The role of the organic shell in hybrid molecular materials for EUV lithography

As EUV lithography is being introduced into the market, the need for resists that can satisfy the exigent requirements of sensitivity, resolution, and line-edge roughness requires the development of guidelines for new generations of materials. In this work, we aim for gaining more understanding on the contribution of the organic components in inorganic-organic hybrid molecular resists to their sensitivity. A method to investigate the effect of specific functionalities on the sensitivity of metal oxo clusters is presented, which consists in the "doping" of the methacrylate shell through the introduction of fluorinated, iodinated and extended aromatic ligands. By introducing each of these functionalities in small ratios to the methacrylate ligand (1:11 and 2:10) the main chemical properties of the materials (solubility and molecular packing in the thin film) are expected to be unaltered. Our investigations show that the sensitivity is enhanced in the presence of halogens and drastically decreased when extended aromatic compounds are introduced. The trends are uncorrelated with the absorptivity estimated for each material, which seems to indicate that the doping functionalities might interfere with the cross-linking of the methacrylate ligands or introduce new chemical pathways. Our results indicate that specific organic functionalities can be used to tune the reactivity of hybrid compounds for EUV light by introducing them in doping amounts, thus preserving the processability of the initial material.