GeTe phase change material and Ti based electrode: Study of thermal stability and adhesion

Phase change memories use a specific phase change material (PCMat) as a resistor element for information storage. To obtain good reliability and performances of the device, interface between PCMat and electrodes needs to be optimized. In this work, we study the adhesion between the electrode material and GeTe PCMat by a mechanical characterization (four-point bending). Our results show that a thin titanium interfacial layer drastically enhances the adhesion energy. Using X-Ray Diffraction and Secondary Ion Mass Spectroscopy, strong chemical interactions between titanium and tellurium is evidenced. In particular, after a 400^oC anneal, Ti"3Te"4 formation is observed. This chemical affinity probably explains the improvement of adhesion between the electrode and GeTe.