AFM bending testing of nanometric single crystal silicon wire at intermediate temperatures for MEMS

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This paper focuses on revealing specimen size and temperature effects on plasticity of nanometric self-supported single crystal silicon (Si) wires for the design of high-density electronic and MEMS devices. Mechanical properties of nanometric Si wires were characterized by AFM bending testing at intermediate temperatures ranged from 295 to 573 K in high vacuum. The fabrication process of the nanometric Si wire has been previously reported at MEMS 2000, wherein the elastic properties at room temperature were also investigated by using specimen sizes ranging from nano- to millimeter-scale. This paper investigates elastic-plastic deformation behavior of the nanometric Si wires. Young's modulus of the nanometric Si shows temperature dependence but has no size effect. However, the bending strength, critical resolved shear stress and plastic strain range depend on specimen size and temperature. This research shows for the first time, that it is possible to induce plastic deformation in the nanometric wire at even 373 K, which is close to room temperature. AFM observations show that the slip line density depending on the specimen size and deformation temperature can determine the plastic strain range and the yield point of the nanometric Si wire at the intermediate temperatures.