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

(Ba, Sr)TiO3 (BST) thin films have attracted great interest as new dielectr ic materials of capacitors for ultralarge-scale integrated dynamic random a ccess 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 c hange of Cl, B radical density was measured by OES as a function of BCl3 pe rcentage in Cl-2/Ar. The cross section of BST thin films and residue remain ing after the etch was investigated by scanning electron microscopy. The ch emical reactions between BST and Cl-2 and the surface of BST films etched w ith different BCl3/Cl-2/Ar gas mixing ratios were investigated using x-ray photoelectron spectroscopy. (C) 2000 American Vacuum Society. [S0734-2101(0 0)14504-X].