Post metallization annealing effect utilizing Pt gate electrode for MFSFET with ferroelectric nondoped HfO₂ formed by Ar/O₂-plasma sputtering

Abstract

In this paper, we investigated the effect of post metallization annealing (PMA) to improve the device characteristics of metal-ferroelectrics-Si field-effect transistor (MFSFET) with ferroelectric nondoped HfO₂ formed by the Ar/O₂-plasma reactive sputtering. The remnant polarization (2P_r) of 2.5 μC/cm² was obtained for the MFS diodes with 20 nm thick HfO₂ and 1 nm thick Hf interlayer followed by the PMA of 600 °C/30 s in N₂ ambient, while it was 2.3 μC/cm² for the sample with post deposition annealing (PDA). The memory window (MW) of 0.4 V was obtained in the C–V characteristics in case of the PMA process, while it was 0.22 V in case of the PDA process. This is because the orthorhombic phase formation was enhanced by the PMA process compared to the PDA process. It was found that the small coercive field (E_c) of 0.52 MV/cm was obtained by the PMA process. Furthermore, the memory window (MW) of 0.15 V was realized under the program/erase (P/E) pulses width of 100 ns with P/E voltages of − 5.5 V and 6.5 V, respectively.