HIGH-TEMPERATURE ELECTRON-CYCLOTRON-RESONANCE ETCHING OF GAN, INN, AND ALN

Electron cyclotron resonance etch rates for GaN, InN, and AlN are reported as a function of temperature for Cl2/H2/CH4/Ar and Cl2/H2/Ar plasmas. Using Cl2/H2/CH4/Ar plasma chemistry, GaN etch rates remain relatively constant from 30 to 125°C and then increase to a maximum of 2340 Å/min at 170°C. The InN etch rate decreases monotonically from 30 to 150°C and then rapidly increases to a maximum of 2300 Å/min at 170°C. This is the highest etch rate reported for this material. The AlN etch rate decreases throughout the temperature range studied with a maximum of 960 Å/min at 30°C. When CH4 is removed from the plasma chemistry, the GaN and InN etch rates are slightly lower, with less dramatic changes with temperature. The surface composition of the III-V nitrides remains unchanged after exposure to the Cl2/H2/CH4/Ar plasma over the temperatures studied.© 1995 American Institute of Physics.