LOW-BIAS DRY-ETCHING OF III-NITRIDES IN CL-2-BASED INDUCTIVELY-COUPLED PLASMAS

Cl-2-based inductively coupled plasmas (ICP) with low additional de se lf-biases (-100V) produce convenient etch rates (500-1500 Angstrom.min (-1)) for III-nitride electronic device structures. A systematic study of the effects of additive gas (Ar, N-2, H-2), discharge composition, process pressure, and ICP source power and chuck power on etch rate a nd surface morphology has been performed. The general trends are to go through a maximum in etch rate with percent Cl-2 in the discharge for all three mixtures, and to have an increase (decrease) in etch rate w ith source power (pressure). Since the etching is strongly ion-assiste d, anisotropic pattern transfer is readily achieved. Maximum etch sele ctivities of approximately six for InN over the other nitrides were ob tained.