Reduced Leakage and Enhanced Endurance via an ITO Oxygen Reservoir Layer in HZO Ferroelectric Capacitors

This work proposes a simple, BEOL compatible strategy to improve endurance of Hf0.5Zr0.5O2(HZO) ferroelectric capacitors by inserting indium tin oxide (ITO), a conductive metal oxide as a passivation interlayer. Without electrode replacement, ITO interlayer serves as an oxygen reservoir at the interface between the top tungsten (W) electrode and HZO. By tailoring the O2flow of 0.5 sccm (Oxygen-Poor) and 2 sccm (Oxygen-Rich) during ITO sputter deposition, the W/ITO/HZO/W capacitors exhibit more than 250x enhanced endurance, sustaining nearly 109switching cycles, without sacrificing the remanent polarization compared to the ITO-free W/HZO/W capacitors. X-ray Photoelectron Spectroscopy (XPS) reveals oxygen vacancy (VO) compensation at the top interface, confirming the oxygen-reservoir role of the ITO interlayer. Furthermore, by analyzing leakage current and dead-layer formation of the capacitors with ITO deposited in different oxygen flow rate, we outline a strategy for enhancing the reliability of hafnium-based ferroelectric devices.