Phase-change Random Access Memory (PRAM) is a key candidate for future storage-class memory in computer systems with fast switching speed, high reliability, and good scalability. The system bottlenecks have arisen due to the speed difference between information processing logic and conventional charge-based memory. In order to optimize such a hierarchical memory system, a research on the nonvolatile memory (NVM) is necessary. The basic working principle of phase change memory is a phase transition between an amorphous (high resistance, RESET state) and a crystalline (low resistance, SET state). These different resistance states are used as logic “0” and “1” to store information in the PRAM device. So far, the most widely used material in PRAM is the Ge-Sb-Te (GST) compound, which has been preceded by many studies. However, its limitations resistive drift in amorphous state and high operating power of GST materials remain major obstacles for PCM application. To solve these problems, several groups studied on nano-scale bottom heater and superlattice structure that alternately stacked different phase change materials
We have investigated a heterostructure PRAM using the dichalcogenide confined material (CM) on resistance barrier to address the resistance drift and endurance failure problems in PRAM cycling operations, and fabricated nano-scale bottom heater to reduce power consumption.