Ferroelectric random-access memory (FeRAM) and ferroelectric field effect transistors (FeFET) have garnered a lot of attention as emerging next generation memory applications. Ferroelectric properties of HZO thin films have been found to be ideal candidates for such applications as they allow for reduction in the operating voltages of transistors along with low thermal budget. Ferroelectricity in hafnia-based dielectric is attributed to the presence of non-centrosymmetric orthorhombic phase (Pca21).

This paper presents important information on the effect of TiN electrodes sandwiching the HZO layer on the formation and preservation of the orthorhombic phase and their ferroelectric nature. The influence of the processing conditions of TiN electrodes such as deposition temperature, post-deposition annealing, substrate changes, influence of forming gas (FG) on the ferroelectric nature of HZO are investigated here.

The introduction provides the reader with a context of their study with adequate literature reviews. The research question is addressed by studying the crystal structure by GIXRD, stress by studying the changes in radius of curvature and ferroelectric polarization by electrical characterization. Samples underwent rapid thermal annealing at 400C done before and after top electrode deposition, with and without annealing step for the bottom electrode and FG annealing were appropriately studied here. The experiment methodology is reliable, valid and details provided suffice to replicate the experiments. It was found that the TiN electrode increases oxygen vacancies at the interface by oxygen scavenging during the HZO film deposition by ALD. The increases oxygen vacancies helped in formation of the ferroelectric phase in HZO. These results strongly impact the field in understanding the structure-ferroelectricity correlation in HZO for emerging memory applications.