Boolean Logic Function Realized by Phase-Change Blade Type Random Access Memory

Abstract

Phase-change random access memory (PCRAM) has been considered as one of the most promising candidates for future nonvolatile storage applications. Recent advent of the blade-type PCRAM further shed a light on its commercial prospect due to its much smaller energy consumption than the conventional Lance-type PCRAM. However, the logic computing capability of the blade-type PCRAM remains vague up-to-date. To deeply study its function versatility, we developed a comprehensive three-dimensional model based on the classical nucleation-growth theory to mimic the crystallization and amorphization processes of the blade-type PCRAM device. According to this well-established model, the device resistance after phase transformation was calculated with respect to different crystallization and amorphization pulses. By pertaining high and low pulse magnitudes and device resistances to appropriate input and output logic levels, a variety of Boolean logic functions, including “ NAND,” NOR,” AND,” OR,” and “ NOT,” were successfully achieved on one single PCRAM cell. The feasibility of simultaneously realizing storage and logic computing functions on the designed PCRAM device was therefore demonstrated. Such intriguing merit, combined with its superb storage traits, makes the proposed blade-type PCRAM cell suitable for current in-memory computing and neuromorphic circuits as the key components of future digital computers operated on non-von Neumann mode.