Ferroelectric phenomena in Si-doped HfO₂ thin films with TiN and Ir electrodes

Ferroelectric HfO₂ is an attractive candidate for future ferroelectric random access memory devices due to its compatibility with the complementary metal-oxide-semiconductor process, conformal deposition, and scaling ability. Crystallization of HfO₂ with different dopants and annealing conditions can produce the stabilization of the monoclinic, tetragonal, cubic, or orthorhombic crystal phases. In this work, the authors observe ferroelectric behavior in Si-doped hafnium oxide with TiN and Ir electrodes. Atomic layer deposited 10 nm HfO₂ capacitors doped with varying concentrations of SiO₂ have been fabricated in the metal-ferroelectric-insulator-semiconductor (MFIS) structure. The ferroelectric characteristics of thin film HfO₂ are compared in the MFIS and metal-ferroelectric-metal configurations. Post-metallization anneals were applied to all thin film ferroelectric HfO₂ capacitors, resulting in a remanent polarization of up to 22 μC/cm² and a range of observed coercive voltages, emphasizing the importance of the annealing conditions, electrode materials, and device structure on the ferroelectric properties of thin film HfO₂.