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Title: The importance of inner-shell electronic structure for enhancing the EUV absorption of photoresist materials

Abstract

In order to increase computation power and efficiency, the semiconductor industry continually strives to reduce the size of features written using lithographic techniques. The planned switch to a shorter wavelength extreme ultraviolet (EUV) source presents a challenge for the associated photoresists, which in their current manifestation show much poorer photoabsorption cross sections for the same dose. Here we consider the critical role that an inner-shell electronic structure might play in enhancing photoabsorption cross sections, which one can control by the choice of substituent elements in the photoresist. In order to increase the EUV sensitivity of current photoresists, it is critical to consider the inner-shell atomic structure of the elements that compose the materials. We validate this hypothesis using a series of halogenated organic molecules, which all have similar valence structures, but differ in the character of their semi-core and deep valence levels. Using various implementations of time-dependent density functional theory, the absorption cross sections are computed for the model systems of CH3X, X = H, OH, F, Cl, Br, I, as well as a representative polymer fragment: 2-methyl-phenol and its halogenated analogues. Iodine has a particularly high cross section in the EUV range, which is due to delayed absorption bymore » its 4d electrons. The computational results are compared to standard database values and experimental data when available. Generally we find that the states that dominate the EUV oscillator strength are generated by excitations of deep valence or semi-core electrons, which are primarily atomic-like and relatively insensitive to the specific molecular structure.« less

Authors:
 [1];  [1];  [1];  [1]
  1. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Publication Date:
Research Org.:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Materials Sciences & Engineering Division; USDOE
OSTI Identifier:
1476485
Alternate Identifier(s):
OSTI ID: 1361838
Grant/Contract Number:  
AC02-05CH11231
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Journal of Chemical Physics
Additional Journal Information:
Journal Volume: 146; Journal Issue: 16; Journal ID: ISSN 0021-9606
Publisher:
American Institute of Physics (AIP)
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS

Citation Formats

Closser, Kristina D., Ogletree, D. Frank, Naulleau, Patrick, and Prendergast, David. The importance of inner-shell electronic structure for enhancing the EUV absorption of photoresist materials. United States: N. p., 2017. Web. doi:10.1063/1.4981815.
Closser, Kristina D., Ogletree, D. Frank, Naulleau, Patrick, & Prendergast, David. The importance of inner-shell electronic structure for enhancing the EUV absorption of photoresist materials. United States. doi:10.1063/1.4981815.
Closser, Kristina D., Ogletree, D. Frank, Naulleau, Patrick, and Prendergast, David. Thu . "The importance of inner-shell electronic structure for enhancing the EUV absorption of photoresist materials". United States. doi:10.1063/1.4981815. https://www.osti.gov/servlets/purl/1476485.
@article{osti_1476485,
title = {The importance of inner-shell electronic structure for enhancing the EUV absorption of photoresist materials},
author = {Closser, Kristina D. and Ogletree, D. Frank and Naulleau, Patrick and Prendergast, David},
abstractNote = {In order to increase computation power and efficiency, the semiconductor industry continually strives to reduce the size of features written using lithographic techniques. The planned switch to a shorter wavelength extreme ultraviolet (EUV) source presents a challenge for the associated photoresists, which in their current manifestation show much poorer photoabsorption cross sections for the same dose. Here we consider the critical role that an inner-shell electronic structure might play in enhancing photoabsorption cross sections, which one can control by the choice of substituent elements in the photoresist. In order to increase the EUV sensitivity of current photoresists, it is critical to consider the inner-shell atomic structure of the elements that compose the materials. We validate this hypothesis using a series of halogenated organic molecules, which all have similar valence structures, but differ in the character of their semi-core and deep valence levels. Using various implementations of time-dependent density functional theory, the absorption cross sections are computed for the model systems of CH3X, X = H, OH, F, Cl, Br, I, as well as a representative polymer fragment: 2-methyl-phenol and its halogenated analogues. Iodine has a particularly high cross section in the EUV range, which is due to delayed absorption by its 4d electrons. The computational results are compared to standard database values and experimental data when available. Generally we find that the states that dominate the EUV oscillator strength are generated by excitations of deep valence or semi-core electrons, which are primarily atomic-like and relatively insensitive to the specific molecular structure.},
doi = {10.1063/1.4981815},
journal = {Journal of Chemical Physics},
number = 16,
volume = 146,
place = {United States},
year = {Thu Apr 27 00:00:00 EDT 2017},
month = {Thu Apr 27 00:00:00 EDT 2017}
}

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Works referenced in this record:

X-Ray Interactions: Photoabsorption, Scattering, Transmission, and Reflection at E = 50-30,000 eV, Z = 1-92
journal, July 1993

  • Henke, B. L.; Gullikson, E. M.; Davis, J. C.
  • Atomic Data and Nuclear Data Tables, Vol. 54, Issue 2, p. 181-342
  • DOI: 10.1006/adnd.1993.1013