Oxygen Concentration Effect on Conductive Bridge Random Access Memory of InWZnO Thin Film

• Main Authors: Chih-Chieh Hsu, Po-Tsun Liu, Kai-Jhih Gan, Dun-Bao Ruan, Simon M. Sze
• Format: Article
• Language: English
• Published: MDPI AG 2021-08-01
• Series: Nanomaterials
• Subjects: conductive-bridge RAM (CBRAM); InWZnO; bilayer switching layer; endurance cycle; defect distribution
• Online Access: https://www.mdpi.com/2079-4991/11/9/2204

In this study, the influence of oxygen concentration in InWZnO (IWZO), which was used as the switching layer of conductive bridge random access memory, (CBRAM) is investigated. With different oxygen flow during the sputtering process, the IWZO film can be fabricated with different oxygen concentrations and different oxygen vacancy distribution. In addition, the electrical characteristics of CBRAM device with different oxygen concentration are compared and further analyzed with an atomic force microscope and X-ray photoelectron spectrum. Furthermore, a stacking structure with different bilayer switching is also systematically discussed. Compared with an interchange stacking layer and other single layer memory, the CBRAM with specific stacking sequence of bilayer oxygen-poor/-rich IWZO (IWZOx/IWZOy, x < y) exhibits more stable distribution of a resistance state and also better endurance (more than 3 × 10⁴ cycles). Meanwhile, the memory window of IWZOx/IWZOy can even be maintained over 10⁴ s at 85 °C. Those improvements can be attributed to the oxygen vacancy distribution in switching layers, which may create a suitable environment for the conductive filament formation or rupture. Therefore, it is believed that the specific stacking bilayer IWZO CBRAM might further pave the way for emerging memory applications.