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

Abstract

Extreme ultraviolet lithography (EUVL) is the current technology used in the semiconductor industry for the fabrication of integrated circuits (ICs), since it enables the further miniaturization of their components. 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 the complex mechanisms induced by EUV radiation. In this work, we investigate the ability of a new Zn-based oxocluster to fulfil the state-of-the-art requirements for EUVL. This molecular material was conceived to provide high EUV absorptivity, owing to its contents of Zn, F, and O atoms, and high resolution, given its small molecular size. High sensitivity/reactivity towards EUV is achieved through its mixed-ligand organic shell composed of methacrylate and trifluoroacetate ligands. This new resist shows outstanding lithography performance yielding down to 22 nm half pitch line/space patterns at ∼20 mJ cm⁻². Spectroscopy studies on EUV exposed samples revealed an unexpected reaction pathway where fluoride ions are formed. This is an unprecedented way of efficiently inducing a solubility switch in an inorganic resist upon EUV irradiation.