25 March 2016 Studying electron-PAG interactions using electron-induced fluorescence
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Abstract
In extreme ultraviolet (EUV) lithography, 92 eV photons are used to expose photoresists. Typical EUV resists are organic-based and chemically amplified using photoacid generators (PAGs). Upon exposure, PAGs produce acids which catalyze reactions that result in changes in solubility. In EUV lithography, photo- and secondary electrons (energies of 10- 80 eV) play a large role in PAG acid-production. Several mechanisms for electron-PAG interactions (e.g. electron trapping, and hole-initiated chemistry) have been proposed. The aim of this study is to explore another mechanism – internal excitation – in which a bound PAG electron can be excited by receiving energy from another energetic electron, causing a reaction that produces acid. This paper explores the mechanism of internal excitation through the analogous process of electron-induced fluorescence, in which an electron loses energy by transferring that energy to a molecule and that molecule emits a photon rather than decomposing. We will show and quantify electron-induced fluorescence of several fluorophores in polymer films to mimic resist materials, and use this information to refine our proposed mechanism. Relationships between the molecular structure of fluorophores and fluorescent quantum yield may aid in the development of novel PAGs for EUV lithography.
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Amrit Narasimhan, Amrit Narasimhan, Steven Grzeskowiak, Steven Grzeskowiak, Jonathan Ostrander, Jonathan Ostrander, Jonathon Schad, Jonathon Schad, Eliran Rebeyev, Eliran Rebeyev, Mark Neisser, Mark Neisser, Leonidas E. Ocola, Leonidas E. Ocola, Gregory Denbeaux, Gregory Denbeaux, Robert L. Brainard, Robert L. Brainard, "Studying electron-PAG interactions using electron-induced fluorescence", Proc. SPIE 9779, Advances in Patterning Materials and Processes XXXIII, 97790F (25 March 2016); doi: 10.1117/12.2219850; https://doi.org/10.1117/12.2219850
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