Lift-off method

A lift-off method for transferring an optical device layer in an optical device wafer to a transfer substrate, said optical device layer being formed on a front side of an epitaxy substrate through a buffer layer, said lift-off method comprising:

• a transfer substrate bonding step of bonding said transfer substrate through a bonding layer to a front side of said optical device layer of said optical device wafer, thereby forming a composite substrate;
• a buffer layer breaking step of applying a pulsed laser beam having a wavelength transmissive to said epitaxy substrate and absorptive to said buffer layer from a back side of said epitaxy substrate to said buffer layer after performing said transfer substrate bonding step, thereby breaking said buffer layer;
• and
• an optical device layer transferring step of peeling said epitaxy substrate from said optical device layer after performing said buffer layer breaking step, thereby transferring said optical device layer to said transfer substrate;
• wherein ultrasonic vibration is applied to said composite substrate in performing said optical device layer transferring step.