Suppression of backside damage in nanosecond internal-focusing pulse laser dicing with wavefront modulation

Laser dicing with tightly focused nanosecond pulsed laser light inside a semiconductor wafer is a dry, debris-free dicing method achieved by the generation of thermal microcracks. This method has two practical issues: a dicing speed that is limited by the repetition rate of the pulsed laser and potential damage to integrated circuits on the wafer from excessive laser intensity due to insufficient beam divergence. By correcting aberrations and generating multiple beams via wavefront modulation, multiple focused beams inside the wafer will become sufficiently divergent to avoid undesirable potential laser damage. We confirmed these improvements by dicing sapphire wafers with a pulsed laser and a high-numerical-aperture objective lens. (C) 2017 Society of Photo-Optical Instrumentation Engineers (SPIE)