Enhanced Capacitive Memory Window by Improving Remnant Polarization in Ferroelectric Capacitors for Non-Destructive Read

The unique concept of a non-volatile capacitive memory window (CMW) in ferroelectric (FE) capacitors (FeCAP) allows for a non-destructive read operation (NDRO). NDRO decouples the read- from the write-endurance which is ideal for random access memory and compute-in-memory applications. However, the optimal strategy to further improve the CMW remains uncertain. In this work, we first identify potential pathways to improve the CMW by studying the dependence of the relative dielectric permittivity (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\epsilon _{\text {r}}$ </tex-math></inline-formula>) of a FE on the remnant polarization (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${P}_{\text {R}}$ </tex-math></inline-formula>) and coercive field (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${E} _{\text {C}}$ </tex-math></inline-formula>). Results show that a FE stack having a higher <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${P}_{\text {R}}$ </tex-math></inline-formula> and/or a lower <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${E}_{\text {C}}$ </tex-math></inline-formula> leads to an improved <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\epsilon _{\text {r}}$ </tex-math></inline-formula> and CMW for a given read-bias. Next, we experimentally demonstrate this and show that a trilayer FeCAP with an enhanced <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2{P}_{\text {R}}$ </tex-math></inline-formula> achieves a high CMW<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$_{\epsilon }$ </tex-math></inline-formula> of ~20, which is ~1.5x higher than earlier best. Finally, we demonstrate a pulse-based NDRO confirming a robust 1.5x enhancement in CMW even after <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$10^{{11}}$ </tex-math></inline-formula> NDRO cycles.