Thermal conductivity and boundary resistance measurements of GeSbTe and electrode materials using nanosecond thermoreflectance

Phase change memory (PCM) uses rapid heating and cooling to induce switching in sub-micron memory cells. The rapid rates of heating and nanoscale dimensions require accurate modeling of thermal transport phenomena in the constituent materials. This motivates improved understanding of the thermal properties of Ge₂Sb₂Te₅ (GST) thin films and PCM electrode materials. We report measurements of thermal conductivity and interface resistance of GST and electrode materials by applying nanosecond pump-probe thermoreflectance to multilayer structures of GST-C, GST-TiN, and GST-Ti. We measure the total thermal resistance of the stack from the transient thermal response, separating the intrinsic and boundary resistance terms using a 1-D resistor model of the stack. The intrinsic conductivities for GST are 0.20 W/(m K) for GST-C, 0.33 W/(m K) for GST-TiN, 0.27 W/(m K) for low temperature deposited GST-Ti, and 0.69 for high temperature deposited GST-Ti. The thermal boundary resistances are 27.5 m²K/GW for GST-C, 5.2 m²K/GW for GST-TiN, 49.8 m²K/GW for low temperature GST-Ti, and 11.4 m²K/GW for high temperature GST-Ti.