Downsizing and memory array integration of Pt/SrBi2Ta2O9/Hf-Al-O/Si ferroelectric-gate field-effect transistors

First, fabrication and characterization of a NAND flash memory using novel memory cells of ferroelectric-gate field-effect transistors (FeFETs), which is named Fe-NAND, was reviewed. A 64 kb Fe-NAND memory cell array with bit-line- and block- selector circuits was produced and characterized. Several standard operations for a NAND flash memory were demonstrated. All-cell-erase, all-cell-program, and a checkerboard-pattern program showed a good “1” vs. “0” separation in their threshold-voltage distributions. Downsizing of the memory-cell FeFETs has been also progressed. The FeFET with the gate-length 0.26 μm showed high endurance by 10⁹ cycles of 1±5 V-high and 10 μs-wide pulses imposed. Second, we also discussed our FeFET performance in comparison with the other HfO₂-based nonvolatile FETs.