Narrowing coercive field distribution in HfO2 ferroelectric memory via oxygen vacancy modulation for low-voltage operation

Abstract

Low-voltage hafnia-based ferroelectric memory is essential but remains challenging because conventional strategies, such as thickness scaling or mean coercive field reduction, often incur leakage or remanent polarization (Pr) penalties. A key but often overlooked factor is that EC is not a single value but exhibits a broad domain-to-domain distribution, whose high-field tail typically determines the voltage required for full polarization switching. Here, we show that narrowing the standard deviation (σ) rather than merely lowering its mean (μ) enables low-voltage switching in Hf0.5Zr0.5O2 capacitors without the usual trade-off in leakage or Pr. This is achieved by tailoring the oxygen dose during atomic layer deposition in a trilayer stack, which compensates for the spatial inhomogeneity of oxygen vacancy and thereby reshapes the local switching landscape. A low operating voltage of 1.5 V is achieved in 10 nm devices with 2Pr of 44 μC/cm2 and a leakage current density of 5 × 10−6 A/cm2. The same strategy remains effective at 6 nm, where an operating voltage of 0.9 V maintains 2Pr above 40 μC/cm2. These results establish a new paradigm for realizing low-voltage HfO2-based FeRAM compatible with advanced logic nodes by engineering σ of the EC distribution.