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 $$\text {Hf}_{x}\text {Zr}_{1-x}\text {O}_{2}$$ (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 ( $$2P_{\text {r}}$$ ) or coercive field ( $$2E_{\text {c}}$$ ). 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 ( $$400\,^{\circ }\text {C}$$ ) results in a severely suppressed normalized polarization ratio ( $$R_{\text {P}} \approx 0.25$$ ), an $$800\,^{\circ }\text {C}$$ thermal budget yields wake-up-free HZAO films ( $$R_{\text {P}} \approx 0.99$$ ) with high $$2P_{\text {r}}$$ values ( $$\sim 40~\upmu \text {C/cm}^2$$ ). 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.