Optimization of diode pumped solid state ultraviolet laser dicing of silicon carbide chips using design of experiment methodology

This paper investigates the laser micromachining of SiC-4H wafers with an ultraviolet (355 nm) nanosecond source. The design of experiment methodology was used to study the effect of pulse energy, number of passes, defocus, and scanning speed on scribing depth and was modeled with Design Expert® software. Pulse energy and scanning speed were found to have a significant effect on scribe depth (by a factor of 10 compared to defocus), while the effect of the number of passes varied with pulse energy and scanning speed. The model predicted a narrow set of processing parameters to scribe half of the wafer thickness (180/360 μm). A more fundamental study was also conducted in order to validate literature observations on the ablation mechanism. A brief comparison between conventional blade dicing and the laser scribe-break method was performed on a 3 in. diameter wafer. It was discovered that a possible gain of gross die (number of usable chips per wafer) of 7% could be achieved which could provide a useful economic benefit.