Mixed-ligand zinc-oxoclusters: efficient chemistry for high resolution nanolithography

Extreme ultraviolet lithography (EUVL) is the current technology used in the semiconductor industryfor the fabrication of integrated circuits (ICs), since it enables the further miniaturization of theircomponents. For its optimal operation, photoresist materials that can efficiently use EUV photons(92 eV) to yield sub-10 nm patterns are required. However, there is a lack of understanding of thecomplex mechanisms induced by EUV radiation. In this work, we investigate the ability of a newZn-based oxocluster to fulfil the state-of-the-art requirements for EUVL. This molecular material wasconceived to provide high EUV absorptivity, owing to its contents of Zn, F, and O atoms, and highresolution, given its small molecular size. High sensitivity/reactivity towards EUV is achieved through itsmixed-ligand organic shell composed of methacrylate and trifluoroacetate ligands. This new resistshows outstanding lithography performance yielding down to 22 nm half pitch line/space patterns atB20 mJ cm2. Spectroscopy studies on EUV exposed samples revealed an unexpected reactionpathway where fluoride ions are formed. This is an unprecedented way of efficiently inducing a solubilityswitch in an inorganic resist upon EUV irradiation.

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