Design criteria for XeF2 enabled deterministic transformation of bulk silicon (100) into flexible silicon layer
KAUST DepartmentComputer, Electrical and Mathematical Sciences and Engineering (CEMSE) Division
Electrical Engineering Program
Integrated Nanotechnology Lab
Integrated Disruptive Electronic Applications (IDEA) Lab
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AbstractIsotropic 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.
CitationDesign criteria for XeF2 enabled deterministic transformation of bulk silicon (100) into flexible silicon layer 2016, 6 (7):075010 AIP Advances
SponsorsThis publication is based upon work supported by the King Abdullah University of Science and Technology (KAUST).