Impact of Nitrogen Plasma Treatment on the Tin Bottom Electrode and Ferroelectric Properties of Tin/Hf0.5zr0.5o2/Tin Capacitors

Abstract

This study systematically investigates the impact of nitrogen incorporation in atomic layer deposited (ALD) TiN bottom electrodes on TiOxNy interfacial layer formation and its influence on the phase composition and ferroelectric properties of 8 nm-thick Hf0.5Zr0.5O2 (HZO) films. By varying N2 plasma flow (50, 75, 100 sccm) while maintaining a fixed TiN top electrode in a TiN/HZO/TiN capacitor, we examined structural and electrical characteristics using GIXRD, AES, and HRTEM. A lower nitrogen content (50 sccm) led to increased TiOxNy formation at the HZO/TiN interface, promoting the ferroelectric orthorhombic phase and enhancing ferroelectricity but at the cost of higher leakage, lower relative permittivity (εr), and degraded endurance. Conversely, a higher nitrogen content (100 sccm) suppressed TiOxNy formation, stabilizing the tetragonal phase, which reduced ferroelectricity but improved leakage current, coercive field (EC), and endurance. The optimal balance was achieved at 75 sccm, yielding a high remnant polarization (2Pr) of 45.1 µC/cm2, low EC of 1.44 MV/cm, high εr of 29.2, and excellent endurance. These findings underscore the crucial role of nitrogen incorporation in optimizing interface quality and enhancing HZO-based capacitor performance, offering valuable insights for next-generation ferroelectric memory and logic devices.

Keywords: Hf0.5Zr0.5O2 (HZO), atomic layer deposited (ALD), TiN bottom electrode, TiOxNy interfacial layer