Fracture of silicon at low length scales
October 1-6, 2017
At small length scales, perhaps no material is more industrially important than silicon. It enabled the information age, and micro-electro-mechanical systems (MEMS) made of silicon are increasingly integrated into our daily lives via smartphones. Classically, silicon is known as a brittle material, whose sharp brittle-ductile transition (BDT) occurs within a matter of one or two degrees Celsius at a temperature between 500 and 800 °C depending on the microstructure, strain rate, and crystal orientation . However, recent advances in sample miniturization has revealed that plastic compressive deformation can occur in silicon at room temperature if the sample size is reduced below 400 nm . This raised the question of whether silicon’s intrinsic fracture toughness also changed at reduced length scales. The development of many new micro-geometries for measurement of fracture toughness allowed this question to be comprehensively answered for the micron length scale – with the answer being no . However, this didn’t necessitate that the BDT was unaffected.
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Jeffrey M. Wheeler, "Fracture of silicon at low length scales" in "Nanomechanical Testing in Materials Research and Development VI", Karsten Durst, Technical University of Darmstadt, Germany Eds, ECI Symposium Series, (2017). http://dc.engconfintl.org/nanomechtest_vi/112