Very Low Pressure Magnetron Reactive Ion Etching of GaN and AlxGa1−xN Using Dichlorofluoromethane (Halocarbon 12)

In this work we report on the magnetron reactive ion etch (MRIE) technology for gallium nitride (GaN) and aluminum gallium nitride (AlxGa1−xN) using dichlorodifluoromethane (CCl2F2), commonly known as halocarbon 12, with etch rates greater than 1,000 and 840 Å/min, respectively. Magnetic confinement of a very low pressure (10−4 Torr range) radio frequency (RF) discharge generates high-density plasmas, with low sheath voltages at the bounding surfaces, and very high dissociation of the source gas. Furthermore, the very low pressure of the etch process is characterized by long mean free paths so that sputtering contamination is reduced. MRIE chemistry has been monitored in situ by means of mass spectroscopy. Finally, we report on the successful fabrication of an indium gallium nitride (InxGa1−xN) blue light emitting diode (LED), whose fabrication sequence included the MRIE etching of GaN in CCl2F2.