Laser machining using an active assist gas

摘要

A silicon workpiece 5 is machined by a laser 2 with a laser beam 4 with a wavelength of less than 0.55 microns by providing a halogen environment for the silicon workpiece to form an active assist gas for laser machining. The laser beam is focussed onto the silicon workpiece at a power density above an ablation threshold of silicon so that the assist gas reacts with the silicon workpiece at or near a focus of the laser beam such that laser machining speed is increased and strength of the machined workpiece is increased due to an improvement in machining quality. The invention has particular application in the dicing of a silicon wafer in the presence of sulphur hexafluoride (SF6), resulting in increased strength of resultant dies.