Impact of Series-Connected Ferroelectric Capacitor in HfO-Based Ferroelectric Field-Effect Transistors for Memory Application

In this work, we demonstrated a HfO2-based ferroelectric field-effect transistor (FeFET) in series with a HfAlO ferroelectric capacitor for memory application and further investigated the impact of the ferroelectric capacitor with different thicknesses and areas. It was revealed that the memory window of the FeFET has a significant correlation with the ferroelectric capacitor from the transfer curves of the transistor after the series connection. By decreasing the thickness and area of the ferroelectric capacitor, the memory window of the FeFET was improved, which could be verified through the TCAD simulation tool and capacitance matching model. With the series-connected ferroelectric capacitor, in addition to optimizing the characteristics of ferroelectric memory, we can effectively avoid the interface-caused undesirable effects in conventional ferroelectric memory during film stacking. These results provide a solution for future low-power embedded memory application.