Characterization of phase-change layer thermal properties using a micro-thermal stage

Recent progress using a micro-thermal stage (MTS) allowed the control the temperature of microstructures with sub-μs time scales. This approach was applied to phase-change memory (PCM) cells to measure thermal material and device properties. In this work, we use the change in MTS thermal resistance to predict changes in the thermal conductivity or thickness of the nearby phase-change layer (PCL). More generally, we show that the MTS can be placed in-situ of a complicated system to measure the thermal properties of a single changing layer. Electrical measurements of the MTS are performed on several different structures with different PCL thicknesses including 35, 70, and 100 nm thick Ge₂Sb₂Te₅ (GST) films, a different phase-change material, and no PCL. Simulations establish the expected relationship between the MTS temperature for different input PCL thermal properties. The simulation approach is then scaled to match the experimental data and predicts the temperature in the PCL for different PCL thermal properties. Additionally, an analytical thermal circuit model is developed to describe the thermal profile of the system. The calibrated simulation and analytical models are thus able to determine thermal properties of the buried PCL by making purely electrical measurements of the MTS.