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

Abstract

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.