Impacts of Saw Blade Selection, Dressing and Dicing Parameters on Die Sidewall Quality

Dicing is a critical process step in semiconductor packaging flow to separate wafer into individual chip. Despite the insurgence of new dicing technologies like plasma dicing, stealth dicing and laser full cut, traditional mechanical saw remains the most widely used method because of its low cost of ownership as it is widely used by assembly sites, process maturity, wide selection of equipment and blade offerings. For Wafer Level Chip Scale Packaging (WLCSP), as dicing quality is extremely critical to ensure there is no chipping and crack propagation after unit is being mounted onto customer board, die sidewall quality is usually being inspected during tape and reel process. Besides chipping, cosmetic defect like heavy saw mark will cause overkill and unwanted yield loss. In this paper, we investigated various factors that are affecting die sidewall quality from blade selection, dressing and sawing parameters to reduce chipping and overkill reject. Detailed Failure Analysis (FA) was performed on the defective unit and saw blade. Coupled with detailed analysis on spindle vibration data, these have helped us to nail down the die crack mechanism that correlates to saw blade profile and dressing parameters used. Subsequently, a series of Design of Experiment (DOE) was performed to reduce saw mark overkill rate during tape and reel process sidewall inspection.