Direct tensile testing of sub-100nm-size silicon nanowires fabricated by fib-sampling of SON membranes

This paper describes the effects of specimen size, focused ion beam (FIB) damage, and annealing on the mechanical properties of sub-100nm-size silicon (Si) nanowires (NWs) evaluated by direct tensile testing. Si NWs were made from silicon-on-nothing (SON) membranes that were produced by deep reactive ion etching (DRIE) trench fabrication and ultra-high vacuum (UHV) annealing. FIB system´s probe manipulation and film deposition functions were used to fabricate Si NWs and to directly bond them onto the sample stage of a tensile test device. The mean Young´s modulus and strength of FIB-damaged NWs were found to be 131.0GPa and 5.6GPa, respectively. After 1000°C annealing in UHV, the Young´s modulus was increased to 169.2GPa, whereas the strength was decreased due to morphology degradation. The combination of FIB system´s sampling and UHV annealing will enable us to challenge accurate evaluation of 10nm×10nm cross-sectional Si NWs and to obtain true size effect (without process effect) on the mechanical characteristics in near future.