Comparison of mechanical characteristics of focused ion beam fabricated silicon nanowires

Abstract

In this study, we investigate the effects of focused ion beam (FIB)-induced damage and specimen size on the mechanical properties of Si nanowires (NWs) by a microelectromechanical system (MEMS)-based tensile testing technique. By an FIB fabrication technique, three types of Si NWs, which are as-FIB-fabricated, annealed, and FIB-implanted NWs, are prepared. A sacrificial-oxidized NW is also prepared to compare the mechanical properties of these FIB-based NWs. The quasi-static uniaxial tensile tests of all the NWs are conducted by scanning electron microscopy (SEM). The fabrication process and specimen size dependences on Young’s modulus and fracture strength are observed. Annealing is effective for improving the Young’s modulus of the FIB-damaged Si. Transmission electron microscopy (TEM) suggests that the mechanism behind the process dependence on the mechanical characteristics is related to the crystallinity of the FIB-damaged portion.

Mechanical Property Measurement of Micro/Nanoscale Materials for MEMS: A Review

“…The strength of Si MEMS structures formed by wet etching is typically higher than that by dry etching even if the specimen size is comparable. FIB processed Si structures include a damaged layer consisting of Ga ion included amorphous Si, which reduces its mechanical reliability [70][71][72][73][74]. Ina et al [72] compared mechanical characteristics of four types of Si nanowires, FIB milled nanowire, annealed FIB milled nanowire, FIB implanted amorphous nanowire, and conventional single crystal Si nanowire.…”

“…FIB processed Si structures include a damaged layer consisting of Ga ion included amorphous Si, which reduces its mechanical reliability [70][71][72][73][74]. Ina et al [72] compared mechanical characteristics of four types of Si nanowires, FIB milled nanowire, annealed FIB milled nanowire, FIB implanted amorphous nanowire, and conventional single crystal Si nanowire. They showed that vacuum annealing was effective for removing Ga clusters from the damaged portion.…”

“…9. Microstructure of FIB-made Si nanowire before and after annealing in high vacuum [72][73][74] In the most case, the damaged layer started recrystallization at the interface to single crystal Si portion, as shown in Fig. 9, and it was changed to poly crystal, not single crystal.…”

Hybrid Silicon Nanowire Devices and Their Functional Diversity

“…[96] In spite of all the efforts made, top-down routes (Figure 3f-i) usually offer a higher yield and device-to-device reproducibility, making them more favorable for mass production. [32] Several lithography techniques exist to define the nanowires: electron beam lithography (EBL), [97][98][99] focused ion beam (FIB), [100] nanoimprint lithography, [101,102] or local oxidation nanolithography using atomic force microscopy. [32] Several lithography techniques exist to define the nanowires: electron beam lithography (EBL), [97][98][99] focused ion beam (FIB), [100] nanoimprint lithography, [101,102] or local oxidation nanolithography using atomic force microscopy.…”

“…These routes involve lithography, etching, and further material deposition steps (Figure f), obtaining a high density of devices with precise design and location, crucial for computer technology . Several lithography techniques exist to define the nanowires: electron beam lithography (EBL), focused ion beam (FIB), nanoimprint lithography, or local oxidation nanolithography using atomic force microscopy . In some cases, they can even compete with bottom‐up methods obtaining sub 20 nm widths, as exemplified by the 8 nm diameter SiNWs in Figure g.…”