Investigation of TiO2 seed layer engineering for improved remanent polarization uniformity, TDDB reliability, and dipole switching in La-doped ferroelectric HZO MFM devices

Abstract

This study investigates the impact of a TiO₂ seed layer on the reliability and dipole switching uniformity of La-doped Hf₀.₅Zr₀.₅O₂ (La:HZO) metal–ferroelectric–metal (MFM) capacitors. The introduction of the TiO₂ seed layer promotes a higher fraction of the (002)-oriented orthorhombic phase, resulting in improved dipole alignment and enhanced remanent polarization (2Pr) uniformity. Time-dependent dielectric breakdown (TDDB) analysis under constant voltage stress (CVS) reveals that, although the mean breakdown time of both samples is comparable, the TiO₂-seeded device exhibits a significantly higher Weibull β value, indicating improved breakdown uniformity and a higher predicted 10-year safe operating field. Furthermore, the Nucleation-Limited Switching (NLS) model was employed to extract the dipole switching time constant (τ₀) and activation field (Eₐ) distributions. The TiO₂-seeded sample (Sample B) shows a narrower τ₀ and Eₐ distribution, corresponding to more uniform dipole switching dynamics, whereas the non-seeded sample (Sample A) exhibits faster but more dispersed switching behavior. These results confirm that the TiO₂ seed layer enhances both ferroelectric phase orientation and switching uniformity, leading to improved reliability and 2Pr performance of La:HZO-based ferroelectric devices.