Dry etching of BaSrTiO3 and LaNiO3 thin films in inductively coupled plasmas

High density plasma etching of (Ba,Sr)TiO3 (BST) and LaNiO3 (LNO) thin films was performed in two different plasma chemistries, Cl2/Ar and CH4/H2/Ar. While the latter chemistry produced extremely low etch rates (less than or equal to 10 nm/min) under all conditions, the Cl2/Ar produced smooth anisotropic pattern transfer. The etching was still strongly ion-assisted, but maximum removal rates of about 90 nm/min for both materials were achieved with selectivities of about 16 for BST and about 7 for LNO over Si. A single layer of thick (about 7 micron) photoresist is an effective mask under these conditions. 22 refs.