Laser processing apparatus and wafer producing method

A laser processing apparatus suitable for producing a GaN wafer from a GaN ingot, the laser processing apparatus comprising:

• a chuck table configured to hold the ingot;
• laser beam irradiating means for applying a laser beam having a wavelength capable of passing through the GaN ingot held by the chuck table,
• the laser beam irradiating means including
• a laser oscillator configured to oscillate the laser beam, and
• a condenser configured to form a destruction layer in an interface at a depth corresponding to a thickness of the GaN wafer to be produced, by applying the laser beam oscillated by the laser oscillator while positioning a focusing point of the laser beam within the GaN ingot,
• the laser oscillator including:
• a seeder configured to oscillate a high-frequency pulsed laser,
• a thinning-out unit configured to thin out high-frequency pulses oscillated by the seeder at a predetermined repetition frequency, and generate one burst pulse with a plurality of high-frequency pulses as sub-pulses, and
• an amplifier configured to amplify the generated burst pulse;
• and
• peeling means including a suction piece with vibration applying means said suction piece configured to hold the ingot and said vibration applying means applies vibration to the ingot while said suction piece moves to separate the GaN wafer from the ingot.