Enabling Energy-Efficient and High-Density eDRAM-LUT-Based Computing-in-Memory Using Anti-Ferroelectric Transistors

This paper reports a novel energy-efficient and high-memory/compute-density eDRAM Computing-in-Memory (CiM) by introducing AFEFET-based eDRAM cells into look-up tables (LUTs). The highlights include: (1) Fabricated 1-transistor-1AFEFET (1T1AF) eDRAM cell with short Amorphous-Indium-Gallium-Zinc-Oxide (<tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$a$</tex>-IGZO) channel length of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathbf{2 5 ~ n m}$</tex> and high cell density; (2) Measured high endurance over <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$2 \times 10^{9}$</tex> cycles for AFEFETs and long retention time over <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$10^{3} \mathrm{s}$</tex> for 1T1AF eDRAM cell; (3) Proposed computation mode combining digital LUT and analog capacitor coupling for the first time, enabling high energy efficiency, high compute density, and high accuracy. Evaluation results show that the proposed 1T1AF eDRAM-LUT-based CiM achieves a high memory density of 5.52 Mb/mm<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup>, a high 8 b peak compute density of 11.3 TOPS/mm<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup>, and a high 8 b peak energy efficiency of 107.2 TOPS/W, showing great potential for energy-efficient and high-performance CiM designs.