Ar/N₂ Gas Flow Rate Dependence on the Ferroelectric HfNₓ Thin Film Formation by ECR-Plasma Sputtering

In this paper, the Ar/N2 gas flow rate dependence on the ferroelectric HfNx (x>1) formed by electron cyclotron resonance (ECR)-plasma sputtering was investigated. The equivalent oxide thickness (EOT) of 2.7 nm was obtained with Ar/N2 gas flow rate of 8/7 sccm followed by the 400°C/5 min post metallization annealing (PMA) in N2. The EOT was increased to 4.2 nm with the deposition of the Ar/N2 gas flow rate of 14/16 sccm. The density of interface states (Dit) was found to be as low as $2.0\times 10{^{{11}}}$ ${\mathrm {cm}}^{-2}$ ${\mathrm {eV}}^{-1}$ . The P-V results demonstrate that a remanent polarization (2Pr) of $6.6~\mu $ C/cm2, and positive-up negative-down measurement showed the switching polarization of $4.7~\mu $ C/cm2 at an Ar/N2 flow rate of 8/7 sccm, which is high enough for metal-ferroelectric-Si field-effect transistor (MFSFET) application.