Etch characteristics of HfO2 films on Si substrates

The etch rates and mechanisms for HfO2 thin films in Cl2-, SF6- or CH4/H2-based plasmas were measured as a function of source power, r.f. chuck power and discharge composition. Both Cl2- and SF6-based plasmas produced some degree of chemical enhancement in the etch mechanism. Selectivities between 0.2 and 5 were obtained for Si over HfO2 in these two plasma chemistries. High fidelity pattern transfer was achieved for photoresist-masked HfO2/Si structures etched with Cl2/Ar over a broad range of pressures or with SF6/Ar at low pressures. The surface morphologies of both HfO2 and Si were smooth over a wide range of etching conditions.