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Proceedings Paper

Photochemical conversion of tin-oxo cage compounds studied using hard x-ray photoelectron spectroscopy
Author(s): Yu Zhang; Jarich Haitjema; Xiaomeng Liu; Fredrik Johansson; Andreas Lindblad; Sonia Castellanos; Niklas Ottosson; Albert M. Brouwer
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Paper Abstract

Several metal-containing molecular inorganic materials are currently considered as photoresists for extreme ultraviolet lithography (EUVL). This is primarily due to their high EUV absorption cross section and small building block size, properties which potentially allow both 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. As a step in this direction, we here 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 [(SnR)12O14(OH)6]X2 (R = organic group; X = anion) which is spin coated to thin layers of 20 nm. The core electronic structure (Sn 3d, O 1s and C 1s) of fresh and DUV exposed films were then investigated using synchrotron radiationbased hard X-ray photoelectron spectroscopy (HAXPES). This method provides information about the structure and chemical state of the respective atoms in the material. We performed a comparative HAXPES study of the composition of the tin-oxo cage compound [(SnR)12O14(OH)6](OH)2, either fresh directly after spin-coated vs. DUV-exposed materials under either ambient condition or under a dry N2 atmosphere. Different chemical oxidation states and concentrations of atoms and atom types in the fresh and exposed films were found. We further found that the chemistry resulting from exposure in air and N2 is strikingly different, clearly illustrating the influence of film-gas interactions on the (photo)chemical processes that eventually determine the photoresist. Finally, a mechanistic hypothesis for the basic DUV photoreactions in molecular tin-oxo cages is proposed.

Paper Details

Date Published: 27 March 2017
PDF: 10 pages
Proc. SPIE 10146, Advances in Patterning Materials and Processes XXXIV, 1014606 (27 March 2017); doi: 10.1117/12.2257893
Show Author Affiliations
Yu Zhang, Advanced Research Ctr. for Nanolithography (Netherlands)
Jarich Haitjema, Advanced Research Ctr. for Nanolithography (Netherlands)
Xiaomeng Liu, Advanced Research Ctr. for Nanolithography (Netherlands)
Fredrik Johansson, Uppsala Univ. (Sweden)
Andreas Lindblad, Uppsala Univ. (Sweden)
Sonia Castellanos, Advanced Research Ctr. for Nanolithography (Netherlands)
Niklas Ottosson, Advanced Research Ctr. for Nanolithography (Netherlands)
AMOLF (Netherlands)
Albert M. Brouwer, Advanced Research Ctr. for Nanolithography (Netherlands)
Univ. van Amsterdam (Netherlands)

Published in SPIE Proceedings Vol. 10146:
Advances in Patterning Materials and Processes XXXIV
Christoph K. Hohle, Editor(s)

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