Analysis of nonselective plasma etching of AlGaN by CF4/Ar/Cl2

We report the nonselective plasma etching of epitaxial GaN:Mg, Al0.63Ga0.37N, and AlN/Al0.08Ga0.92N short-period superlattices with various doping properties. Etching is performed using mixed CF4 /Ar feed gases in a combined inductively coupled plasma and reactive-ion etching chamber. A uniform etch rate of ,23 nm/min is obtained for each of the compositions studied under identical conditions. This nonselective etching is also found to preserve the surface uniformity studied by atomic force microscopy and quantified using surface roughness and lateral correlation length. By adding Cl2 gas, etch rates are increased to 230–250 nm/min without degrading the surface properties.