Ten-Nanometer Ferroelectric $\hbox {Si:HfO}_{2}$ Films for Next-Generation FRAM Capacitors

Ferroelectric properties of Si-doped HfO₂ thin films (10 nm) have been investigated. The focus of this letter is to evaluate the potential applicability of these thin films for future 3-D ferroelectric random access memory capacitors. Polarization switching was tested at elevated temperatures up to 185°C and showed no severe degradation. Domain switching dynamics were electrically characterized with pulse-switching tests and were not in accordance with Kolmogorov-Avrami-type switching. Nucleation-limited switching is proposed to be applicable for these new types of ferroelectric thin films. Furthermore, same-state and opposite-state retention tests were performed at 125°C up to 20 h. It was found that samples that had previously been annealed at 800°C showed improved retention of the written state as well as of the opposite state. In addition, fatigue measurements were carried out, and no degradation occurred for 10⁶ programming and erase cycles at 3 V.