In-situ laser beam position and spot size sensor and high speed scanner calibration, wafer debonding method

A wafer debonding apparatus, comprising:

• a laser scanning system configured to provide a scan laser beam;
• a laser beam sensing system located outside a wafer for aligning the scan laser beam on the wafer,
• wherein at least one laser beam sensor of the laser beam sensing system comprises, the at least one laser beam sensor being adjacent to one of opposing edges of the wafer:
• a first optical slit configured to pick up, at a first position of a laser scan line, the scan laser beam and guide the laser beam to a photodetector;
• a second optical slit configured to pick up, at a second position of the laser scan line, the scan laser beam and guide the laser beam to the photodetector;
• a third optical slit configured to pick up, at a third position of the laser scan line, the scan laser beam and guide the laser beam to the photodetector;
• the photodetector configured to convert the laser beam guided through the first to third optical slits to first to third electrical pulses, respectively;
• and
• at least one processor configured to determine a spot size of the scan laser beam based on a laser scan speed and a temporal width of the first electrical pulse and determine a position of the scan laser beam based on a time difference between the second and third electrical pulses, and
• wherein positions of the second optical slit and the third optical slit relative to the wafer are known to the at least one processor.