鐵電電容式記憶體特性及研究

Abstract

鐵電材料是一種具有雙穩態特性的材料，在電場的作用下能夠產生持久的極化狀態，也能夠在無外部電場的情況下保持所極化的狀態，並即在不同的極化狀態之間切換。這種特性使得鐵電材料成為理想的記憶體元件，可以實現高密度、非揮發性的數據存儲，使其廣泛應用於記憶體中。本研究選擇摻雜不同鋯濃度的氧化鉿鋯(Hf1-xZrxO2, HZO)作為鐵電材料，並對其特性進行了深入研究和應用。鐵電電容式記憶體（Ferroelectric Capacitive Memory, FCM）主要分為累積式FCM和反轉式FCM，同時都有低功耗、快速的寫入速度、長時間保持性和耐久度等優點，並應用於類神經運算。通過TCAD模擬的結果，觀察到反轉型FCM施加負偏壓時，n+摻雜區產生帶對帶穿隧效應。製作不同鐵電層濃度和結構的FCM元件，結果顯示MPB( Morphotropic Phase Boundary) SL(superlattice)-HZO具有較高的開關比，並且在保持度和耐久度量測中表現出更優異的性能，具有對稱性| αp - αd | = 0.03 ~ 0.35的深度學習操作，展現成為類神經突觸元件的能力。Ferroelectric materials are kind of material with exhibited bi-stable state, where they can generate a persistent polarization state under the influence of an electric field and retain the polarization state even in the absence of an external field, allowing for switching between different polarization states. This unique property makes ferroelectric materials ideal for memory devices, enabling high-density and non-volatile data storage, leading to their widespread application in memory technology. In this study, HZO (Hf1-xZrxO2, HZO) doped with varying zirconium concentrations was selected as the ferroelectric material, and its characteristics were thoroughly investigated and applied.Ferroelectric Capacitive Memory (FCM) is primarily categorized into accumulation-mode FCM and inversion-mode FCM, both offering advantages such as low power consumption, fast write speed, long-term data retention, and durability, and finding applications in neuromorphic computing. Through TCAD simulation results, it was observed that the inversion-mode FCM exhibits band-to-band tunneling effects in the n+ doped region under negative bias. Fabrication of FCM devices with different ferroelectric layer concentrations and structures revealed that MPB (Morphotropic Phase Boundary) SL (superlattice)-HZO demonstrated a higher switching ratio and exhibited superior performance in terms of retention and endurance measurements.