Time-Dependent Density Functional Theory Calculations of Photoabsorption of Fluorinated Cyclic Molecules in the Vacuum Ultraviolet Region

Abstract

Time-dependent density functional theory (TD-DFT) calculations of the photoabsorption of molecules in the vacuum ultraviolet region have been performed in order to aid in the design of transparent materials for use as photoresists for F 2 lithography (157 nm). The method including an empirical equation for correcting the calculated transition energy is described. We have used the TD-DFT approach to predict the photoabsorption of substituted benzenes, and cycloalkanes including norbornane. The calculations show that norbornane is the best cycloalkane on which to start substitution studies. We report results on the mono-, di-, and tetra-fluorinated derivatives. The results show that the tetrafluoro-norbornanes have the lowest absorption in the 157 nm range for the molecules that we studied.