Jun-Woo Lee

Etch Properties Of Gallium Nitride Using Chemically Assisted Ion Beam Etching (CAIBE)

Dry etching properties of GaN were investigated using chemically assisted ion beam etching (CAIBE) with Cl2, BCl3, and HCl gases. The measured GaN etch rate with increasing tilt angle showed the maximum at a 30° tilt angle, similar to the effect of tilt angle on sputter yield. The GaN etch rate was the highest with Cl2 and the lowest with BCl3. In the case of GaN etching with BCl3, the GaN etch rate was even lower than that in the case of GaN etched with Ar ion source only. The lower etch rate appears to be related to the higher binding energy of BCl3 and high degree of condensation on the substrate maintained at 0°C. A highly anisotropic etch profile with smooth sidewalls could be obtained with Cl2. The addition of Cl2 to BCl3 did not improve GaN etch profile. The lowest roughness value of about 10 A was obtained for the etching with Cl2. The GaN surface etched by Cl2 and BCl3 showed an N-rich surface possibly due to the removal of Ga preferentially by forming GaClx, and GaN surface etched by HCl showed near-stoichiometric surface possibly due to the removal of Ga by forming GaClx and N by forming NHx.