Modeling and Simulations of the Integrated Device of Phase Change Memory and Ovonic Threshold Switch Selector With a Confined Structure

We present a finite-element model for the confined-structure device integrating a phase change memory (PCM) and an ovonic threshold switch (OTS) selector. In this model, the threshold switching (TS) characteristics of the PCM and OTS were described by an embedded numerical model to simulate the operation of the integrated device. Both the SET and RESET processes have been well implemented in the integrated device by simulating. The electronic properties of the integrated device with various OTS material parameters have been investigated by simulating. Based on the simulated results, a moderate set-pulse has been obtained by optimizing only the OTS conductivity at a high-conductivity state. Further simulations for multilevel storage have been carried out in the integrated device based on the optimized OTS. The results indicate the confined-structure device with a larger length-diameter ratio will result in a more flexible operation window for multilevel storage. Particularly, when the length-diameter ratio of the confined-structure is 2:1 in the integrated device, five levels of device resistance could be obtained in the simulations of multilevel storage by applying multiple set-pulse or reset-pulse. This could guide further studies on the multilevel storage.