Tensile Strength of Silicon Nanowires Batch-Fabricated into Electrostatic MEMS Testing Device

The tensile strength of a silicon nanowire (SiNW) that had been integrated into a silicon-on-insulator (SOI)-based microelectromechanical system (MEMS) device was measured using electrostatic actuation and sensing. SiNWs of about 150 nm diameter and 5 m length were batch-fabricated into a 5-m-thick SOI device layer. Since there was no interface between the SiNW and the MEMS device and the alignment was perfect, the SiNW integration into an SOI-MEMS was expected to be useful for developing highly sensitive biochemical sensors or highly reliable torsional mirror devices. The SiNW was tensile tested using the electrostatic MEMS testing device. The integration was achieved using a combination of anisotropic and an isotropic dry etching of silicon, with an inductively coupled plasma reactive ion etching. A fabricated silicon beam of 800 nm square was thinned by a sacrificial oxidation process. The tensile strength of the wire was 2.6-4.1 GPa, which was comparable to that of microscale silicon MEMS structures. The reliability of such a thin device was successfully verified for future applications of the device structures.