Influence of Pulse Duration in Picosecond Laser Ablation of Silicon Nitride Layers

AbstractLasers as production tools offer several advantages, which are especially relevant for the production of solar cells. The contact-less and localized nature of the energy deposition allows new processes, such as laser selective emitter doping, laser ablation of dielectric coatings and via drilling for back contact cell concepts. A highly critical factor is the correct selection of laser parameters and thus laser sources in a manner that adapts the laser process to the requirements of the material, the process nature and the solar cell properties. In this paper the influence of the pulse duration in the range from hundreds of femtoseconds to ten picoseconds on the selective ablation of silicon nitride from multi-crytsalline solar cells is investigated. For this process it is critical to avoid damage to the sensitive emitter and ultra-short laser sources have the potential to enable this process