Wake-up-free properties and high fatigue resistance of HfxZr1-xO2-based metal-ferroelectric-semiconductor using top ZrO2 nucleation layer at low thermal budget (300 degrees C)

Ferroelectricity and crystallinity of TiN/ZrO2/HfxZr1-xO2 (Hf:Zr = 0.43:0.57; HZO)/SiO2/Si metal-ferroelectric-semiconductor (MFS) capacitors with a top ZrO2 nucleation layer fabricated by low-temperature processes at 300 degrees C of atomic layer deposition and post-metallization annealing (PMA) were systematically investigated. The HZO (10 nm)-based MFS capacitors without (w/o) and with 2- and 10-nm-thick ZrO2 films (ZrO2-2 nm and ZrO2-10 nm, respectively) were found to form an extremely thin SiO2 interfacial layer (SiO2-IL) with a thickness of one or two monolayers. The HZO film in the TiN/ZrO2/HZO/SiO2/Si capacitors formed the ferroelectric orthorhombic phase even with a low thermal budget of 300 degrees C; in contrast, that of the w/o capacitor exhibited a predominantly amorphous structure. This result is attributed to the polycrystalline ZrO2 film acting as a nucleation layer for the crystallization of an amorphous HZO film during PMA treatment. Therefore, the remnant polarization (2P(r)) increased in the order of w/o (2.2 mu C/cm(2)) < ZrO2-2 nm (6.8 mu C/cm(2)) < ZrO2-10 nm (15 mu C/cm(2)). The endurance properties of the ZrO2-10 nm capacitor were free from the wake-up effect and exhibited less degradation because of the insertion of a thick ZrO2 film of 10 nm at the TiN/HZO interface, which promoted the preferential formation of the ferroelectric orthorhombic phase and prevented the formation of oxygen vacancies at the ZrO2/HZO interface. These results suggest that superior ferroelectricity with wake-up-free properties and higher fatigue resistance of HZO-based MFS capacitors can be achieved by a low-temperature fabrication technique (300 degrees C) using a top ZrO2 nucleation layer. (C) 2022 Author(s).