Carbon-Based Liner for RESET Current Reduction in Self-Heating Phase- Change Memory Cells

The use of carbon-based (C-based) liners is investigated for RESET current reduction in self-heating, pillar-shaped phase-change memory (PCM) cells for storage class memory (SCM) technologies. The liner is inserted between the top electrode and the phase-change layer. A finite element analysis (FEA) is done to simulate the effect of this liner on the RESET current, using the melting current as a proxy. From this FEA, we see that the high resistance of the C-based liner increases the heat generation at the interface with the phase-change layer, changing the cell from being solely self-heated by the phase-change layer to a combination of the phase-change layer's self-heating and heating from the C-based liner. The simulation results are validated against experimental results from fabricated pillar cells. We show the liner reduces the melting current of the pillar cell by 60%. The effect of the thickness of the C-based liner and the phase-change layer on the melting current is quantified, showing a strong dependence on the liner thickness and a weak dependence on the phase-change layer thickness. These findings can guide the design of PCM cells with high-resistance liners between the electrode and phase-change layer for RESET current reduction.

I. Introduction

Phase-change memory (PCM) has been investigated as a nonvolatile memory for decades. These ongoing developments have recently brought it to the level of a viable storage class memory (SCM) [1], a type of memory that offers faster access times than the NAND flash memory and lower cost than the dynamic random-access memory (DRAM) technology. The main merits of PCM are its scalability, reliability, endurance, and even the possibility of multilevel storage.