Memory Window and Endurance Improvement of HfZrO-Based FeFETs with ZrO Seed Layers Characterized by Fast Voltage Pulse Measurements.

The HfO-based ferroelectric field effect transistor (FeFET) with a metal/ferroelectric/insulator/semiconductor (MFIS) gate stack is currently being considered as a possible candidate for high-density and fast write speed non-volatile memory. Although the retention performance of the HfO-based FeFET with a MFIS gate stack could satisfy the requirements for practical applications, its memory window (MW) and reliability with respect to endurance should be further improved. This work investigates the advantage of employing ZrO seed layers on the MW, retention, and endurance of the HfZrO (HZO)-based FeFETs with MFIS gate stacks, by using fast voltage pulse measurements. It is found that the HZO-based FeFET with a ZrO seed layer shows a larger initial and 10-year extrapolated MW, as well as improved endurance performance compared with the HZO-based FeFET without the ZrO seed layer. The results indicate that employing of a direct crystalline high-k/Si gate stack would further improve the MW and reliability of the HfO-based FeFETs.