Crystallization-induced stress in thin phase change films of different thicknesses

We have studied crystallization-induced stress in phase change films (Ge₂Sb₂Te₅) as a function of thickness and with and without a capping layer, by measuring the deflection of microcantilevers. The stress is found to increase with decreasing film thickness. A thin dielectric capping layer leads to a further increase in stress compared to uncapped films. This observation can be explained by the suppression of stress relaxation in the phase change film in the presence of a capping layer. High stress will affect device performance as the size of phase change memory cells decreases.