Combination-Encoding Content-Addressable Memory Utilizing the Ferroelectric Hf-Zr-O Field-Effect-Transistor Array

Abstract

We fabricated an Hf-Zr-O (HZO) ferroelectric field-effect transistor (FeFET) array as a combination-encoding content-addressable memory (CECAM), offering higher content density than other ternary content-addressable memories (TCAM). Considering the robust nonvolatile memory behavior of FeFETs and efficient parallel searching ability through combination-encoding, the CECAM fabricated with the HZO FeFET array is a suitable candidate for next-generation searching engines. Additionally, it offers advantages such as negligible standby power, optimal matching, high content density, and significantly reduced operation power (mismatch power). The average mismatch power per bit per switch in CECAM significantly decreased with increasing size, with reductions of up to 65% for CECAMs containing more than eight FeFETs compared to TCAMs using the same FeFETs. We developed a calculation model to estimate CECAM matching current and power consumption based on the characteristics of a single FeFET, enabling performance prediction from early research stages and facilitating CECAM circuit design.