High-performance Pt/SrBi₂Ta₂O₉/HfO₂/Si structure for nondestructive readout memory

Metal-ferroelectric-insulator-semiconductor (MFIS) capacitors with 390-nm-thick SrBi₂Ta₂O₉ (SBT) ferroelectric film and 8-nm-thick hafnium oxide (HfO₂) layer on silicon substrate have been fabricated and characterized. It is demonstrated for the first time that the MFIS stack exhibits a large memory window of around 1.08 V at an operation voltage of 3.5 V. Moreover, the MFIS memory structure suffers only 18% degradation in the memory window after 10⁹ switching cycles. The excellent performance is attributed to the formation of well-crystallized SBT perovskite thin film on top of the HfO₂ buffer layer, as evidenced by the distinctive sharp peaks in X-ray diffraction (XRD) spectra. In addition to its relatively high κ value, HfO₂ also serves as a good seed layer for SBT crystallization, making the proposed Pt/SrBi₂Ta₂O₉/HfO₂/Si structure ideally suitable for low-voltage and high-performance ferroelectric memories.