No abstract

No abstract

No abstract

No abstract

No abstract

No abstract

In this paper we analyze recent progress in Phase-Change Memory (PCM) technology targeting both Storage Class Memory and embedded applications. The challenge to achieve a high temperature data retention without compromising the device programming speed can be addressed by material engineering. We show that volume and thermal confinement improvement of the phase-change material enables a high (10-fold) reduction of the programming current, achieved also by the optimization of the device architecture, in particular in the case of a confined structure. It leads to a higher cell efficiency proven by a 6x reduction of the programming current density wrt a standard PCM structure. Furthermore, we demonstrate the reduction of thermal losses by the tuning of the thermal conductivity of the dielectrics surrounding the phase-change material. Finally, we propose some considerations about the PCM ultimate scaling and the reliability at such dimensions, showing that the engineering of the bottom electrode/phase-change material interface can lead to a reduced variability in scaled devices.

Resistive Random Access Memories (RRAMs) are a promising solution to implement Ternary Content Addressable Memories (TCAMs) that are more area-and energy-efficient with respect to Static Random Access Memory (SRAM)-based TCAMs. However, RRAM-based TCAMs are limited in the number of bits per word due to the low ratio between the resistances of the high and low resistance states (HRS/LRS) and resistance variability of RRAM. Such a limitation on the word length hinders the parallel search of a very large number of data bits for data-intensive applications. To overcome this issue, for the first time, we propose a new TCAM cell composed of two transistors and two RRAMs in a 1T2R1T configuration, where a RRAM voltage divider (2R) biases a transistor gate (1T) and an additional transistor is used to program the RRAMs (1T). A 3x128bits 1T2R1T TCAM macro were designed, integrated and extensively characterized. We experimentally demonstrate that the sensing margin of the proposed structure is insensitive to HRS/LRS RRAM resistance ratio and variability. With respect to the most common type of 2T2R RRAM-based TCAM [1-3], the proposed circuit improves the sensing margin by >5000x while reaching search times of 0.93ns. This allows the search of large volumes of data in parallel. In addition, the proposed structure improves programming and search endurance by 100x and >10x, respectively.