Study of damage reduction of (Ba-0.6,Sr-0.4)TiO3 thin films etched in Ar/CF4 plasmas

Abstract

A barium strontium titannate (BST) thin films were etched in CF4/Ar using inductively coupled plasma. The high etch rate obtained at a CF4(20%)/Ar(80%) and the etch rate in pure argon was twice as high as that in pure CF4. This indicated that BST etching is a sputter-dominated process. It is impossible to avoid plasma-induced damage by energetic particles in the plasma and the contamination of nonvolatile etch products. The plasma damage was evaluated in terms of leakage current density, residues on the etched sample, and the change in roughness. After the BST thin films were exposed in the plasma, the leakage current density and roughness increased. In addition, there are appeared a nonvolatile etch products and the x-ray diffraction (XRD) (110) and (111) intensities are decreased and broaden. After annealing at 600 degreesC in O-2 ambient for 10 min, the leakage current density, roughness, and nonvolatile etch products were reduced and the XRD (110) and (111) intensities increased. From these results, the attribution of the recovery of plasma induced damage by annealing process is owing to the desorption of metal fluorides at high temperature. (C) 2003 American Vacuum Society.