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.