Line beam laser lift-off approach for sapphire removal

Gallium nitride (GaN) layers grown on sapphire substrate wafers have been successfully separated using a novel line beam laser lift-off (LLO) approach. The absorption of the 248nm excimer laser radiation by the GaN through the sapphire wafer results in the formation of metallic gallium and nitrogen gas. The sapphire wafer was easily removable by heating above the Gallium melting point. The metallic Gallium phase has been inspected via diverse microscopic surface analysis techniques after line beam laser lift-off processing. The measurements indicate that the sapphire separation process using line beam laser scanning has only a marginal impact on the structural quality of the GaN layer. The line beam LLO results are compared with conventional square field LLO processing results and are evaluated in view of aptness for mass production of high brightness light emitting diodes (HB-LEDs).