Temperature field modeling and cut formation in laser micromachining of silicon in ice layer

Abstract

Several hybrid laser machining processes have been proposed in recent years to eliminate and/or prevent the deposition of material debris, formation of recast layer and thermal damage in the laser-ablated region. Laser micromachining process performing in an ice layer is a novel technique which is of potential to limit these negative effects in work materials. In this paper, the thermal modeling of the laser ablation in ice is presented to advance the understanding of heat transfer and cut formation induced by the process. A nanosecond-pulse laser was used in this study for grooving a single-crystalline silicon wafer shielded by an ice layer. A 3D numerical simulation associated with the finite element method was performed and then verified by a set of experiments. Phase changes, plasma shielding effect and energy losses caused by thermal conduction and convection were also included in the model. The simulation results obtained under the different levels of laser power were found to have a good agreement with the experiments. The evolution of temperature field and cut formation in the workpiece can be realized at the different heating and cooling cycles of the pulsed laser irradiation. The model developed in this study could facilitate the design and optimization of the ice-assisted laser micromachining process to further advance the ablation of thermally sensitive materials in manufacturing.