Unresolved conditions for stabilizing the ferroelectric phase in HfO2/ZrO2 thin films

Identify and rigorously characterize the remaining boundary conditions required to stabilize the ferroelectric phase in hafnium oxide and zirconia thin films at the nanoscale under integrated-circuit-compatible fabrication processes (e.g., ALD/CVD/PVD), including how these conditions affect phase purity and the absence of non-ferroelectric dead layers.

Background

Ferroelectric materials are attractive for nonvolatile memory and neuromorphic devices due to field-driven switching and potential for low write energy. The discovery of ferroelectricity in HfO2 and ZrO2 enabled compatibility with semiconductor processing flows, yet reliability and phase stability challenges persist at nanoscale dimensions.

In Section 5.3.3, the authors note that although progress has been made in understanding the boundary conditions for stabilizing the ferroelectric phase, several aspects remain unresolved. These include the precise process windows that yield a high fraction of the ferroelectric orthorhombic phase without dead layers or parasitic phases, which are crucial for achieving stable polarization and device performance.