Assessing failure in epitaxially encapsulated micro-scale sensors using micro and nano x-ray computed tomography


Millions of micro electro mechanical system sensors are fabricated each year using an ultra-clean process that allows for a vacuum-encapsulated cavity. These devices have a multi-layer structure that contains hidden layers with highly doped silicon, which makes common imaging techniques ineffective. Thus, examining device features post-fabrication, and testing, is a significant challenge. Here, we use a combination of micro- and nano-scale x-ray computed tomography to study device features and assess failure mechanisms in such devices without destroying the ultra-clean cavity. This provides a unique opportunity to examine surfaces and trace failure mechanisms to specific steps in the fabrication process.

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This work was supported by the Defense Advanced Research Projects Agency (DARPA) Precision Navigation and Timing program (PNT) managed by Dr. Ron Polcawich under contract # N66001-12-1-4260. The fabrication work was performed at the Stanford Nanofabrication Facility (SNF), which was supported by the National Science Foundation through the National Nanotechnology Infrastructure Network under Grant ECS-9731293. The author would also like to thank the National Science Foundation and the Graduate Research Program (NSF-GRFP). Use of the Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, is supported by the US Department of Energy Office of Science, Office of Basic Energy Sciences under Contract No. DE-AC02-76SF00515.

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Correspondence to Lizmarie Comenencia Ortiz.

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Ortiz, L.C., Heinz, D.B., Flader, I.B. et al. Assessing failure in epitaxially encapsulated micro-scale sensors using micro and nano x-ray computed tomography. MRS Communications 8, 275–282 (2018).

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