Low Damage and Anisotropic Dry Etching of High-k Dielectric HfO2 Films in Inductively Coupled Plasmas

The etch characteristics of high-k dielectric HfO2 films and the etch selectivity for HfO2 over Si in fluorine-and chlorine-based inductively coupled plasmas have been studied. Fluorine-based ICP discharges produced practical and controllable etch rates and the etched HfO2 surfaces sustained similar or better RMS roughness values than that of the unetched control sample under most of the conditions examined. Anisotropic pattern transfer with a vertical sidewall profile (theta = 97 degrees) was performed in CF4/Ar ICP discharges and no significant change in the dielectric property of HfO2 films was detected. 5Cl(2)/10O(2) ICP discharges produced high etch selectivities > 6.3 (max. similar to 7.6) for HfO2 over Si.