Experimental Investigation of Thermal Annealing and Ferroelectric Capacitor Area Effects for Hafnium-Zirconium Oxide Devices

Abstract

In this study, we reveal that the thermal budget of post-metal annealing not only determines the formation of the ferroelectric phase and dipole domain but also the film quality of the gate stack in a metal-ferroelectric-metal capacitor. The higher leakage current caused by defect traps or grain boundaries within a gate stack would influence the stability of the ferroelectric domain switching. Furthermore, the ferroelectric domain switching and polarization current also depend on the ferroelectric capacitor area. We observe that a HfAlO ferroelectric capacitor can dominate the transfer characteristics of a p-type SnO thin-film transistor through the modulation of series capacitance in the gate stack based on a one-transistor one-capacitor series configuration. According to experimental results, the memory hysteresis window can be improved significantly with the area scaling due to the improvement of capacitance matching accuracy.