Effect of photoacid generator additives on the dissolution behavior of bis-trifluoromethyl carbinol substituted polynorbornene

Alicyclic polymers, such as substituted polynorbornenes, are one potential material solution for providing photoresist polymer resins with high transparency backbones for photolithography at 193 nm and 157 nm wavelengths. In addition, the bis-trifluoromethyl carbinol functional group has been identified as a highly transparent base soluble group that can be used for producing photoresist resins from polynorbornene materials for 157 nm lithography. In this work, the interactions between commercial photoacid generators (PAGs) and bis-trifluoromethyl carbinol substituted polynorbornene (HFAPNB) are examined. It was found that photoacid generators can act as strong dissolution inhibitors for bis-trifluoromethyl carbinol substituted polynorbornene homopolymers. More importantly, it was found that a variety of photoacid generators can act as photoswitchable dissolution inhibitors for these materials, with exposure of the photoacid generator resulting in a reduction in the dissolution inhibition (i.e. increased dissolution rate) of the functionalized polynorbornene. The complete inhibition of unexposed HFAPNB polymers by iodonium photoacid generators allows for the formulation of photodefinable materials using a simple two component system consisting only of PAG and the HFAPNB polymer.