Fabrication and characterization of sub-0.6-µm ferroelectric-gate field-effect transistors

Sub-micron-gate Pt/SrBi2Ta2O9/Hf-Al-O/Si ferroelectric-gate field-effect transistors (FeFETs) were successfully fabricated using electron-beam lithography, metal hard mask technique and dry etching. Scanning electron microscopy measurements revealed that the gate length of a fabricated FeFET was 0.56 ?m. Drain current versus gate voltage curves showed steep switching and a memory window of 0.93 V when the applied gate voltage range was 1 ? 5 V. Excellent endurance characteristics were observed up to 108 program/erase cycles, indicating that the FeFETs are suitable for use in NAND flash memory applications. Retention measurements showed that the drain current ON/OFF ratio (104) did not undergo any significant change up to 105 s.