Patterning of aligned structures on supporting thin membranes is required in many applications, such as fabrication of stacked zone plates and realization of observation windows in nanofluidic channels. Here, the authors present a process flow to fabricate self-aligned structures on both sides of a membrane stack by means of a single-step through-membrane 100-keV electron beam exposure. High energy of the electron beam ensures that the electrons are able to propagate through the membrane stack that is coated with resist on both sides, while the single-step exposure ensures that subsequently etched structures in the supporting silicon nitride membranes are perfectly aligned. Simulations of electron scattering indicate that for micrometer-sized structures the exposed region (containing 90% of the deposited dose) broadening is ∼220 nm for a thick ∼6-μm membrane stack (500 nm of SiO2 sandwiched between two 250 nm-thick SiNx layers, with the membrane stack coated with 1 μm of PMMA resist on each side). This corresponds well with the broadening measured from the imaged cross sections of structures etched into the top and bottom SiNx encapsulating membranes. The broadening can be further optimized by adjusting the process parameters and reducing the thicknesses of the membranes and of the PMMA resist. The relatively small feature-broadening at the bottom of the membrane stack indicates that perfectly aligned submicrometer features are feasible.
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September 2019
Research Article|
August 14 2019
Self-aligned structures by a single-step through-membrane 100-keV electron beam lithography
Sergey Gorelick
;
Sergey Gorelick
a)
1
Department of Biochemistry and Molecular Biology, Faculty of Medicine, Nursing and Health Sciences
, 23 Innovation Walk, 3800 Clayton, Victoria, Australia
2
ARC Centre of Excellence in Advanced Molecular Imaging, Monash University
, Clayton, Victoria 3800, Australia
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Alex de Marco
Alex de Marco
1
Department of Biochemistry and Molecular Biology, Faculty of Medicine, Nursing and Health Sciences
, 23 Innovation Walk, 3800 Clayton, Victoria, Australia
2
ARC Centre of Excellence in Advanced Molecular Imaging, Monash University
, Clayton, Victoria 3800, Australia
3
University of Warwick
, Coventry CV4 7AL, United Kingdom
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a)
Electronic mail: sergey.gorelick@monash.edu
Note: This paper is part of the Conference Collection: The 63rd International Conference on Electron, Ion, and Photon Beam Technology and Nanofabrication (EIPBN 2019).
J. Vac. Sci. Technol. B 37, 051602 (2019)
Article history
Received:
June 12 2019
Accepted:
July 29 2019
Citation
Sergey Gorelick, Alex de Marco; Self-aligned structures by a single-step through-membrane 100-keV electron beam lithography. J. Vac. Sci. Technol. B 1 September 2019; 37 (5): 051602. https://doi.org/10.1116/1.5114948
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