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

Abstract

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 10(9) 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 kappa 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.