Page 07/12/2016 20:11:16

One more from Aftab (in AIP Advances)!

7/9/2016
‚ÄčWell, 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!