Phase change memory (PCM) is an important element in the development and realization of new forms of brain-like computing. In this article, a three-dimensional finite element method simulation is carried out to study the temperature profiles within PCM cells for a better understanding of switching operations. On the basis of a finite difference method, the simulation consists of phase transition kinetics, electrical, thermal, percolation effect, as well as thermoelectric effects, using temperature-dependent material parameters. The Thomson effect within the phase-change material and the Peltier effect at the electrode contact are respectively considered for a detailed analysis of the impact on the temperature profiles and the programming current for switching processes. The simulation results show that switching operations are primarily implemented by the melting and quenching of the phase-change material close to the contact between the bottom electrode and phase change material, and its final phase distribution is determined by the cooling rate. With positive current polarity, thermoelectric effects improve heating efficiency and then reduce the programming current. Because of the different occurrence region, the Peltier effect significantly changes the temperature profile, which is more influential in switching operations. Additionally, the contribution of thermoelectric effects decreases with the cell size scaling because of the weakening of the Peltier effect. This paper aims at providing a more precise description of the thermoelectric phenomena taking place in switching operations for future PCM design.

The scaling effect on the thermoelectric heating process in phase-change memory (PCM) cells is computationally investigated through a three-dimensional finite-element simulation of the reset operation on Ge ₂ Sb ₂ Te ₅ (GST) mushroom cells. Both isotropic and non-isotropic scaling are considered. Thomson heat within GST and Peltier heat at the electrode-GST interface are separately analyzed through the captured thermal profiles within PCM cells. The results of this study indicated that the influence of Peltier heat became weaker with the cell size decreasing mainly due to a larger heat loss via the electrodes, and the steeper thermal gradients within the GST layer sustained the contribution of Thomson heat. The thermoelectric heat can be enhanced by modifying the Seebeck coefficient and the thermal conductivity of materials. Our model provides useful insights of the impact of cell scaling on thermoelectric effects, which are critical parts of effective cell engineering.