Characteristics of GaN thin films by inductively coupled plasma etching with Cl2/BCl3 and Cl2/Ar

GaN thin films were etched by inductively coupled plasma (ICP). The effects of BCl3 and Ar with different Cl2 fraction are studied and compared. The ICP power and RF power are also altered to investigate the different effects by using Cl2/BCl3 or Cl2/Ar as etching gases. The etch rate and surface morphology of the etched surface are characterized by using surface profiler, scanning electron microscopy and atomic force microscopy. The root-mean-square roughness values are systematically compared. It is found that the etch rates of Cl2/Ar are higher than that of the Cl2/BCl3 in the Cl2 fraction ranging from 10 to 90%. When the ICP power is increased, the RMS roughness of GaN surface after ICP etching shows reverse trend between Cl2/BCl3 and Cl2/Ar gas mixture. The results indicate quite different features using Cl2/BCl3 and Cl2/Ar for GaN ICP etcing under the same conditions.