Back-end-of-line-compatible low-voltage operation in Hf0.5 Zr0.5O2 ferroelectric film enabled by in-situ lanthanum doping

ABSTRACT HfO2-based ferroelectric devices have attracted substantial attention in non-volatile memories due to their sub-3 nm scalability and robust ferroelectric properties. However, challenges such as double remanent polarization (2Pr) degradation and high thermal budget have hindered their integration as advanced technology nodes. Here, we developed an in-situ lanthanum doping strategy in ferroelectric capacitors to address these issues. By controlling the atomic layer deposition pulses of La2O3, HfO2 and ZrO2, the lanthanum-doped HZO (La: HZO) film with different lanthanum concentrations were prepared. An ultra-low thermal budget below 300°C was demonstrated in the 0.44% La: HZO film, while maintaining a pronounced 2Pr of 27.8 μC/cm2. First-principles calculations suggest that lanthanum incorporation promotes the formation of oxygen vacancies, which is believed to stabilize the orthorhombic phase and activate ferroelectricity in the La: HZO films. Furthermore, the back-end-of-line compatible capacitor with La: HZO also exhibits a low operating voltage of 2.0 V, excellent ferroelectricity with 2Pr of 37.5 μC/cm2, rapid switching speed of 446 ns, record-high breakdown voltage of 5.73 V, superior endurance properties over 1011 cycles and substantial retention. These results provide new insights for the design of non-volatile memories with low power consumption and high operating speed.