Simultaneously achieving high-κ and strong ferroelectricity in Hf0.5Zr0.5O2 thin film by structural stacking design

The superior dielectric and ferroelectric properties of HfO 2 -based thin films, coupled with excellent silicon compatibility, position them as highly attractive candidates for dynamic and ferroelectric random-access memories (DRAM and FeRAM). However, simultaneously achieving high dielectric constant ( κ ) and strong ferroelectricity in HfO 2 -based films presents a challenge, as high- κ and ferroelectricity are associated with the tetragonal and orthorhombic phases, respectively. In this study, we report both the good ferroelectric and dielectric properties obtained in W/Hf 0.5 Zr 0.5 O 2 (HZO ∼6.5 nm)/W with morphotropic phase boundary structure by optimizing stacking sequence of HfO 2 and ZrO 2 sublayers. Notably, by alternating stacking of 1-cycle HfO 2 with 1-cycle ZrO 2 sublayers ((1–HfO 2 )/(1–ZrO 2 )), high- κ (>50) and large polarization (2 P r >40 μC/cm 2 , after wake-up) can be achieved. Besides, the (1–HfO 2 )/(1–ZrO 2 ) stacking configuration presents better thermal stability compared to other stacking sequences. Furthermore, the incorporation of an Al 2 O 3 layer leads to a low leakage current density (<10 –7 A/cm 2 at 0.65 V) and high dielectric endurance over 10 13 cycles (operating voltage ∼0.5 V). A low equivalent oxide thickness (EOT ∼0.53 nm) and considerable polarization with low leakage are simultaneously achieved. These results highlight the potential of HfO 2 -based films with optimized structural stacking as a trade-off approach for integrating DRAM and FeRAM on one-chip. • Hf 0.5 Zr 0.5 O 2 films with morphotropic phase boundary phase were designed by tuning the stacking of HfO 2 and ZrO 2 sublayers. • High dielectric constant (>50) and large remanent polarization (2 P r ∼45 μC/cm 2 , after wake-up) were achieved. • A low EOT (∼0.53 nm) and considerable polarization with low leakage were simultaneously achieved with inserting Al 2 O 3 layer.