Reactive ion etching of vertical GaN mesas by the addition of CH4to BCl3/H2/Ar inductively coupled plasma

Effects of CH 4 addition on the etched profiles were studied during the BCl 3 /H 2 /Ar inductively coupled plasma reactive ion etching of GaN mesas. It was observed that the sidewall angle increases with the addition of up to 10% CH 4 but then decreases with further addition, resulting in a maximum angle of about 86° at the optimum condition, while the etch rate continuously decreases. It was proposed that the improved anisotropy is due to the polymer deposition on the surfaces, which reduces the mask erosion during the etching.