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Title: Study of LOR5B resist for the Fabrication of Hard X-ray Zone Plates by E-beam Lithography and ICP

Abstract

We used an approach combining Inductively Coupled Plasma (ICP) etching process and high resolution electron beam lithography and successfully fabricate high aspect ratio zone plate for hard-x-ray applications. The electron beam lithography defines the pattern with outmost zone dimension smaller than 100nm while the consequently ICP produced high aspect ratio structures. Both chacteristics, high resolution patterning and high aspect ratio are required to produce zone plate devices for multi-keV x-rays. We demonstrated that a zone plate with a 60nm outmost zone and a thickness of 500nm is achievable by this approach.

Authors:
 [1];  [2]; ; ; ;  [1];  [1];  [2];  [3];
  1. Institute of Physics, Academia Sinica, Taipei 115, Taiwan (China)
  2. (China)
  3. Ecole Polytechnique Federale, CH-1015 Lausanne (Switzerland)
Publication Date:
OSTI Identifier:
21049309
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 879; Journal Issue: 1; Conference: 9. international conference on synchrotron radiation instrumentation, Daegu (Korea, Republic of), 28 May - 2 Jun 2006; Other Information: DOI: 10.1063/1.2436353; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; ASPECT RATIO; ELECTRON BEAMS; ETCHING; FABRICATION; HARD X RADIATION; KEV RANGE; MASKING; OPTICS; PLASMA; PLATES; RESOLUTION

Citation Formats

Chen, Y. T., Department of Materials Engineering, Tatung University, Taipei 104, Taiwan, Lin, I. K., Lo, T. N., Liu, C. J., Je, J. H., Su, C. I., Institute of Optoelectronic Science at National Taiwan Ocean University, Keelung 202, Taiwan, Margaritondo, G., and Hwu, Y. Study of LOR5B resist for the Fabrication of Hard X-ray Zone Plates by E-beam Lithography and ICP. United States: N. p., 2007. Web. doi:10.1063/1.2436353.
Chen, Y. T., Department of Materials Engineering, Tatung University, Taipei 104, Taiwan, Lin, I. K., Lo, T. N., Liu, C. J., Je, J. H., Su, C. I., Institute of Optoelectronic Science at National Taiwan Ocean University, Keelung 202, Taiwan, Margaritondo, G., & Hwu, Y. Study of LOR5B resist for the Fabrication of Hard X-ray Zone Plates by E-beam Lithography and ICP. United States. doi:10.1063/1.2436353.
Chen, Y. T., Department of Materials Engineering, Tatung University, Taipei 104, Taiwan, Lin, I. K., Lo, T. N., Liu, C. J., Je, J. H., Su, C. I., Institute of Optoelectronic Science at National Taiwan Ocean University, Keelung 202, Taiwan, Margaritondo, G., and Hwu, Y. Fri . "Study of LOR5B resist for the Fabrication of Hard X-ray Zone Plates by E-beam Lithography and ICP". United States. doi:10.1063/1.2436353.
@article{osti_21049309,
title = {Study of LOR5B resist for the Fabrication of Hard X-ray Zone Plates by E-beam Lithography and ICP},
author = {Chen, Y. T. and Department of Materials Engineering, Tatung University, Taipei 104, Taiwan and Lin, I. K. and Lo, T. N. and Liu, C. J. and Je, J. H. and Su, C. I. and Institute of Optoelectronic Science at National Taiwan Ocean University, Keelung 202, Taiwan and Margaritondo, G. and Hwu, Y},
abstractNote = {We used an approach combining Inductively Coupled Plasma (ICP) etching process and high resolution electron beam lithography and successfully fabricate high aspect ratio zone plate for hard-x-ray applications. The electron beam lithography defines the pattern with outmost zone dimension smaller than 100nm while the consequently ICP produced high aspect ratio structures. Both chacteristics, high resolution patterning and high aspect ratio are required to produce zone plate devices for multi-keV x-rays. We demonstrated that a zone plate with a 60nm outmost zone and a thickness of 500nm is achievable by this approach.},
doi = {10.1063/1.2436353},
journal = {AIP Conference Proceedings},
number = 1,
volume = 879,
place = {United States},
year = {Fri Jan 19 00:00:00 EST 2007},
month = {Fri Jan 19 00:00:00 EST 2007}
}
  • Fresnel phase zone plates for hard x-ray microfocusing have been fabricated. An original x-ray mask written by e-beam lithography was replicated into thick PMMA by x-ray proximity printing. The pattern was transferred into gold and nickel by electroplating. A smallest linewidth of 0.25 [mu]m with an aspect ratio of 14 in the metal pattern has been achieved. Thickness of fabricated zone plates was dictated by a [pi]-phase shift requirement for focusing of the x rays at 8 and 20 keV energies.
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  • Diffractive lenses are becoming the optical elements of choice for many applications. One type of diffractive lens, the binary zone plate, has already demonstrated high-resolution performance experimentally. However, in order to increase the diffraction efficiency of these zone plates, a blazed grating profile must be used. This can best be approximated by a staircase grating profile, created by multilevel exposures. Using x-ray lithograph, we fabricated for the first time circular, linear bi- and trilevel zone plates, with gold structures 0.75 [mu]m thick (per level), on silicon nitride substrates. The zone plates were designed for use at a wavelength of 1.54more » A, and had a theoretical efficiency of 68.5% for bilevel and 81.5% for trilevel zone plates. Due to the large depth of focus and high resolution inherent to x-ray lithography, the finished zone plate exhibits very steep sidewall profiles, with linewidth resolution down to 0.25 [mu]m. Such vertical sidewalls are essential for achieving high lens efficiency. Fabrication errors, such as thickness variation in the electroplated gold and misalignment, were considered, and their effect on the optical efficiency of the zone plate was estimated. Alignment errors between levels were minimized, achieving a best result of 25 nm (3[sigma]). In fabricating the zone plates, we employed standard integrated device tools, such as a Leica Cambridge Electron Beam microfabricator (EBMF) 10cs/120 electron-beam writer for the x-ray mask fabrication, and a Suss 200 x-ray stepper for the multilevel exposures. Thus, we have shown that it will be possible to fabricate many lenses, with a variety of optical characteristics, in one wafer.« less