From compositional tuning to thermal budget engineering: Strategies to mitigate the wake-up effect in HZO and Al-doped HZO thin films

This paper investigates the wake-up phenomenon in ferroelectric HfₓZr₁₋ₓO₂ (HZO) thin films for non-volatile memory integration. While optimizing the Hf content (x) and film thickness can mitigate the initial pinched loop behavior, both pathways incur severe penalties in remanent polarization ( 2Pᵣ ) or coercive field ( 2Ec ). To address high-reliability demands, we evaluate aluminum-co-doped HZO (HZAO), which provides superior automotive-grade stability but inherently exacerbates the initial wake-up effect. By systematic tuning of the crystallization thermal budget, we successfully eliminate this bottleneck. While low-temperature annealing ( 400\,∘C ) results in a severely suppressed normalized polarization ratio ( RP ≈ 0.25 ), an 800\,∘C thermal budget yields wake-up-free HZAO films ( RP ≈ 0.99 ) with high 2Pᵣ values ( ~ 40~ C/cm² ). Crucially, unlike undoped HZO, which severely degrades due to leakage currents at these temperatures, the HZAO films maintain a pristine ferroelectric loop shape without any structural degradation, offering a clear pathway for immediate device utilization without extensive preconditioning.