Stress Reduction of Ge2Sb2Te5 by Inhibiting Oxygen Diffusion

The unique solution to the stress reduction of Ge2Sb2Te5 phase-change material has been known to cap a layer with an inherently huge compressive stress. In this paper, another approach to the stress reduction is firstly presented in view of the compositional change of Ge2Sb2Te5, particularly due to oxygen diffusion. During thermal cycles, we measured the radius changes using four kinds of samples and calculated their stress-changes using Stoney equation. In case of basic specimen, more oxygen in GeSb2Te5 and larger stress-change are observed as cycling temperature increases. In the rest of samples, the stress-change is reduced compared with the basic one, only when a capping layer on Ge2Sb2Te5 blocks the oxygen penetration effectively. The stress increase by the oxygen diffusion is considered to be due to the lattice distortion of Ge2Sb2TC5. [doi:10.2320/matertrans.MRA2008042]