Comparison of F-2 plasma chemistries for deep etching of SiC

A number of F-2-based plasma chemistries (NF3, SF6, PF5, and BF3) were inve stigated for high rate etching of SiC. The most advantageous of these is SF 6, based on the high rate (0.6 mum min-l) it achieves and its relatively lo w cost compared to NF3. The changes in electrical properties of the near-su rface region are relatively minor when the incident ion energy is kept belo w approximately 75 eV. At a process pressure of 5 mtorr, the SiC etch rate falls-off by similar to 15% in 30 mum diameter via holes compared to larger diameter holes (>60 mum diameter) or open areas on the mask. We also measu red the effect of exposed SiC area on the etch rate of the material.