Polarization degradation and recovery strategies of hafnia-based ferroelectric capacitors after thermal budget in Back-End of Line process

In this work, addressing the key issue of polarization degradation of hafnia-based ferroelectric (FE) memory units after Back-End of Line (BEOL) process, we reveal a close correlation between remnant polarization (Pr) loss and alterations in oxygen levels, proposing strategies for recovery. The main findings are: (1) Oxygen migration into hafnia-based capacitors (FeCAPs) during Furnace treatment introduces domain pinning, which diminishes Pr value and decelerates switching speed; (2) The recovery strategy of ultra-high vacuum re-annealing to extract oxygen from hafnia-film through electrode layer is proposed and demonstrated for the first time; (3) Low-temperature re-annealing (350℃) in ultrahigh vacuum (10^-2 Pa) with sufficient time (30 min) can make the Pr of FeCAPs recover up to 112%. These results provide insights into the mechanisms underlying thermal degradation and restorability, contributing to the advancement of hafnia-based memory technologies.