Nonvolatile flash memory device with ferroelectric blocking layer via in situ ALD process

To improve performances of nonvolatile charge trap flash memory devices, we propose an in situ Hf_0.5Zr_0.5O₂ (HZO)/HfO₂/Al₂O₃ stacked structure, which is compatible for Si with the metal–oxide–semiconductor (MOS) process based on all atomic layer deposition. Since the appropriate bandgap difference between Al₂O₃ and HfO₂, stable charge trap operation is achieved. High-quality ferroelectric HZO film characteristics were showed by minimizing defects and Si diffusion through the sub-layer of Al₂O₃/HfO₂. Therefore, HZO as a blocking layer enhances the memory performance of the charge trap structure due to its specific polarization effect. The proposed device has the high polarization characteristics of HZO (2P_r > 20  $μ$ C/cm²) along with a MOS-cap window (>4 V), good retention capability (>10 years), fast program/erase response operation times (<200  $μs$⁠), and strong durability (>10⁵ cycles) while operating as a form of single level cell. By comparing Al₂O₃ and ferroelectric HZO as a blocking layer of the charge trap device, we confirmed that the HZO/HfO₂/Al₂O₃ multi-layer structure had excellent characteristics according to various memory performance indicators. Our proposed high-performance charge trap flash memory can be employed in various applications, including Si-based three-dimensional structures with artificial intelligence systems.