Metal oxo clusters: molecular design for extreme ultraviolet lithography
With the downsizing of transistors, computer chips become smaller and more efficient. Photolithography is the photochemical technique by which patterns are transferred onto silicon wafers, allowing the building up of transistors layer-by-layer. To achieve smaller sizes, shorter and shorter wavelengths of light are being employed, the latest development being so-called extreme ultraviolet (EUV) lithography that uses 13.5 nm. Photoresists are the light-sensitive materials that are crucial in photolithography for transferring patterns. Photoresists containing metallic elements and organic functional groups emerge as the most promising materials for EUV lithography, but the EUV-induced chemistry in these materials is not yet well understood, which hinders the design of photoresists with optimal performance for EUV lithography. This thesis aims to understand the influence of the molecular composition of metal oxo clusters (MOCs) on the chemical changes and the lithographic performance of the materials upon EUV radiation, with a focus on the role of organic ligands.