Chapters authored
Optimization of the Phase Change Random Access Memory Employing Phase Change Materials
Phase-change random access memory (PCRAM) is a semiconductor device based on phase change material (PCM). The SET speed is the bottleneck of limiting the speed of PCRAM. Extract the electrical parameters of the SET operation of the PCRAM test chip and analyze the process of the SET operations. It is found that adding a high and narrow pulse before a single pulse (SP) benefits the SET resistance reduction and the SET speed improvement. A dual pulses SET (D-SET) method is proposed and optimized. The mechanism of D-SET is that the first pulse forms a large optimum temperature field cover over all regions of the PCM material. When the first pulse is converted to the second pulse, the optimum temperature field shrinks and causes the amorphous regions to rapidly crystallize from the edge to the center. On the 40 nm PCRAM test chip, the SET time of D-SET method is under 300 ns. Compared with the conventional SET method such as SP and staircase down pulses (SCD), the D-SET method is optimal for SET performance such as SET resistance distribution, SET speed, and the anti-drift ability.
Part of the book: Phase Change Materials and Their Applications