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Title: Spin-on-glass coatings for the generation of superpolished substrates for use in the extreme-ultraviolet region

Abstract

Substrates intended for use as extreme-ultraviolet (EUV) optics have extremely stringent requirements in terms of finish. These requirements can dramatically increase the cost and fabrication time, especially when nonconventional shapes, such as toroids, are required. Here we present a spin-on-glass resist process capable of generating superpolished parts from inexpensive substrates. The method has been used to render diamond-turned substrates compatible for use as EUV optics. Toroidal diamond-turned optics with starting rms roughness in the 3.3-3.7 nm range have been smoothed to the 0.4-0.6 nm range. EUV reflectometry characterization of these optics has demonstrated reflectivities of approximately 65%.

Authors:
; ;
Publication Date:
OSTI Identifier:
20779322
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Optics; Journal Volume: 45; Journal Issue: 11; Other Information: DOI: 10.1364/AO.45.002404; (c) 2006 Optical Society of America; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; 36 MATERIALS SCIENCE; COATINGS; DIAMONDS; EXTREME ULTRAVIOLET RADIATION; GLASS; OPTICS; REFLECTIVITY; ROUGHNESS; SUBSTRATES

Citation Formats

Salmassi, Farhad, Naulleau, Patrick P., and Gullikson, Eric M. Spin-on-glass coatings for the generation of superpolished substrates for use in the extreme-ultraviolet region. United States: N. p., 2006. Web. doi:10.1364/AO.45.0.
Salmassi, Farhad, Naulleau, Patrick P., & Gullikson, Eric M. Spin-on-glass coatings for the generation of superpolished substrates for use in the extreme-ultraviolet region. United States. doi:10.1364/AO.45.0.
Salmassi, Farhad, Naulleau, Patrick P., and Gullikson, Eric M. Mon . "Spin-on-glass coatings for the generation of superpolished substrates for use in the extreme-ultraviolet region". United States. doi:10.1364/AO.45.0.
@article{osti_20779322,
title = {Spin-on-glass coatings for the generation of superpolished substrates for use in the extreme-ultraviolet region},
author = {Salmassi, Farhad and Naulleau, Patrick P. and Gullikson, Eric M},
abstractNote = {Substrates intended for use as extreme-ultraviolet (EUV) optics have extremely stringent requirements in terms of finish. These requirements can dramatically increase the cost and fabrication time, especially when nonconventional shapes, such as toroids, are required. Here we present a spin-on-glass resist process capable of generating superpolished parts from inexpensive substrates. The method has been used to render diamond-turned substrates compatible for use as EUV optics. Toroidal diamond-turned optics with starting rms roughness in the 3.3-3.7 nm range have been smoothed to the 0.4-0.6 nm range. EUV reflectometry characterization of these optics has demonstrated reflectivities of approximately 65%.},
doi = {10.1364/AO.45.0},
journal = {Applied Optics},
number = 11,
volume = 45,
place = {United States},
year = {Mon Apr 10 00:00:00 EDT 2006},
month = {Mon Apr 10 00:00:00 EDT 2006}
}
  • Substrates intended for use as extreme ultraviolet (EUV) optics have extremely stringent requirements in terms of finish. These requirements can dramatically increase the cost and fabrication time, especially when non-conventional shapes, such as toroids, are required. Here we present a spin-on-glass resist process capable of generating super-polished parts from inexpensive substrates. The method has been used to render diamond-turned substrates compatible for use as EUV optics. Toroidal diamond-turned optics with starting rms roughness in the 3.3 to 3.7 nm range have been smoothed to the 0.4 to 0.6 nm range. EUV reflectometry characterization of these optics has demonstrated reflectivities ofmore » approximately 63%.« less
  • The fundamental mechanism responsible for optically induced magnetization dynamics in ferromagnetic thin films has been under intense debate since almost two decades. Currently, numerous competing theoretical models are in strong need for a decisive experimental confirmation such as monitoring the triggered changes in the spin-dependent band structure on ultrashort time scales. Our approach explores the possibility of observing femtosecond band structure dynamics by giving access to extended parts of the Brillouin zone in a simultaneously time-, energy- and spin-resolved photoemission experiment. For this purpose, our setup uses a state-of-the-art, highly efficient spin detector and ultrashort, extreme ultraviolet light pulses createdmore » by laser-based high-order harmonic generation. In this paper, we present the setup and first spin-resolved spectra obtained with our experiment within an acquisition time short enough to allow pump-probe studies. Further, we characterize the influence of the excitation with femtosecond extreme ultraviolet pulses by comparing the results with data acquired using a continuous wave light source with similar photon energy. In addition, changes in the spectra induced by vacuum space-charge effects due to both the extreme ultraviolet probe- and near-infrared pump-pulses are studied by analyzing the resulting spectral distortions. The combination of energy resolution and electron count rate achieved in our setup confirms its suitability for spin-resolved studies of the band structure on ultrashort time scales.« less
  • No abstract prepared.
  • No abstract prepared.
  • Condenser optics in extreme ultraviolet lithography (EUVL) systems are subjected to frequent replacement as they are positioned close to the illumination source, where increased heating and contamination occur. In the case of aspherical condenser elements made by optical figuring/finishing, their replacement can be very expensive (several hundred thousand dollars). One approach to this problem would be to manufacture inexpensive illuminator optics that meet all required specifications and could be replaced at no substantial cost. Diamond-turned metal substrates are a factor of 100 less expensive than conventional aspherical substrates but have insufficient finish, leading to unacceptably low EUV reflectance after multilayermore » coating. In this work it is shown that, by applying a smoothing film prior to multilayer coating, the high spatial frequency roughness of a diamond-turned metal substrate is reduced from 1.76 to 0.27 nm rms while the figure slope error is maintained at acceptable levels. Metrology tests performed at various stages of the fabrication of the element demonstrated that it satisfied all critical figure and finish specifications as illuminator. Initial experimental results on the stability and performance of the optic under a real EUVL plasma source environment show no accelerated degradation when compared to conventional substrates.« less