Fabrication of 200 nm period centimeter area hard x-ray absorption gratings by multilayer deposition

S. K. Lynch, C. Liu, N. Y. Morgan, X. Xiao, A. A. Gomella, D. Mazilu, E. E. Bennett, L. Assoufid, F. De Carlo, H. Wen

Research output: Contribution to journalArticle

Abstract

We describe the design and fabrication trials of x-ray absorption gratings of 200nm period and up to 100:1 depth-to-period ratios for full-field hard x-ray imaging applications. Hard x-ray phase-contrast imaging relies on gratings of ultra-small periods and sufficient depth to achieve high sensitivity. Current grating designs utilize lithographic processes to produce periodic vertical structures, where grating periods below 2.0 μm are difficult due to the extreme aspect ratios of the structures. In our design, multiple bilayers of x-ray transparent and opaque materials are deposited on a staircase substrate, and mostly on the floor surfaces of the steps only. When illuminated by an x-ray beam horizontally, the multilayer stack on each step functions as a micro-grating whose grating period is the thickness of a bilayer. The array of micro-gratings over the length of the staircase works as a single grating over a large area when continuity conditions are met. Since the layers can be nanometers thick and many microns wide, this design allows sub-micron grating periods and sufficient grating depth to modulate hard x-rays. We present the details of the fabrication process and diffraction profiles and contact radiography images showing successful intensity modulation of a 25keV x-ray beam.

Original languageEnglish (US)
Article number105007
JournalJournal of Micromechanics and Microengineering
Volume22
Issue number10
DOIs
StatePublished - Oct 1 2012
Externally publishedYes

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Mechanics of Materials
  • Mechanical Engineering
  • Electrical and Electronic Engineering

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    Lynch, S. K., Liu, C., Morgan, N. Y., Xiao, X., Gomella, A. A., Mazilu, D., Bennett, E. E., Assoufid, L., De Carlo, F., & Wen, H. (2012). Fabrication of 200 nm period centimeter area hard x-ray absorption gratings by multilayer deposition. Journal of Micromechanics and Microengineering, 22(10), [105007]. https://doi.org/10.1088/0960-1317/22/10/105007