Use of highly EUV absorbing element in chemically amplified resist

We propose a method for easily determining the extent of solubility change of chemically amplified resist (CAR) films with different types of extreme UV (EUV)-absorbing elements. The concentration of acid molecules depends on the production yield of secondary electrons, and it affects the deprotection reaction rate in the resist and ultimately the residual resist film thickness. Materials capable of increasing EUV absorption were prepared by incorporating tin, iodine, or hydrogen in a model fluoroalkylated copolymer. A CAR film containing a proton exchange component was spin-coated on a substrate, and a thin film composed of one of the fluoroalkylated copolymers containing elements and a photoacid generator was cast thereon. Under EUV irradiation, the iodine containing copolymer increased the decomposition rate of the CAR film, unlike the case of the tin- or hydrogen containing copolymer. For practical use, we prepared an iodinated sensitizer based on a CT contrast agent, iohexol, for utilizing it as an EUV sensitizer in an EUV lithography (EUVL) experiment, and it was found that the iohexol-based iodinated sensitizer could simultaneously act as a sensitizer and a base quencher. These results show that iodinated compounds can help enhance the patterning performance of CARs in EUVL.