Temperature-and Frequency-Dependent Ferroelectric Characteristics of Metal-Ferroelectric-Metal Capacitors with Atomic-Layer-Deposited Undoped HfO2 Films

Abstract

In this study, we evaluated the temperature-and frequency-dependent ferroelectric characteristics of TiN/undoped HfO2/TiN metal-ferroelectric-metal (MFM) capacitors in which an undoped HfO2 film was deposited through atomic layer deposition (ALD). Successful ferroelectric characteristics were achieved after postdeposition annealing at 650◦ C, which exhibited a remanent polarization of 8 µC/cm2 and a coercive electric field of 1.6 MV/cm at 25◦ C (room temperature). The ferroelectric property was maintained at 200◦ C and decreased as the temperature increased. The ferroelectric property was completely lost above 320◦ C and fully recovered after cooling. The frequency depen-dency was evaluated by bias-dependent capacitance–voltage and s-parameter measurements, which indicated that the ferroelectric property was maintained up to several hundred MHz. This study reveals the ultimate limitations of the application of an undoped HfO2 MFM capacitor.