Low Bias Dry Etching of III-Nitrides in Cl↓(2)-Based Inductively Coupled Plasmas

摘要

C1↓(2)-based inductively coupled plasmas (ICP) with low additional dc self-biases (-100V) produce convenient etch rates (500-1500(A)·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 and surface morphology has been performed. The general trends are to go through a maximum in etch rate with percent C1↓(2) in the discharge for all three mixtures, and to have an increase (decrease) in etch rate with source power (pressure). Since the etching is strongly ion-assisted, aniso-tropic pattern transfer is readily achieved. Maximum etch selectivities of approximately six for InN over the other nitrides were obtained.