Experimental characterization of model extreme ultraviolet resist materials

Resists are needed to advance extreme ultraviolet (EUV) lithography. In EUV resists, due to the high energy of the incident photons, most of the chemistry arises from the emitted primary and secondary electrons and not the EUV photons themselves. 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. In this work, we present several experimental techniques to probe model polymer materials to investigate the impact of specific chemical groups on critical resist properties: EUV absorption, electron emission, electron attenuation length (EAL), and energy distribution of emitted electrons. Total electron yield provides information on the conversion of absorbed EUV photons to electrons, and photoelectron spectroscopy provides information on energy distribution of generated electrons. The EAL reveals the distance that the electrons can travel in a resist film, which is related to the electron blur. Correlations between the obtained experimental values are discussed. We explore how different elements or functional groups change the yield, EAL, and energy distribution of emitted electrons, aiming to understand how to control the electron cascade.