Inductively Coupled Plasma Etching of GaAs with High Anisotropy for Photonics Applications

Inductively Coupled Plasma Reactive Ion Etching (ICPRIE) of Gallium Arsenide (GaAs) using BCl3/Cl-2/Ar plasma was carried out for Photonic Crystal (PhC) applications. The recipe was optimized by varying various etch parameters. While the addition of N-2 improved sidewall angle, the surface roughness increased for N2 flow rate beyond I seem. An optimized BCl3/Cl-2/Ar/N-2 recipe with flow rate 6/1/11/1 sccm was used to etch holes in GaAs. For 4 mu m diameter circular pattern, etch rate of about 556 nm/min with a sidewall angle of 86 degrees and surface roughness of the order 1 nm were obtained.