First Demonstration of Vertical 2T-nC FeRAM Hybrid Cell and Its Scalability for High-Density 3D Ferroelectric Capacitor Memory

In this work, we perform a comprehensive experimental and modeling study into the scaling of vertical 2T-nC ferroelectric random-access memory (FeRAM) hybrid cell to demonstrate a high performance and high-density 3D capacitor memory. We demonstrate: i) first time successful integration of the vertical 2T-3C FeRAM cell by stacking the vertical metal-ferroelectric-metal (MFM) stack on top of Si CMOS transistors; ii) successful experimental operation of the memory cell, including the quasi-nondestructive read out (QNRO) of the polarization without write back after 10⁶ read cycles; iii) the write bit line (WBL) heavily screens the coupling between neighboring strings, making it a minor concern; v) aggressive stacking of the WBLs, i.e., number of MFMs in a string, could facilitate the self-boosting during write operation due to ferroelectric linear capacitance (CFE), which allows self-boosted inhibition for VW/2 scheme and worsens the VW/3 scheme as disturb increases to intolerable 2VW/3; v) aggressive horizontal scaling significantly increases the read disturb to cells on neighboring planes due to capacitance between two WBLs (CZ).