Comparative Study of Reliability of Ferroelectric and Anti-Ferroelectric Memories

With the discovery of the ferroelectric (FE) properties within HfO2, the scaling gap between state-of-the-art technology nodes and non-volatile memories based on FE materials can be bridged. In addition to non-volatility, new memory concepts should guarantee sufficient endurance and operation stability. However, in contrast to optimized perovskite based FEs, binary oxide based FE memories still show changes in the memory window (MW) followed by either hard breakdown or closure of the MW. Recently, we have shown that anti-FE (AFE) materials exhibit very stable and significantly higher endurance with respect to the FE counterparts. Inspired by the robustness and remarkable cycling performance of the AFE materials, we analyze the remaining reliability aspects of these devices. By characterizing the pure film properties of capacitor stacks and switching performance when integrated into devices, we compare and investigate temperature stability, imprint, retention, and variability of both FE and AFE memories. We investigate if the lower energetic barrier to be overcome together with partial switching and lower switching induced stress are responsible for the higher endurance of the AFE with respect to the FE based memories. By utilizing charge trapping and charge pumping tests together with leakage current spectroscopy in combination with comprehensive modeling we check that assumption. Moreover, we identify the interfacial buffer layer as the weakest link of these devices.