Thermal Stability of SiO 2 Doped Ge 2 Sb 2 Te 5 for Application in Phase Change Random Access Memory

Thermal stability of Ge 2 Sb 2 Te 5 (GST) and SiO 2 doped GST (SGST) films for phase change random access memory applications was investigated by observing the change of surface roughness, layer density and composition of both films after isothermal annealing. After both GST and SGST films were annealed at 325°C for 20 min, root mean square (RMS) surface roughness of GST was increased from 1.9 to 35.9 nm but that of SGST was almost unchanged. Layer density of GST also steeply decreased from 72.48 to 68.98 g/cm 2 and composition was largely varied from Ge : Sb : Te = 22.3 : 22.1 : 55.6 to 24.2 : 22.7 : 53.1, while those of SGST were almost unchanged. It was confirmed that the addition of a small amount of SiO 2 into GST film restricted the deterioration of physical and chemical properties of GST film, resulting in the better thermal stability after isothermal annealing.

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