Etching selectivity and surface profile of GaN in the Ni, SiO2 and photoresist masks using an inductively coupled plasma

The selectivity and etched surface profile for etching GaN using an inductively coupled plasma (ICP) in Ni, SiO2 and photoresist masks were investigated. The mask etching rates ir the Ni, SiO2 and photoresist masks were 26, 70 and 245 nm/min, respectively, for a RF power of 500 W, an ICP power of 600 W and an etching gas ratio of BCl3/Ar/N-2 = 15 : 5 : 10(sccm). A high selectivity of 15 in the Ni mask was found to be higher than that of 5.6 and 1.65 in the SiO2 and photoresist masks, respectively. The best etching surface profile was also obtained in the Ni mask in comparison with the SiO2 or photoresist mask.