Enhanced memory window of ferroelectric Hf0.5Zr0.5O2 by NH3 treatment

Abstract

Hf0.5Zr0.5O2 based capacitors with a metal–ferroelectric–metal structure have been fabricated in this study, with or without ammonia plasma nitridation at the metal/oxide interfaces. The purpose of this work is to study the role nitrogen plays in the ferroelectric properties of these materials. It is observed that ferroelectricity is enhanced after the interface treatment with NH3 plasma nitridation. The material analysis results indicate that this ferroelectricity improvement results from the diffusion of nitrogen atoms into the Hf0.5Zr0.5O2 film at the metal/oxide interface. Further, the nitrogen binds to the oxygen vacancies at the interface and forms a nitrogen-doped Hf0.5Zr0.5O2 film, enabling oxygen vacancies movement. After 90 s of NH3 plasma interfacial treatment, the metal–ferroelectric–metal capacitor device achieves a maximum memory window of 3.7 V. The results of the electrical test and physical phase analysis demonstrate that NH3 plasma interfacial treatment of ferroelectric thin films can effectively improve the interfacial effect between ferroelectric materials and the top electrode, which in turn enhances the storage performance of the device.