Rate-controlled cycle etching of GaN by cycle exposure to BCl3 and F2-added Ar plasma at a substrate temperature of 400 °C

Cycle etching of GaN with high etching rate controllability was achieved by cycle exposure to BCl3 gas and F2-added Ar plasma at an ion energy of 23 eV and a substrate temperature of 400 °C. Surfaces chlorinated by exposure to BCl3 gas were removed by ion bombardment during exposure to the F2-added Ar plasma. By controlling the plasma irradiation time, the etching amount per cycle for GaN can be regulated. Because of the lower energies of ion bombardments, no degradation of the cathodoluminescence intensity attributable to the energy bandgap edge of GaN was observed after cycle etching.