The etching mechanism of (Ba,Sr)TiO3 films using Cl-2/Ar inductively coupled plasma

(Ba,Sr)TiO3 thin film is a suitable material for the application in high de nsity dynamic random access memories (DRAMs) because of the high relative d ielectric constant and small variation in dielectric properties with freque ncy. An anisotropic etching of BST thin films is very important in ferroele ctric devices to support a small feature size and pattern transfer. In this study, BST thin films were etched with Cl-2/Ar inductively coupled plasma (ICP). The etching characteristic of BST films was studied as a function of Cl-2/(Cl-2+Ar). BST films etched with different Cl-2/Ar gas mixing ratio w ere investigated using x-ray photoelectron spectroscopy (XPS) and secondary ion mass spectrometer (SIMS). The surface reaction of the etched (Ba,Sr)Ti O3 thin films was investigated with XPS. Pa is removed by chemical reaction such as BaCl2 and physical sputtering. Ar ion bombardment is more effectiv e than chemical reaction between Sr and Cl to remove Sr. Ti is easily remov ed by chemical reaction such as TiCl4. The result of SIMS analysis compared with the results of XPS analysis were the same.