Ferroelectric capacitors with triple level cell storage capability at low operating voltage by introducing TiN interlayer

Abstract

Inserting an ultrathin TiN interlayer into a ferroelectric HfZrOx (HZO) film of 10 nm by in situ ALD was proposed to implement ferroelectric capacitors (FeCAPs) in this work. The FeCAPs with the structure of TiN/HZO/TiN/HZO/TiN show a high remanent polarization (2Pr) of 32.6 μC/cm2 at a low operating voltage of 2 V and a pulse width of 5 μs. Compared to those without TiN interlayer, this work shows Pr enhancement by 2.2× under partial-switching conditions (2 V/5 μs) and 50% reduction of operating voltage to achieve comparable Pr under full-switching. This work also demonstrates the triple-level cell (TLC, 3 bits/cell) storage capability and can achieve robust endurance up to 3 × 107 cycles under partial-switching endurance conditions (±2 V/5 μs) when combined with the recovery method. The promising properties are mainly attributed to the high ratio of the orthorhombic phase of the HZO film. These results attest to the eligibility of the TiN interlayer to implement low-power, high-reliability, and high-density FeCAPs for embedded memory applications.