Waterjet-guided laser addresses particle generation in semiconductor dicing

摘要

Separating semiconductors has always been a challenge for laser-based cutting techniques. Until recently, the standard process for dicing semiconductor wafers was abrasive sawing, which has been optimized for this application over more than two decades. However, the demands of emerging types of semiconductor devices, like those based on thin wafers and on compound semiconductors, can no longer be fulfilled by abrasive sawing. New separation methods are needed. The waterjet-guided laser showed some years ago to be a good alternative for dicing and free-shape cutting of thin semiconductors, including gallium arsenide (GaAs), and has been recently qualified in terms of particle generation. Indeed, particle generation and redeposition are important problems for all conventional cutting processes. Particles and dust (between 0.1 and 5 μm) are spread over the surface of the workpiece during the process, especially in the case of laser-based technologies. Small particles are difficult to clean as the adhesion forces (such as capillary, electrostatic and Van der Waals) are strong compared to the force that can be applied by a wiping or rinsing device. Ad- ditionally, in conventional laser cutting, droplets of molten material are "soldered" to the surface of the workpiece.