Electrothermal Investigation on Vertically Aligned Single-Walled Carbon Nanotube Contacted Phase-Change Memory Array for 3-D ICs

Electrothermal investigation on vertically aligned single-walled carbon nanotube (SWCNT) contacted phase-change memory (PCM) array is performed using the 3-D time-domain finite-element method. The in-house-developed algorithm is verified by comparing the simulated results with the experimental ones published by others. Thermal coupling between adjacent cells, which may cause current leakage and reliability degradation, is characterized for PCMs with different geometrical parameters, which could be caused by fabrication variation. It is shown that spacing variation between adjacent PCM cells draws a slight effect on their thermal coupling. However, thermal boundary resistance of the phase-change material-oxide interface and SWCNT diameter affect temperature rise and thermal coupling significantly. On the other hand, it is indicated that the SWCNT contacted PCM has microampere-scale programming current and nanosecond-scale thermal response time, which make it vulnerable to electrostatic discharge (ESD). Electrothermal responses to ESD are captured and compared, which show that unintentional ESD can change the state of PCM and result in error programming.