LASER LIFT-OFF METHOD AND LASER LIFT-OFF APPARATUS

摘要

PROBLEM TO BE SOLVED: To peel a material layer from a substrate securely without causing any cracking in laser lift-off processing.SOLUTION: A pulse laser emitted from a laser source 20 is irradiated to a workpiece W through a laser optical system 40 to peel a material layer (GaN crystal layer) from a sapphire substrate. Pulse waveform of the laser is measured by a pulse waveform measuring instrument 70 and transmitted to a control part 50. A calculation part 501 converts the laser pulse waveform to output power (W) and calculates an energy amount (available energy) from rising of the laser pulse to a time T based on the time T from rising of the laser pulse input by an input part 502 to a time when temperature of GaN becomes the highest and the laser pulse waveform. The available energy is compared with target available energy, a signal according to the difference is fed back to the laser source 20, and the available energy is controlled to correspond to the target available energy.