Fabrication of SiC micro-lens by plasma etching

SiC micro-lenses were fabricated by a plasma etching method by controlling the etch selectivities between photoresist and SiC. To etch SiC, inductively coupled plasmas were used with CF₄, HCl, and HCl/HBr as the etch gases. When CF₄ and HCl were used to etch SiC, the etch selectivities of SiC over photoresist were remained near 0.4 and 0.6, respectively. However, by using HCl/HBr, the selectivity was changed from 0.6 to 1.1. The SiC etch rates for HCl/HBr were in the range from 345 to 500 nm/min. The curvature radius of SiC micro-lenses fabricated with HCl/HBr was in the range from 20 to 27.54 μm and the roughness of the fabricated lenses was in the range from 1.7 to 2.65 nm.