Tech Briefs Magazine - February 2021 - 40

Manufacturing &
Prototyping

Wafer-Scale Membrane Release Process
This process fabricates thin dielectric membranes with high mechanical yields.
Goddard Space Flight Center, Greenbelt, Maryland

recise measurements utilizing sensitive instruments may require thermally managed detectors; therefore,
thermal insulation of the detector is
essential to its performance. To maintain critical signal-to-noise ratio, there is
a need for larger thermal isolation
structures. Due to high detector filling
fraction limits, these isolation structures
may be thinner, less mechanically robust, and more prone to breakage during fabrication.
This innovation is a process that fabricates thin dielectric membranes with
high mechanical yields. These dielectric

membranes may be perforated and include thermal isolation structures.
The process of forming a thermal insulation wafer begins with layering a photoresist pattern on an aluminum coated
substrate. After the aluminum is etched, a
temporary adhesive is applied to the photoresist and substrate. Next, the construction undergoes wafer scale bonding to a
silicon insulator. The silicon insulator is
then patterned and etched down to the
buried oxide layer. The temporary adhesive is then dissolved in acetone. The acetone is diluted with non-polar solvents
that are then removed via critical drying.

Multiple arrays of crystalline silicon
membranes were produced that were 450nm thick and were isolated from a silicon
support structure by thermal isolation
structures that were 30 microns thick and
5 microns long. The largest membranes,
which had 100% mechanical yield, had an
aerial footprint of 1.6 × 1.4 mm.
NASA is actively seeking licensees to commercialize this technology. Please contact
NASA's Licensing Concierge at Agency-PatentLicensing@mail.nasa.gov or call us at 202-3587432 to initiate licensing discussions. Follow
this link for more information: https://
technology.nasa.gov/patent/GSC-TOPS-231.

Manufacturing Ultra-Thin Camera Lenses
Ultra-thin and flexible metalenses could replace traditional camera lenses.
Chalmers University of Technology, Gothenburg, Sweden

n the future, camera lenses could be
thousands of times thinner and significantly less resource-intensive to manufacture using new technology for making the artificial materials known as
metasurfaces. These materials consist of
a multitude of interacting nanoparticles
that together can control light. Metasurfaces can be used for optical compo-

nents in portable electronics, sensors,
cameras, or space satellites. The new technology for making such planar surfaces is
based on a plastic that is already used
today to create other microstructures.
The process involves applying a thin
layer of this plastic on a glass plate via spincoating. Using electron-beam lithography,
the desired pattern is drawn in the plastic

film. The metasurface, consisting of pillars of different orientation, is then uncovered with a developer chemical. The resulting device can focus light just like a
normal camera lens but it is thousands of
times thinner and can be flexible.
The phones in our pockets have cameras comparable to a DSLR - technological masterpieces with millions of pix-

Metalenses of
macroscopic scale
can be made
with the technique
The plastic is applied
to a glass plate
via spin-coating

Using electron beam lithography
the desired pattern is drawn in the plastic.
The metasurface consists of pillars
of different orientations, which are then
uncovered with a developer chemical

Metasurfaces
can also be made
as fixable elements

Ultra-thin and flexible metalenses could eventually replace traditional camera lenses. Researchers developed a new and more resource-efficient way
to make metasurfaces. (Illustration: Daniel Andrén and Yen Strandqvist)

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Tech Briefs, February 2021

https://technology.nasa.gov/patent/GSC-TOPS-231 http://www.techbriefs.com http://www.abpi.net/ntbpdfclicks/l.php?202102TBNAV

Tech Briefs Magazine - February 2021

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