RESIDUE-FREE REACTIVE ION ETCHING OF 3C-SIC AND 6H-SIC IN FLUORINATED MIXTURE PLASMAS

We report on residue-free reactive ion etching (RIE) of 3C-SiC and 6H-SiC in mixtures of fluorinated gases consisting of a primary (CHF3) and a secondary gas (CF4, NF3, and SF6). The corresponding etch rate, etched surface morphology, anisotropic profile, and process reproducibility are obtained at different levels of CHF3. The advantage of this approach is to eliminate gas additives (H-2 and O-2) while maintaining the residue-free RIE and high process portability The effect of SiC doping concentration and dopant type on obtaining residue-free RIE is reported along with the effects of plasma pressure and RF power. Etching mechanisms, plasma chemistry, and optimized etching conditions are also discussed.