Molecular dynamics study of cutting characteristics of monocrystalline silicon under laser-ultrasonic elliptical...

To investigate the effects of machining methods on the cutting behavior and microstructure evolution of monocrystalline silicon, molecular dynamics (MD) models of traditional cutting (TC), laser-assisted cutting (LAC), ultrasonic elliptical vibration cutting (UEVC), and laser-ultrasonic elliptical vibration cutting (L-UEVC) were established. Cutting force, material removal behavior, stress distribution, phase transformation, and subsurface damage were analyzed. The results show that both laser-induced thermal softening and ultrasonic intermittent cutting effectively reduce cutting forces. L-UEVC exhibits the lowest cutting force and the highest material removal efficiency. Stress analysis indicates that the coupled energy field suppresses stress penetration into the subsurface, thereby reducing machining-induced damage. The hybrid field promotes atomic rearrangement and inhibits irreversible amorphization, thereby improving crystal integrity. Compared with TC, the subsurface damage layer (SDL) thickness under L-UEVC is reduced by 26.86%, significantly enhancing surface integrity. These findings clarify the atomic-scale mechanism of laser-ultrasonic coupling in regulating silicon deformation and damage evolution, providing guidance for high-quality semiconductor machining.

The cutting behavior and microstructure evolution of monocrystalline silicon under four typical processing conditions of TC, LAC, UEVC, and L-UEVC were systematically studied using MD simulations with the Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS). The interactions among Si-Si, C-C, and Si-C atoms were described using the Tersoff potential. The effects of laser-induced thermal softening and ultrasonic intermittent cutting on material removal behavior, cutting force, stress distribution, phase transformation, and subsurface damage evolution were analyzed using OVITO software.