Evolution of Materials and Device Stacks for HfO 2 ‐Based Ferroelectric Memories

ABSTRACT The discovery of ferroelectricity in HfO 2 offering the advantage of nonvolatile polarization switching creates a renewed interest in the semiconductor memory industry. Doped HfO 2 ‐based thin films maintain stable remanent polarization (P r ) at nanometer‐scale thicknesses within back‐end‐of‐line thermal budgets, which makes them an attractive material family for compact ferroelectric capacitors (FeCAPs) and ferroelectric field‐effect transistors (FeFETs) in embedded and in‐memory computing. The orientation of electric dipoles in the HfO 2 layer defines the stored information in FeCAPs and adjusts the electron density in the channel of FeFETs. Therefore, controlling dipole rotation, which is closely linked to P r , plays an important role in achieving reliable memory operation. In this review, we first show the evolution of doped HfO 2 thin films in terms of engineering the ferroelectric orthorhombic phase. Since the ferroelectric HfO 2 layer is deposited onto non‐inert metal electrodes in FeCAPs or semiconductor materials serving as a channel in FeFETs, the reliability characteristics of the ferroelectric memories primarily depend on these interface conditions. Therefore, we second address recent interface engineering strategies tailored to each device configuration.