GaAs-Wafer Dicing Using the Water jet Guided Laser

摘要

Semiconductor wafers are getting thinner and thinner. GaAs wafers are not excluded by this trend. Since new dicing technologies are required for wafer thicknesses less than 150 μm. Significant differences are noted among existing dicing methods. Abrasive sawing does not provide the desired cutting speed and yield because of mechanical damage (cracking, chipping). Cutting with conventional lasers should be avoided because of significant heat damage and safety issues (arsenic oxides). The Laser-Microjet, which combines a laser and a water jet, is currently the most promising technology for thin wafer dicing. It is faster and cleaner than any other process on thin GaAs wafers and generates an impressive kerf quality. The water jet, combined with a thin water film on the wafer surface, removes any deposition generated by laser ablation. No toxic gas is emitted, since all toxic material is carried away by water. The Laser-Microjet also allows omnidirectional cutting, which is impossible with blades. Specifically, it can cut at 45° to the crystal plane. Edge grinding of thin wafers represents one application of omni-directional cutting, reducing breakage by removing the sensitive wafer edge containing micro-cracks.