One more from Aftab (in AIP Advances)!
7/9/2016
News Details
Well, we should have
asked Aftab to write a few more! This time in AIP Advances.
Design criteria for XeF2 enabled deterministic transformation of bulk silicon
(100) into flexible silicon layer
Aftab M. Hussain1, Sohail F. Shaikh1, Muhammad M. Hussain
Isotropic etching of bulk silicon (100) using Xenon Difluoride (XeF2) gas
presents a unique opportunity to undercut and release ultra-thin flexible
silicon layers with pre-fabricated state-of-the-art Complementary Metal Oxide
Semiconductor (CMOS) electronics. In this work, we present design criteria and
mechanism with a comprehensive mathematical model for this method. We consider
various trench geometries and parametrize important metrics such as etch time,
number of cycles and area efficiency in terms of the trench diameter and
spacing so that optimization can be done for specific applications. From our
theoretical analysis, we conclude that a honeycomb-inspired hexagonal
distribution of trenches can produce the most efficient release of ultra-thin
flexible silicon layers in terms of the number of etch cycles, while a
rectangular distribution of circular trenches provides the most area efficient
design. The theoretical results are verified by fabricating and releasing
(varying sizes) flexible silicon layers. We observe uniform translation of design
criteria into practice for etch distances and number of etch cycles, using
reaction efficiency as a fitting parameter.
An important paper on our trench-protect-release-reuse process mechanism - how
one can use analytics to design a successful flexing process.
In a sense this is Sohail's first paper from our group too! Hopefully he
carries the baton from Aftab successfully!