Etch characteristics of CeO2 thin films as a buffer layer for the application of ferroelectric random access memory

Cerium oxide (CeO2) thin film has been proposed as a buffer layer between t he ferroelectric film and the Si substrate in metal-ferroelectric-insulator - silicon structures for ferroelectric random access memory applications. I n this study, CeO2 thin films were etched with a Cl-2/Ar gas combination in an inductively coupled plasma. The etch properties were measured for diffe rent gas mixing ratios of Cl-2/(Cl-2 + Ar) while the other process conditio ns were fixed at rf power (600 W) dc bias voltage (-200 V), and chamber pre ssure (15 mTorr). The highest etch rate of the CeO2 thin film was 230 Angst rom /min and the selectivity of CeO2 to YMnO3 was 1.83 at a Cl-2/(Cl-2 +Ar) gas mixing ratio of 0.2. The surface reaction of the etched CeO2 thin film s was investigated using x-ray photoelectron spectroscopy (XPS) analysis. T here is a Ce-Cl bonding by chemical reaction between Ce and Cl. The results of secondary ion mass spectrometer analysis were compared with the results of XPS analysis and the Ce-Cl bonding was discovered at 176.15 (arnu). The se results confirm that the Ce atoms of the CeO2 thin films react with chlo rine and a compound such as CeCl remains on the surface of the etched CeO2 thin films. These products can be removed by Ar-ion bombardment. (C) 2001 A merican Vacuum Society.