BACKGROUND

Flash memory is a widely used type of nonvolatile memory. However, flash memory is expected to encounter scaling difficulties. Therefore, alternatives types of nonvolatile memory are being explored. Among these alternatives types of nonvolatile memory is phase change memory (PCM). PCM is a type of nonvolatile memory in which a phase of a PCM is employed to represent a unit of data. PCM has fast read and write times, non-destructive reads, and high scalability. However, the phase change layer of the PCM is easily to react with water, moisture, and halogen gas, so that the chemical stoichiometry composition ratio of the phase change layer is changed, thereby degrading the switchable performance of the phase change layer.

