摘要
Ba 0.5 Sr 0.5 TiO 3 (BST) thin films were patterned for fabricating BST capacitors in a helicon-wave plasma system. The optimization conditions were an Ar (80%)/Cl 2 (20%) gas mixture with a helicon-wave plasma power and a substrate bias rf power of 1500 and 90 W, respectively. From results of X-ray photoelectron spectroscopy, physical ion bombardment is more effective than chemical reaction for removing Sr, while Ti can be removed by the formation of volatile TiCl x . Ba was primarily removed by chemically assisted physical etching (such as that using BaCl x ). Some etching residues consisting of Ba and Sr were found after the BST films were etched and increased leakage current density. Oxygen surface plasma treatment can effectively repair surface damage caused by etching, and it reduced the leakage current density of the BST capacitor from 4.0 × 10 -7 to 3.0 × 10 -8 A/cm 2 at 1 MV/cm and increased the breakdown field to ∼2MV/cm at 1.0 × 10 -16 A/cm 2 . © 2006 The Japan Society of Applied Physics.