Abstract

Sapphire substrates are widely used for the manufacturing of blue and green LEDs and diode lasers. Dicing of sapphire wafers with deposited GaN device structures is therefore an important technological challenge. During the last ten years the dicing efficiency has been investigated for a wide range of wavelengths from DUV (157nm) to UV (355nm); pulse widths (in nanosecond regime); beam shaping; and power levels [1]. Traditionally, some industrial sapphire dicers use nanosecond pulses with a wavelength of 355 nm. In this configuration, the laser cutting is performed through the back side of the sapphire wafer. Furthermore, nanosecond pulses with a wavelength of 266 nm are used for cutting from the front (the side with the structure) of the wafer. A few attempts to dice with a green laser, also in Q-switched regime, emitting pulses with a width of a few tenths of a nanosecond have been reported in the literature [1, 2]. Recently the first Q-switched infrared pulsed lasers generating ten picosecond pulses at a wavelength of 1060/532 nm were presented on the market.

© 2015 IEEE