Tunable Defect Engineering of Mo/TiON Electrode in Angstrom-Laminated HfO$_2$/ZrO$_2$ Ferroelectric Capacitors towards Long Endurance and High Temperature Retention

Abstract

A novel defect control approach based on laminated HfO$_2$/ZrO$_2$ with multifunctional TiN/Mo/TiOxNy electrode is proposed to significantly improve the endurance and data retention in HZO-based ferroelectric capacitor. The O-rich interface reduces leakage current and prolong the endurance up to 1011 cycles while retaining a 2Pr value of 34 ($\mu$C/cm$^2$ ) at 3.4MV/cm. Using first-principles calculations and experiments, we demonstrate that the enhancement of endurance is ascribed to the higher migration barrier of oxygen vacancies within the laminated HZO film and higher work function of MoO$_x$/TiO$_x$N$_y$ between top electrode and the insulating oxide. This 2.5-nm-thick TiOxNy barrier further increase the grain size of HZO, lowering the activation field and thus improving polarization reversal speed. This interfacial layer further decreases the overall capacitance, increases the depolarization field, thereby enhancing the data retention. By fitting the data using the Arrhenius equation, we demonstrate a 10-year data retention is achieved at 109.6 $^\circ$C, surpassing traditional SS-HZO of 78.2 $^\circ$C with a 450$^\circ$C RTA (required by backend-of-the-line). This work elucidates that interfacial engineering serves as a crucial technology capable of resolving the endurance, storage capability, and high-temperature data retention issues for ferroelectric memory.