Impact of Doped Hafnium Oxides on Memory Window and Low-Frequency Noise in Ferroelectric FETs

In this article, we have studied the impact of different doped hafnium oxides (X:HfO2) in ferroelectric field-effect transistors (FeFETs) based on 28-nm high-K metal gate (HKMG) and 12-nm fully depleted silicon-on-insulator (FDSOI) technology. The introduction of different elements through appropriate doping enables the stabilization of a higher symmetrical phase in HfO2 (cubic, tetragonal) and the final transition to the orthorhombic phase, which is the origin of ferroelectricity. The required concentration for this stabilization is different for different dopants, which in turn results in different ferroelectric parameters such as coercive electric field (
${E}_{c}$
) and remnant polarization (
${P}_{r}$
). These parameters impact the memory window and trap densities at or near the SiO2/X:HfO2 interface. The density-functional theory (DFT) calculations using the first-principle method also verify the above. The carriers’ trapping/de-trapping results in a change in the threshold voltage and endurance issues. A DFT and TCAD-based study has shown the reliability aspects of ferroelectric transistors due to different HfO2-dopants, which is necessary for ferroelectric material optimization for low-voltage logic and memory applications.