Synthesis and Electron-Induced Reactions of First Row Transition Metal Complexes as EUV Resist Candidates

Johnathon Johnson, Patrick Eckhert, Rhea-Shree Patel, Howard Fairbrother, Lisa McElwee-White

University of Florida, Johns Hopkins University

EUVL is the next generation lithographic technique for the fabrication of integrated circuits. In EUVL a 13.5nm light is focused onto a photoresist to induce chemical reactions that change the solubility of the photoresist. The photoresist is then selectively developed with a solvent to create a photopattern; the creation of which is the first and limiting step in the miniaturization of a device’s feature. Chemically amplified resists (CARs) consisting of a polymer, a photoacid generator, and a dissolution inhibitor, have been the preferred photoresist used in photolithography for decades. CARs work by a mechanism of acid-catalyzed polymer decomposition upon electron beam irradiation that cause the polymer to become more soluble. However, due to uncontrolled acid diffusion and lower etch resistance, CARs are falling out of favor as the preferred photoresists. Recently, inorganic photoresists have been investigated as the transition metals have higher etch resistance and are typically high absorbers of EUV light. Despite this, metal oxide nanoparticles currently used in EUVL are currently held back in their performance due to their high content of low absorbing elements such as carbon and oxygen. To optimize the use of light in EUVL, new photoresists containing a high content of efficient absorbers of EUV such as iodine, nickel and zinc must be developed. In this study we report the electron beam patterning and reactions of highly absorbing complexes with a M(μ-I)₂I₂L₂ dimer core that maximizes the content of the highly absorbing elements in the structure. The mechanisms of the electron beam induced chemistry will be probed with X-ray photoelectron spectroscopy, quadrupole mass spectrometry, and infrared spectroscopy.