Polar Axis Orientation Control of Hafnium-Based Ferroelectric Capacitors with in-Situ AC Electric Bias During Rapid Thermal Annealing

Hafnium-based ferroelectric (FE) thin films, prepared via atomic layer deposition (ALD), suffered from random oriented polar axis (PA), posing challenges and complexities for device scaling and variation. To effectively control the PA orientation and enhance polarization, we employed in-situ AC electric bias (E) during rapid thermal annealing (RTA) treatment (i.e. RTA+E). The main findings are: (1) Direct experimental evidence of variable orthogonal (0-) PA has been obtained for the first time, originating from tetragonal (T-) to O- transition in RTA cooling; (2) Applying E during cooling significantly enhances polarization in hafnium-based FE capacitors up to ~121.6% increase; (3) The RTA+E method effectively controls the O-PA orientation towards the out-of-plane E direction. These findings solidly demonstrate that the PA orientation of O-grain can be controlled in fluorite-type FE thin films.