Study on machining characteristics of magnetically controlled laser induced plasma micro-machining single-crystal silicon

Laser induced plasma micro-machining (LIPMM) has proved its superiority in micro-machining of hard and brittle materials due to less thermal defects, smaller heat affected zone and larger aspect ratio compared to conventional laser ablation.In order to improve characteristics and stability of induced plasma, this paper proposed magnetically controlled LIPMM (MC-LIPMM) to achieve a good performance of processing single-crystal silicon which is widely used in solid state electronics and infrared optical applications.A comprehensive study on surface integrity and geometrical shape was conducted based on the experimental method. Firstly, the mechanism of MC-LIPMM including laser-plasma, laser-materials interactions and transport effects was theoretically analyzed. Then a series of experiments was conducted to completely investigate the effect of magnetic field intensity, pulse repetition frequency, and bubble behavior on surface integrity and geometrical shape of micro channels.It revealed that magnetic field contributed to maximum reduction of 12.64% for heat affected zone and 62.57% for width while maximum increase of 26.23% for depth and 90.26% for aspect ratio.This research confirms that MC-LIPMM can improve the machining characteristics of silicon materials and cavitation bubbles shows an apparently negative impact on the surface morphology.