New photoresists are needed to advance Extreme Ultraviolet (EUV) lithography. Tailored design of efficient resists is impossible without a fundamental understanding of EUV induced chemistry. In EUV resists, due to the high energy of the incident photons, most of the chemistry arises from the emitted electrons and not the EUV photons themselves. The absorption of an EUV photon by a resist film leads to the emission of primary electrons, which, through a cascade of inelastic scattering events, cause excitation of molecules and subsequent emission of secondary electrons. The electrons may travel up to tens of nanometers before losing their kinetic energy via collisions which initiate chemical reactions. Because the electrons are playing a leading role in EUV patterning, initiating chemical transformations, it is important to characterize their generation, transport, and energy distribution. Previously, we demonstrated a suite of experimental techniques capable of characterizing EUV absorption, electron yield, and electron attenuation length of resist materials. In this work we demonstrate how to experimentally investigate the energy spectrum of those electrons via EUV photoelectron spectroscopy of thin films. We explore how different elements or functional groups may change the energy distribution of emitted electrons, aiming to understand how to control the electron cascade.
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