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Microsystem Technologies

, Volume 20, Issue 10–11, pp 2045–2050 | Cite as

X-ray zone plates with 25 aspect ratio using a 2-μm-thick ultrananocrystalline diamond mold

  • Michael J. WojcikEmail author
  • Derrick C. Mancini
  • Ralu Divan
  • Leonidas E. Ocola
Technical Paper

Abstract

Hard X-ray phase zone plates are focusing optics used for X-ray microscopes at synchrotron radiation facilities. The resolution is determined by the outer-most zone width (OZW) and modern lithographic techniques are capable of patterning OZW less than 100 nm. Efficiency of a phase zone plate will peak when the zones have a thickness that provides a π-phase shift to the X-rays. Thus, a hard X-ray zone plate with ideal efficiency and sub-100-nm resolution requires fabricating high-aspect-ratio, dense-packed structures in materials suitable for exposure to synchrotron radiation. The fabrication method implemented involves an electroforming mold process where a top resist layer is lithographically patterned and used for pattern transfer into a bottom layer which acts as the electroform mold. The resulting mold is filled with Au by electroplating, and afterwards the mold is not removed but remains in place for mechanical support. Ultrananocrystalline diamond (UNCD) was used as the mold layer. UNCD is deposited by hot-filament chemical vapor deposition with well-controlled stress and thickness up to 2 μm. The top resist layer is hydrogen silsesquioxane, which is a high-contrast electron beam lithography resist and resistant to the oxygen reactive ion etching required for UNCD pattern transfer. Using this fabrication method, we successfully produced zone plates with OZW down to 80 nm and an aspect ratio up to 25 for a thickness of 2 μm. The efficiency of several fabricated zone plates were measured, demonstrating their functionality.

Keywords

Outer Zone Zone Plate Mold Material Pattern Transfer Electron Storage Ring 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Notes

Acknowledgments

We acknowledge Daniel Rosenmann and Ross Harder for their assistance, Advanced Diamond Technologies for supplying UNCD films. Use of the Center for Nanoscale Materials and the Advanced Photon Source was supported by the U. S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.

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Copyright information

© Springer-Verlag Berlin Heidelberg (outside the USA)  2014

Authors and Affiliations

  • Michael J. Wojcik
    • 1
    Email author
  • Derrick C. Mancini
    • 1
  • Ralu Divan
    • 1
  • Leonidas E. Ocola
    • 1
  1. 1.Argonne National LaboratoryArgonneUSA

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