Dry Etching of GaN/InGaN Multiquantum Wells Using Inductively Coupled Cl₂/CH₄/H₂/Ar Plasma

Nonselective dry etching of GaN, In_0.12Ga_0.88N, and their multiquantum wells (MQW) was examined using a Cl₂/CH₄/H₂/Ar plasma at room temperature. The etching characteristics were studied as functions of CH₄ concentration, inductively coupled plasma power, and radio frequency table power. Nonselective etching of MQW using a Cl₂/CH₄/H₂/Ar plasma was monitored by means of laser interferometric reflectance. Ga, In, and GaCl as well as CN were observed as group III and group V etch products, respectively, in the optical emission spectrum during plasma etching. By optimizing the CH₄ concentration in the gas mixture, the roughness on the etched surface and the sidewall of the MQW could be substantially reduced. These results indicate that Cl₂/CH₄/H₂/Ar plasma chemistry, combined with a postannealing process for etch-damage recovery, is suitable for the fabrication of optoelectronic devices using GaN, InGaN, and GaN/InGaN MQW.