Thermal budget study to simultaneously achieve low-temperature (<400 °C) process and high endurance of ferroelectric Hf_0.5Zr_0.5O₂ thin films

This work comprehensively investigates the thermal budget required to simultaneously achieve low-temperature process conditions and high endurance in atomic layer deposited ferroelectric Hf_0.5Zr_0.5O₂ (HZO) thin films. Because a certain level of thermal budget is required to achieve ferroelectricity in 10 nm HZO thin films, the crystallization temperature can be lowered below 400 °C by simply increasing the annealing time. In addition, the analysis of the crystallization behavior of HZO thin films based on the Johnson-Mehl-Avrami-Kolmogorov model revealed that longer annealing times are required to lower the annealing temperature for HZO crystallization due to the limitation of the crystallization rate. Consequently, low-temperature (<400 °C) ferroelectric HZO thin films with large remanent polarization along with improved leakage behavior and endurance were realized. These results not only facilitate the back-end-of-line integration of HZO thin films but also demonstrate the feasibility of in situ HZO crystallization by thermal budget for subsequent interconnect formation, simplifying the overall process and saving costs by eliminating a dedicated annealing process.