A novel patterning effect during high frequency laser micro-cutting of hard ceramics for microelectronics applications
Résumé
This paper investigates the laser micro-cutting of wide band gap materials for microelectronics industry purposes. An ultraviolet (355 nm) diode-pumped solid-state (DPSS) nanosecond laser was used in this investigation. The laser energy varied from 7 to 140 ﰶJ/pulse with typical frequencies from 40 to 200 kHz. The effect of pulse energy and scanning speed on the depth of the cutting street of ﰼ-Al2 O3 and glass was studied. Typical depths of 200 ﰶm were achieved on ﰼ-Al2 O3 for 140 ﰶJ/pulse, 40 kHz at 13 mm/s. SEM images showed periodic patterns produced by periodic explosive boiling that can influence the achieved depth. The shape, size and periodicity of the recast material depended on the feed rate and the laser beam frequency. This periodic removal mechanism seems to be specific to dielectrics since it was not observed for semiconductors such as silicon or silicon carbide.