Elimination of pillar associated with micropipe of SiC in high-rate inductively coupled plasma etching

Pillar formation in SiC via holes fabricated by inductively coupled plasma etching at a high etch rate in the order of around 2 μm/min using SF6/O2 was studied by comparing samples etched under different thermal conductivity conditions from wafer to carrier. As a result, it was found that the formation of pillars is attributed to a process in which the origin of micropipes acts as a micromask and is passivated with nonvolatile and difficult-to-etch products of NiSiF, which are generated by a chemical combination of the etched Ni from the metal mask and the formed SiFX species during etching. Furthermore, the optimization of etching conditions to eliminate the pillars in SiC via holes with minimal microtrenches was accomplished at a high etch rate of 2 μm/min and high selectivity over 100 for Ni.