Via Hole Formation in Silicon Carbide by Laser Micromachining
A 248 nm (KrF) excimer laser with a repetition rate of 10 Hz, pulse duration of 30 ns and beam energy up to 450 mJ was employed to form vias in 4H-SiC substrates and Lely platelets. SEM micrographs have been used to evaluate etched material quality as well as etch rate. The area surrounding the via-holes is covered by nanoparticles, which are debris from the laser ablation and are removed by chemical cleaning and agitation. The etch-rate exhibits a perfect linear behaviour versus the number of laser pulses showing the possibility of an all-laser via-hole formation. A slight tapering along the via-holes, useful for the subsequent metallization process is also observed. Finally, a defective,15 μm wide, zone is formed nearby the sidewalls.
Robert P. Devaty, David J. Larkin and Stephen E. Saddow
K. Zekentes et al., "Via Hole Formation in Silicon Carbide by Laser Micromachining", Materials Science Forum, Vols. 527-529, pp. 1119-1122, 2006