Manufacture of Antireflection Silicon Microstructures by Nanosecond Pulsed Laser Micromachining

Laser surface texturing is a promising method to functionalize surfaces by changing chemical, physical, and mechanical properties of materials at the microscopic scale. In the present chapter, we perform finite element simulations and experiments to investigate the ablated surface morphology of silicon by nanosecond pulsed laser ablation using low laser fluences ranging from 14.92 to 23.21 J/cm². The utilized finite element model comprehensively considers the following aspects: (1) combined effects of thermal conduction, convection, and radiation on heat conduction; (2) temperature-dependent thermomechanical properties of material; (3) instantaneous update of the laser focus due to evaporation-induced surface recession; and (4) spatial and temporal Gaussian energy distributions of the laser pulse. Experimental works using the same laser processing parameters with the conducted finite element simulations are carried out to validate the simulation results. Through the optimization of the laser processing parameters by 2D and 3D finite element simulations and the respective experimental validations for eliminating heat-affected zone and promoting forming accuracy, high accuracy aligned microgrooves are fabricated on silicon with high antireflective properties in a wide range of wavelengths between 400 and 2000 nm. This is fairly comparable with the performance of similar silicon microstructures manufactured by femtosecond laser ablation. Consequently, the current chapter presents a feasible way to fabricate precise surface microstructures with high antireflective properties on silicon at low cost by nanosecond pulsed laser ablation.