model is only semiquantitative we have found it useful for screening databases of commercially-available compounds for high refractive index targets to include in our program of synthesis of high refractive index resist polymers. These resists are targeted for use in 2nd and 3rd generation 193 nm immersion lithography. Using this methodology a range of targets were identified and synthesized via free radical polymerization. Novel resist polymers were also synthesized via Michael addition polymerization. Preliminary dose to clear experiments identified a number of promising candidates for incorporation into high refractive index resist materials. Furthermore, we have demonstrated imaging of a high index resist using water-based 193 nm immersion lithography.