Characterization of Ag-x(Ge2Sb2Te5)(1-x) thin film by RF magnetron sputtering

Abstract

We reported the Ag adding effects on the crystallization behavior in Ge2Sb2Te5 film. Ag-x(Ge2Sb2Te5)(1 - x) films (where x=0-0.2) were deposited on SiO2 wafer and glass substrate by RF magnetron co-sputtering and annealed by RTA (rapid thermal annealing) at various temperature to crystallize. The effects of Ag adding on the structural, thermal and electrical properties were measured by X-ray diffraction, X-ray reflectivity, AFM, SEM, DSC and 4-point probe analysis. It was found that the crystallization temperature increased by Ag adding in Ge2Sb2Te5 films. However, the surface of Agx(Ge2Sb2Te5)(1-x) films got rough when annealing temperature and Ag contents increased. According to the Kissinger method, the activation energy for crystallization increased as the Ag content increased. It is thought that Ag atoms in Ge2Sb2Te5 act as an amorphous stabilizer and they make it hard to switch from amorphous to crystalline phase. From this study, we would show the Ag-0.06(Ge2Sb2Te5)(0.94) film is suitable for phase change memory material because of its higher crystallization temperature and structural stability. (c) 2006 Elsevier Inc. All rights reserved.