Thermal stability of GeSbTe thin films deposited by layer-by-layer metalorganic chemical vapor deposition

The thermal stability of the GeSbTe (GST) films deposited by layer-by-layer metalorganic chemical vapor deposition on the planar Ti Al N ∕ Si and on trenches 120 nm in diameter and 500 nm deep (with aspect ratio of 4:1) was investigated under various annealing temperatures and durations in a nitrogen ambient atmosphere. The inhomogeneous distribution of the Ge and Sb elements in the as-grown GST layer was improved by a thermal treatment at 500 ° C for 60 min in nitrogen ambient. The GST films annealed above 500 ° C for 30 and 60 min were delaminated from the TiAlN electrode. Samples annealed at 700 ° C for 1 min , above the melting temperature of the GST, show a decreased thickness, indicating that the GST films were thermally unstable. The as-grown films on trenches did not show a complete fill of the structure, whereas the trenches were more fully filled after a thermal treatment at 500 ° C for 60 min .