Etching mechanism of (Ba,Sr)TiO3 films in high density Cl-2/BCl3/Ar plasma

Abstract

(Ba, Sr)TiO3 (BST) thin films have attracted great interest as new dielectric materials of capacitors for ultralarge-scale integrated dynamic random access memories such as 1 or 4 Gbit. In this study, inductively coupled BCl3/Cl-2/Ar plasmas was used to etch BST. The Cl-2/(Cl-2+Ar) was fixed at 0.2, and the BST thin films were etched by adding BCl3. The characteristics of the plasmas were estimated using optical emission spectroscopy (OES). The change of Cl, B radical density was measured by OES as a function of BCl3 percentage in Cl-2/Ar. The cross section of BST thin films and residue remaining after the etch was investigated by scanning electron microscopy. The chemical reactions between BST and Cl-2 and the surface of BST films etched with different BCl3/Cl-2/Ar gas mixing ratios were investigated using x-ray photoelectron spectroscopy. (C) 2000 American Vacuum Society. [S0734-2101(00)14504-X].