Capacitive Memory Window With Non-Destructive Read in Ferroelectric Capacitors

Abstract

Energy-efficient memory elements having a non-volatile memory window (MW) with a non-destructive read operation are highly desirable for both random access memory and compute-in-memory applications. In this work, we demonstrate a record high non-volatile capacitive MW and non-destructive read in hafnium zirconate-based metal-ferroelectric-metal capacitors (FeCAPs). Firstly, we show that a non-zero capacitive MW at zero read voltage can be realized by engineering an asymmetry between the top and bottom ferroelectric-metal interfaces and demonstrate a record high MW of ~4.71×ϵ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> at 0 V. Secondly, we show that the capacitive MW can be further improved by optimizing a non-zero read voltage. This allows to achieve a record high MW of ~7.5×ϵ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> for the asymmetric FeCAP, and even opens up a MW as high as ~8.0×ϵ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> for the symmetric FeCAP. Finally, we demonstrate that the MW can be reliably read non-destructively as long as the read voltage is carefully selected to avoid partial or full polarization switching during the read operation.