Ablation of SiN Passivation Layers on Photovoltaic Cells with Femtosecond Laser Source

This paper presents results of high-speed selective laser ablation of Silicon Nitride (SiN) coatings, which are used as antireflection and passivation layer at monocrystalline and multicrystalline silicon wafers for solar cells. We discuss ablation mechanism of NIR femtosecond laser pulses and advantages for cold ablation with minimised lattice damage. We show practical results of singleshot ablation with a repetition rate of 100 kHz. Finally we compare layer ablation with NIR picosecond laser.