Polymers with well-controlled molecular weight for DUV/VUV lithography

Polymer resin is a major component of a photoresist formulation. Therefore, the performance of a photoresist strongly depends on the composition and properties of the resin in the formulation. We have developed a polymerization method, which is able to control the molecular weights along with the compositions of copolymers over a wide range of monomer for the end use in 193 nm or 157 nm photoresist applications. The method is called controlled radical polymerization (CRP). In use of this method, we successfully prepared an acrylate-type copolymer with low molecular weight distribution (PDI similar to 1.2). Furthermore, the desired molecular weight of the polymers can be obtained easily altered by mild reaction condition change. Large-scale production has been demonstrated feasible. In the extension of the application of CRP, we also carried out the homopolymerization reaction of fluorinated norbornene-tpye monomers, and copolymerization of norbornene-type monomers with acrylates to be used in 157 nm photoresists. The results in this study show that this method can improve the molecular weight control on polymer synthesis. Measurement of the aborbance of some monomers and polymers on synchrotron radiation spectrometers will be presented here. Absorbances of our monomers are between 1456 and 5175 (L/mol cm). However, absorbances of our polymers show different data between SR andVASE measurement methods.