Bow Reduction of AlInGaN-Based Deep UV LED Wafers Using Focused Laser Patterning

Abstract

We investigated the effect of bow reduction of AlInGaN-based deep-ultraviolet light-emitting diode (DUV LED) wafers using internally focused laser patterning. The laser-induced stress inside of the sapphire substrate was found to increase with increasing density of laser lines and decreasing distance of the laser lines to the back surface of the sapphire substrate. By adjusting the laser process, the convex bow of DUV LED wafers could be almost completely eliminated. This bow reduction resulted in an improved uniformity of the LED forward voltage across the wafer compared to the reference wafer without laser patterning.