Photochemical conversion of tin-oxo cage compounds studied using hard x-ray photoelectron spectroscopy

Yu Zhang; Jarich Haitjema; Xiaomeng Liu; Fredrik Johansson; Andreas Lindblad; Sonia Castellanos; Niklas Ottosson; Albert M. Brouwer

doi:10.1117/1.JMM.16.2.023510

22 June 2017 Photochemical conversion of tin-oxo cage compounds studied using hard x-ray photoelectron spectroscopy

Yu Zhang, Jarich Haitjema, Xiaomeng Liu, Fredrik Johansson, Andreas Lindblad, Sonia Castellanos, Niklas Ottosson, Albert M. Brouwer

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Journal of Micro/Nanolithography, MEMS, and MOEMS, Vol. 16, Issue 2, 023510 (June 2017). https://doi.org/10.1117/1.JMM.16.2.023510

Abstract

Molecular inorganic materials are currently considered photoresists for extreme ultraviolet lithography (EUVL). Their high EUV absorption cross section and small building block size potentially allow high sensitivity and resolution as well as low line-edge roughness. The photochemical reaction mechanisms that allow these kinds of materials to function as photoresists, however, are still poorly understood. We discuss photochemical reactions upon deep UV (DUV) irradiation of a model negative-tone EUV photoresist material, namely the well-defined molecular tin-oxo cage compound [(SnBu)12O14(OH)6](OH)2, which is spin-coated to thin layers of 20 nm. The core electronic structures (Sn 3d, O 1s, and C 1s) of unexposed and DUV exposed films were then investigated using synchrotron radiation-based hard x-ray photoelectron spectroscopy. Different chemical oxidation states and concentrations of atoms and atom types in the unexposed and exposed films were found. We observed that the exposure in a nitrogen atmosphere prevented the oxidation but still led to carbon loss, albeit with a smaller conversion. Finally, a mechanistic hypothesis for the basic DUV photoreactions in molecular tin-oxo cages is proposed.

CC BY: © The Authors. Published by SPIE under a Creative Commons Attribution 4.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

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Yu Zhang, Jarich Haitjema, Xiaomeng Liu, Fredrik Johansson, Andreas Lindblad, Sonia Castellanos, Niklas Ottosson, and Albert M. Brouwer "Photochemical conversion of tin-oxo cage compounds studied using hard x-ray photoelectron spectroscopy," Journal of Micro/Nanolithography, MEMS, and MOEMS 16(2), 023510 (22 June 2017). https://doi.org/10.1117/1.JMM.16.2.023510

Received: 10 April 2017; Accepted: 2 June 2017; Published: 22 June 2017

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