Endurance Enhancement of Elevated-Confined Phase Change Random Access Memory

Abstract

Phase change random access memory (PCRAM) is the most promising candidate for the next-generation nonvolatile memory. Recently, elevated-confined PCRAM using an elevated metal column was proposed as a promising approach to achieve lower RESET current. This paper studied the writing strategy to enhance the endurance of elevated-confined PCRAM through both experiment and simulation. Elevated-confined PCRAM incorporating Ge2Sb2Te5 were fabricated and tested. The overwriting test showed that the failure mode of elevated-confined PCRAM was stuck SET. As diffusion, which is the main reason for stuck SET, is highly dependent on working temperature, writing strategies are investigated to minimize the over-heating in elevated-confined PCRAM. From the simulation results, it is found that RESET pulse width is more effective than RESET pulse amplitude in controlling of over-heating. The testing results showed that the endurance cycles can be improved from 106 to 108 with shorter and lower RESET pulse, which is consisted with simulation results.