No abstract

We propose a simple additive approach to simulate X-ray photoelectron spectra (XPS) of macromolecules based on the GW method. Single-shot GW (G 0 W 0 ) is a promising technique to compute accurate core-electron binding energies (BEs). However, its application to large molecules is still unfeasible. To circumvent the computational cost of G 0 W 0 , we break the macromolecule into tractable building blocks, such as isolated monomers, and sum up the theoretical spectra of each component, weighted by their molar ratio. In this work, we provide a first proof of concept by applying the method to four test polymers and one copolymer, and show that it leads to an excellent agreement with experiments. The method could be used to retrieve the composition of unknown materials and study chemical reactions, by comparing the simulated spectra with experimental ones.

Science stands on three legs: hypothesis, experiment, and simulation. This holds true for researching extreme ultraviolet (EUV) exposure of photoresist. Hypothesis: For resist exposure as patterns get smaller and closer together, approaching molecular units in width and resist-height, the molecular dynamics will limit the working resolution of the resist due to the formation of printing defects. Without taking proper consideration of these dynamics, the single-patterning lithography roadmap may end prematurely. Experimentally we are developing methods for sub-picosecond tracking of photoionization-induced processes. Using ultrashort pulses of light to excite and probe new materials with techniques that show the interactive dynamics of electronic and nuclear motion at the very limits of light-speed. This certainly holds true for exposing photoresists with EUV where ultrafast photoreactions induce chemical change via multiple pathways such as high-energy ionization fragmentation, recombination, and multispecies combination that ideally end in low-energy electron transfer reactions, analogous to lower energy photoreaction (but with a charge). In the nonideal case, these reaction processes lead to incompatible byproducts of the radiolysis that lead to types of stochastic defects. To do ultrafast studies we must build a foundation of knowledge using atomistic simulation to interpret transient molecular dynamic processes. Before we can do this, we need to learn how to simulate various spectral modalities to provide a starting point. In this work, we examine X-ray Photoelectron Spectroscopy of a model resist and use atomistic simulation to interpret the reactant-product composition of the spectral samples.