The effect of stress on HfO2-based ferroelectric thin films: A review of recent advances

HfO (2)-based thin films have raised considerable interest in ferroelectric memory devices due to their thickness scalability and process compatibility with CMOS. Stress exhibits a significant influence on ferroelectric polarization in HfO (2)-based films. However, the effect of stress has yet to be clarified despite numerous efforts, and there has been a lack of systematic review to collate and discuss this effect. This paper briefly introduces how stress is characterized in HfO 2-based polycrystalline films as basis. Then, the process in which stress affects ferroelectricity is carefully discussed. The paper subsequently elaborates both the effects of out of plane stress and in plane stress. Furthermore, the interaction between stress and other factors is presented. Finally, the up-to-date research on the effect of stress are summarized, and several further research challenges for researchers are provided. Given the ubiquitous stress during the chip manufacturing process, a detailed summary of the stress effect has technological implications for processing and applications of HfO 2-based thin films.