Study on the Vertical Ultrasonic Vibration-Assisted Nanomachining Process on Single-Crystal Silicon

Abstract

Subsurface damage that is caused by mechanical machining is a major impediment to the widespread use of hard–brittle materials. Ultrasonic vibration-assisted macro- or micromachining could facilitate shallow subsurface damage compared with conventional machining. However, the subsurface damage that was induced by ultrasonic vibration-assisted nanomachining on hard–brittle silicon crystal has not yet been thoroughly investigated. In this study, we used a tip-based ultrasonic vibration-assisted nanoscratch approach to machine nanochannels on single-crystal silicon, to investigate the subsurface damage mechanism of the hard–brittle material during ductile-machining. The material removal state, morphology, and dimensions of the nanochannel, and the effect of subsurface damage on the scratch outcomes were studied. The materials were expelled in rubbing, plowing, and cutting mode in sequence with an increasing applied normal load and the silicon was significantly harder than the pristine material after plastic deformation. Transmission electron microscope analysis of the subsurface demonstrated that ultrasonic vibration-assisted nanoscratching led to larger subsurface damage compared with static scratching. The transmission electron microscopy results agreed with the Raman spectroscopy and molecular dynamic simulation. Our findings are important for instructing ultrasonic vibration-assisted machining of hard–brittle materials at the nanoscale level.

Fabrication of Chiral Nanostructures through Vibration-Assisted Scratching Combined with Wet Etching for Surface-Enhanced Raman Scattering Substrates

“…The subsurface damage induced by UVAS was much larger than the subsurface damage induced by CS due to the higher material-disorder energy. 35 UVAS generated a thicker α-Si than CS, leading to a deeper UVAS groove than the CS groove after etching. Obviously, a deep nanogroove also can be machined by CS with a higher force.…”

“…Furthermore, tipbased ultrasonic vibration-assisted scratching (UVAS) could facilitate the machined depth compared with conventional scratching (CS). 35 The large normal load is the reason for the deeper machined depths. However, the relatively large normal load may contribute to tip wear, which does not benefit longdistance machining.…”

“…However, the depth-to-width ratio of the machined nanostructures is fixed due to the limitation of the tip shape, which is unsuitable for improving their performance. Furthermore, tip-based ultrasonic vibration-assisted scratching (UVAS) could facilitate the machined depth compared with conventional scratching (CS) . The large normal load is the reason for the deeper machined depths.…”

Scanning Probe Lithography: State-of-the-Art and Future Perspectives

“…Mechanical scanning probe lithography (M-SPL) prompts the selective removal of materials from the substrate surface by several nN mechanical forces applied at the probe using ploughing, milling, and cutting via atomic-force microscope (AFM) [127][128][129]. To sum up, this technique can be categorized into two work types depending on the AFM scanning mode.…”

“…This process is called static ploughing lithography, as shown on the left side of Figure 22. When AFM works in the tapping mode, as illustrated on the right side of Figure 22, a bigger amplitude applied on the cantilever makes the cantilever achieve its resonant Mechanical scanning probe lithography (M-SPL) prompts the selective removal of materials from the substrate surface by several nN mechanical forces applied at the probe using ploughing, milling, and cutting via atomic-force microscope (AFM) [127][128][129]. To sum up, this technique can be categorized into two work types depending on the AFM scanning mode.…”