Laser micromachining of silicon substrates: Investigation and utilisation of assist media

The use of short and ultrashort pulse lasers for laser micromachining of silicon is now a well advanced manufacturing technique. Applications include semiconductor wafer dicing, inkjet printhead slotting, and substrate structuring for solar cell production. A key element of the laser machining process is the role of the ambient or assist media in relation to enhancing the ablation rate, minimising the negative impact of debris generation, and functionalising the laser generated particulate. This paper will present results of research work focused on the impact of assist media, in particular the use of water, non-polar liquids, and halocarbon gases, in laser micromachining of silicon. Novel observations related to the laser induced liquefaction of assist gases will also be presented.