Mechanism investigation of ductility improvement in heat-assisted nanocutting of single crystal silicon

Abstract

Single crystal silicon, which is widely used in multiple fields, is a typical difficult-to-machine material due to its hardness and brittleness. It has been demonstrated that elevated temperatures improve the ductility of single crystal silicon. However, the underlying mechanism of ductility improvement remains unclear, thereby constraining the advancement of ultra-precision cutting technology for single crystal silicon. In this study, a heat-assisted device with a heated tool is developed and utilized in the nanocutting of single crystal silicon. The scratch morphology indicates that the application of heat assistance up to 200 °C can enhance the brittle-to-ductile transition depth in single crystal silicon. Raman spectroscopy and transmission electron microscopy (TEM) were employed to examine the subsurface damage in the scratch. Furthermore, molecular dynamics (MD) simulations were conducted to elucidate the formation of chips and subsurface damage during heat-assisted nanocutting of single crystal silicon. By integrating the experimental and simulation results, it is evident that elevated temperatures enhance the ductile cutting of single crystal silicon by reducing the shearing resistance of amorphous silicon and promoting dislocations and slips in the single crystal substrate.