Multiple Polarization States in Hf1−xZrxO2 Thin Films by Ferroelectric and Antiferroelectric Coupling

Abstract

HfO2‐based multi‐bit ferroelectric memory combines non‐volatility, speed, and energy efficiency, rendering it a promising technology for massive data storage and processing. However, some challenges remain, notably polarization variation, high operation voltage, and poor endurance performance. Here we show Hf1−xZrxO2 (x = 0.65 to 0.75) thin films grown through sequential atomic layer deposition (ALD) of HfO2 and ZrO2 exhibiting three‐step domain switching characteristic in the form of triple‐peak coercive electric field (EC) distribution. This long‐sought behavior shows nearly no changes even at up to 125 °C and after 1 × 108 electric field cycling. By combining the electrical characterizations and integrated differential phase‐contrast scanning transmission electron microscopy (iDPC‐STEM), we reveal that the triple‐peak EC distribution is driven by the coupling of ferroelectric switching and reversible antiferroelectric–ferroelectric transition. We further demonstrate the 3‐bit per cell operation of the Hf1−xZrxO2 capacitors with excellent device‐to‐device variation and long data retention, by the full switching of individual peaks in the triple‐peak EC. The work represents a significant step in implementing reliable non‐volatile multi‐state ferroelectric devices.