A novel stable zinc-oxo cluster for advanced lithography patterning

• Published in: Journal of materials chemistry. A, Materials for energy and sustainability Materials for energy and sustainability, 2023-02, Vol.11 (9), p.481-487
• Main Authors: Si, Youming, Zhao, Yingdong, Shi, Guangyue, Zhou, Danhong, Luo, Feng, Chen, Pengzhong, Fan, Jiangli, Peng, Xiaojun
• Format: Article
• Language: English
• Subjects: Absorptivity; Atomic force microscopy; Clusters; Electron beam lithography; Ligands; Lithography; Pattern formation; Patterning; Photoinitiators; Photoresists; Polymers; Resists; Single crystals; Spin coating; Stability analysis; Thermal stability; Thin films; X-ray diffraction; Zinc
• ISSN: 2050-7488; 2050-7496
• DOI: 10.1039/d3ta00115f

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 [Zn 4 O] 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. Single crystal X-ray diffraction analysis showed a Zn- VBA with a size of 2.2 nm, in line with advanced lithography technology requirements. The introduction of benzoic acid ligands resulted in high thermal stability, good solubility, and good film-forming capability.