Ferroelectric Hf1-xZrxO2 memories: device reliability and depolarization fields

The influence of depolarization and its role in causing data retention failure in ferroelectric memories is investigated. Ferroelectric Hf
_0.5
Zr
_0.5
O
₂
thin films 8 nm thick incorporated into a metal-ferroelectric-metal capacitor are fabricated and characterized with varying thicknesses of an Al
₂
O
₃
interfacial layer. The magnitude of the depolarization field is adjusted by controlling the thickness of the Al
₂
O
₃
layer. The initial polarization and the change in polarization with electric field cycling is strongly impacted by the insertion of Al
₂
O
₃
within the device stack. Transient polarization loss is shown to get worse with larger depolarization fields and data retention is evaluated up to 85 ° C.