Ferroelectricity Improvement in Ultra‐Thin Hf0.5Zr0.5O2 Capacitors by the Insertion of a Ti Interfacial Layer

Abstract

The effect at the nanoscale of a Ti interfacial layer on the performances of TiN/HfZrO/TiN capacitors is reported. Ferroelectric hafnium zirconium oxide (HZO) is synthesized by magnetron sputtering of a ceramic target. Titanium nitride top and bottom electrodes are grown by reactive magnetron sputtering. The insertion of an ultra‐thin Ti layer at the top electrode/HZO interface impacts the crystalline phase and the electrical properties of the ferroelectric HZO. Following post‐deposition annealing, the Ti layer is oxidized and becomes titanium oxide. Compositional and structural characterization is performed using glancing incidence X‐Ray diffraction and electron energy‐loss spectroscopy. The TiOz layer is clearly distinguishable at the top electrode/HZO interface. Electrical characterization is conducted by positive‐up‐negative‐down (PUND) technique. The remnant polarization reaches a maximum value of for 6 nm thick HZO. The results are discussed in the framework of structural, compositional, and physical properties of the electrode/HZO interfaces and their effect on the electrical performances of thin HZO‐based junctions, which could subsequently be considered for the demonstration of synaptic learning mechanisms for neuromorphic applications.