Towards the understanding of ferroelectric-intrinsic variability and reliability issues on MCAM

Abstract

The advent of hafnia-based ferroelectric field-effect transistors (FeFETs) prompted the evolution of data-intensive applications, such as multi-bit content addressable memories (MCAMs). Though the identification of FeFET variation sources and the understanding of FeFET retention problems have been discussed in existing literature, the impact of these issues on the FeFET -based MCAM is still not uncovered. Herein, we carried out the investigation on the variability and reliability issues of the FeFET -based MCAM. The threshold voltage ($V_{th}$) variation due to nonuniform ferro electricity results in the long-tailed distribution of delay, thereby limiting the expansion of the MCAM array. The $V_{th}$ shift during retention leads to the accuracy decline, which is more prominent after endurance cycling. Further optimization is required for the MCAM arrays to achieve more accurate and efficient search operation.