Electrical Properties of Metal-Ferroelectric-Insulator-Semiconductor (MFIS)- and Metal-Ferroelectric-Metal-Insulator-Semiconductor (MFMIS)-FETs Using Ferroelectric SrBi2Ta2O9Film and SrTa2O6/SiON Buffer Layer

Nonvolatile memory operations of p-channel metal-ferroelctric-insulator-semiconductor (MFIS)- and metal-ferroelectric-metal-insulator-semiconductor (MFMIS)-FETs using ferroelectric SrBi2Ta2O9(SBT) film and SrTa2O6(STA)/SiON stacked buffer layer have been demonstrated. It is determinded that the Al/STA/SiON/Si structure with a SiO2equivalent thickness of 3.7 nm has low leakage current of 10-8A/cm2. The memory window of 1.1 V is obtained for Pt/SBT/STA/SiON MFIS-FETs, whereas Pt/SBT/Pt/STA/SiON/Si MFMIS-FETs have memory windows as large as 3.0 V when the area ratio SM/SFis 3.8 or 5.9. Furthermore, it is also demonstrated that by reducing the metal-ferroelectric-metal (MFM) capacitor area, significant improvement of data retention characteristics can be achieved. The drain current on-off ratio remains at more than three orders of magnitude even after an elapse of 10 h.