Failure analysis of micron scaled silicon under high rate tensile loading
Abstract
Structures have been built at micrometer scales with unique failure mechanism not yet well understood, in particular under high-rate loading conditions. Consequently, MEMS devices suffer from inconsistent performance and insufficient reliability. This research aims at understanding the failure mechanisms in micro-scaled specimens deforming at high rates. Single crystal silicon micro-specimens that are 4 microns thick are subjected to tensile loading at average strain rates of 100 s-1 using a miniature modified Kolsky tension bar. A capacitance displacement system and piezoelectric load cell are incorporated to measure the strain and stress of the silicon micro-specimens directly to ensure precision. Extreme fragmentation of the specimens occurs during failure and this phenomenon is observed using a high speed camera. A debris retention system is used to capture the silicon fragments for direct inspection using a Scanning Electron Microscope. The failure mechanism of the micro-specimens is attributed the presence of sub micron scaled surface defects rather than any one large critical flaw.
Degree
Ph.D.
Advisors
Chen, Purdue University.
Subject Area
Engineering|Materials science
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