Comparison of different ultra-short pulsed laser sources used for semiconductor substrate processing

Abstract

Singulation of semiconductor substrates was carried out with ultra-short pulsed laser radiation. Experimental studies were aimed to improve the resulting edge quality by maintaining minimal cut width and sufficient cut depth, in addition to the minimizing of the heat-affected zone and debris generation. Single-pulse ablation thresholds were determined for both laser systems adopted. The influence of various process parameters on wafer processing was studied, and the resulting kerf geometries were investigated by determining the width and the depth obtained in different process conditions. Silicon wafers were processed using two different ultra-short pulsed laser sources with pulse durations 100 fs and 350 fs. Laser radiation was focused onto the wafer surface using three different microscope objectives with numerical apertures in the range NA=0.1–0.4. Irradiation was performed with varying process parameters such as the laser power and the translation speed, as well as by adopting different laser beam scanning strategies. A set of process parameters resulting in a combination of optimal edge quality, kerf geometry and overall ablation rate was identified for each laser system.Singulation of semiconductor substrates was carried out with ultra-short pulsed laser radiation. Experimental studies were aimed to improve the resulting edge quality by maintaining minimal cut width and sufficient cut depth, in addition to the minimizing of the heat-affected zone and debris generation. Single-pulse ablation thresholds were determined for both laser systems adopted. The influence of various process parameters on wafer processing was studied, and the resulting kerf geometries were investigated by determining the width and the depth obtained in different process conditions. Silicon wafers were processed using two different ultra-short pulsed laser sources with pulse durations 100 fs and 350 fs. Laser radiation was focused onto the wafer surface using three different microscope objectives with numerical apertures in the range NA=0.1–0.4. Irradiation was performed with varying process parameters such as the laser power and the translation speed, as well as by adopting different laser beam sca...