Effect of Y2O3 interlayer on the electric properties of Y-doped HfO2 film deposited by chemical solution deposition

Ferroelectric oxide becomes the focus of memory industry again after the discovery of ferroelectricity in doped-HfO₂ polycrystalline films. Thermal stress is an important factor for the variation of ferroelectric phase content. In this paper, the effect of film stress induced by Y₂O₃ interlayer in the ferroelectric properties of Y-doped HfO₂ (Y: HfO₂) ferroelectric films, which is deposited by chemical solution deposition (CSD), is investigated systematically by polarization-voltage measurement. Compared with Y-doped HfO₂ film without interlayer, 1 nm Y₂O₃ interlayer enhances the remanent polarization of Y: HfO₂ film due to the effects of film stress and surface energy. And thick Y₂O₃ interlayer benefits to reduce leakage current density. But polarization switching of HfO₂ film is restrained due to the capacitor voltage divider caused by thick Y₂O₃ interlayer. The obvious enhance effect of Y₂O₃ interlayer still exists in Y: HfO₂ film at high voltage due to the breakdown of Y₂O₃ interlayer, realizing a huge remanent polarization (P_r) of 22.8 μC/cm² in Y: HfO₂ film (doping content: 4 at %). It is 3.6 times than that of ferroelectric doped-HfO₂ film without Y₂O₃ interlayer.