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/Cl2/Ar plasma was carried out for Photonic Crystal (PhC) applications. The recipe was optimized by varying various etch parameters. While the addition of N2 improved sidewall angle, the surface roughness increased for N2 flow rate beyond 1 sccm. An optimized BCl3/Cl2/Ar/N2 recipe with flow rate 6/1/11/1 sccm was used to etch holes in GaAs. For 4 μm diameter circular pattern, etch rate of about 556 nm/min with a sidewall angle of 86° and surface roughness of the order 1 nm were obtained.