Siナノワイヤの機械物性評価と加工プロセス効果

Abstract

In this study, we report on four types of fabrication methods for Si nanowires (NWs) using focused ion beam (FIB), annealing and sacrificial oxidation techniques. FIB was used for directly fabricating Si NWs (Type A) from SON (silicon on nothing) membrane. The NWs were annealed at 700°C for 60min in high vacuum to remove implanted Ga ions and to recrystallize FIB-induced affected layer (Type B). Ga ions were implanted on Si surface using FIB to make Si NW pattern, followed by TMAH anisotropic wet etching (Type C). The Type D NWs were fabricated by anisotropic wet etching and repeated sacrificial oxidation techniques. To measure the mechanical property of all types of Si NWs, we conducted MEMS-based tensile device. In the Type A NWs, the Young's modulus ranged from 107 to 144GPa, which were lower than the ideal value, 169GPa, for Si (001) [110]. The Young's modulus of type B NWs were almost identical to the ideal value. The Type C NWs exhibited the Young's modulus ranging from 98 to 108GPa, corresponding to the modulus for amorphous Si. The fracture strength data were ranging from 2.3 to 8.2 GPa. The strongest was Type D NWs.