Thickness dependence below 10 nm on the ferroelectric HfN 1.15 thin film formation by ECR-plasma sputtering

Abstract In this paper, the thickness dependence on the ferroelectric HfN 1.15 formed by electron cyclotron resonance-plasma sputtering was investigated. The thickness of HfN 1.15 was decreased from 10 nm to 5 nm. The equivalent oxide thickness (EOT) of 2.3 nm was obtained when the thickness of HfN 1.15 was 7 nm. As the thickness of HfN 1.15 decreased to 5 nm, the EOT slightly increased, the leakage current did not increase as we expected. The density of interface states ( D it ) was found to be as low as 1.5 × 10 11 cm −2 eV −1 even though the thickness of HfN 1.15 was decreased. As the thickness of HfN 1.15 decreased, the ferroelectric properties degraded. The positive-up negative-down measurement demonstrate that switching polarization of 9.8 μC cm −2 was achieved when the thickness of HfN 1.15 was 10 nm, while it was degraded to 2.7 μC cm −2 for 7 nm thick HfN 1.15 and no ferroelectricity was observed for 5 nm thick HfN 1.15 .