Multiple Polarization States in Hf 1− x Zr x O 2 Thin Films by Ferroelectric and Antiferroelectric Coupling

Abstract HfO 2 ‐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 Hf 1− x Zr x O 2 ( x = 0.65 to 0.75) thin films grown through sequential atomic layer deposition (ALD) of HfO 2 and ZrO 2 exhibiting three‐step domain switching characteristic in the form of triple‐peak coercive electric field ( E C ) distribution. This long‐sought behavior shows nearly no changes even at up to 125 °C and after 1 × 10 8 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 E C 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 Hf 1− x Zr x O 2 capacitors with excellent device‐to‐device variation and long data retention, by the full switching of individual peaks in the triple‐peak E C . The work represents a significant step in implementing reliable non‐volatile multi‐state ferroelectric devices.