Response surface methodology assisted optimization of ultrafast laser lift-off micro-LEDs

Ultrafast laser lift-off is an important step in manufacturing flexible electronic display devices. To improve the picosecond laser lift-off transfer quality of micro light emitting diodes (micro-LEDs), the response surface methodology (RSM) is employed for the optimization of multiple laser processing parameters, including laser power, scanning speed, spot diameter, and scanning distance. Transfer yield and residual stress are chosen as the performance evaluation metrics, as well as the lifted-off device element composition and transfer quality under different process parameters are characterized. The optimized maximum transfer yield is 95.84% and the minimum residual tensile stress is 0.589 GPa, which is less than 0.5% prediction error of the optimum transfer yield (95.67–95.74%) and residual stress (0.588–0.592 GPa) for ultrafast laser lift-off of micro-LEDs based on the central composite design of RSM, indicating the reliable guidance ability of this model. It develops a new way for quality improvement of the ultrafast laser lift-off process for micro-LEDs.