High Density Dry Etching of (Ba,Sr)TiO3 and LaNiO3

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 (≤ 100 Å-min−1) under all conditions, the Cl2/Ar produced a smooth anisotropic pattern transfer. The etching was still strongly ion-assisted, but maximum removal rates of ∼900 Å min−1 for both materials were achieved with selectivities of ∼16 for BST and ∼7 for LNO over Si. A single layer of thick (∼7 μm) photoresist is an effective mask under these conditions.