A novel stable zinc-oxo cluster for advanced lithography patterning

Abstract

Recently, the development of novel metal-containing resists has received much attention in extreme ultraviolet lithography (EUVL) owing to their smaller sizes and higher EUV absorptivity than traditional polymer resists. Herein, we report zinc (Zn)-VBA, a novel stable zinc-oxo cluster-based photoresist molecule with the [Zn4O]6+ inner core and six organic ligands based on 4-vinylbenzoic acid. Zn-VBA was simply prepared by the reactions between the zinc-oxide and 4-vinylbenzoic acid, exhibiting atomically precise structure and good batch stability. Based on single-crystal X-ray diffraction analysis, the size of Zn-VBA is 2.2 nm, which is in line with the high-resolution requirements for advanced lithography technology. Zn-VBA exhibits excellent thermal stability up to 400 °C, much better than the reported zinc-based clusters. Moreover, theoretical studies have revealed the roles of organic ligands in their high thermal stability. Spin-coating methods were employed to fabricate homogenous thin films of Zn-VBA, which showed a quite small roughness value in the absence of viscosifiers, as confirmed by atomic force microscopy images. More importantly, the Zn-VBA films performed well in the electron beam lithography (EBL) and EUVL tests without the addition of photoinitiators, giving prominent pattern lines. This work proves the structural advantages of benzoic-acid-based zinc-oxo clusters as promising EUV patterning materials, which inspire future exploration of metal-oxo clusters (MOCs) resist materials for advanced lithography.