Damage-free neutral beam etching for GaN micro-LEDs processing

The neutral beam etching (NBE) technique, which enables damage-free etching of semiconductor materials, is used to fabricate sub-10-μm InGaN/GaN micro-LEDs to replace the conventional inductively coupled plasma etching. In the NBE process, charged particles are neutralized and ultraviolet photons emitted from the plasma are blocked by a carbon aperture placed between the plasma and etching chamber. Only an energy-controlled neutral beam is supplied to the sample surface for etching, which provides damage-free etching. The external quantum efficiency of the fabricated micro-LEDs is almost independent on the chip size, at least down to the chip size of 6 × 6 μm² (smallest device fabricated in this study). This suggests that the NBE process is a very promising technique for fabrication of high-efficiency sub-10-μm InGaN/GaN micro-LEDs required for high-resolution high-brightness micro-LED displays.