氧化鉿鋯之鋯濃度最佳化應用於三維垂直式鐵電穿隧接面元件與低溫翻轉響應之鐵電隨機存取記憶體

Abstract

由於鐵電氧化鉿鋯(Hf1-xZrxO2, HZO)材料具有極化的特性應用於非揮發性記憶體研究，此論文透過原子層沉積調控摻雜鋯的比例以研究鐵電穿隧接面元件(Ferroelectric Tunnel Junctions, FTJ)，更進一步設計三維立體垂直式FTJ，實現高密度陣列記憶體，在相同面積占比下堆疊FTJ元件，並展示其具有邏輯閘操作潛力，電流開關比達到1500倍，此外透過低溫量測來探討鐵電記憶體(FeRAM)的操作速度極限，結果顯示反鐵電電容的操作速度優於正鐵電電容，且證明部分四方晶相 (tetragonal phase)主導的反鐵氧化鉿鋯在低溫下會部分轉變成正交晶相 (orthorhombic phase) 進而導致殘餘極化量上升創造更佳的記憶存取空間，提升反鐵電電容應用在未來新興記憶體的潛力。

Due to the polarizability of ferroelectric hafnium zirconium oxide (Hf1-xZrxO2, HZO) material, it has been applied in the research of non-volatile memory. This reserch adopts atomic layer deposition to control the doping ratio of zirconium and investigates ferroelectric tunnel junctions (FTJ). Furthermore, a three-dimensional vertical FTJ design has been developed to achieve high-density array memory, allowing for the stacking of FTJ elements within the same footprint. This research demonstrates the potential for logic gate operations with a current switching ratio of> 1500x. Additionally, low-temperature measurements have been conducted to explore the operational speed limits of ferroelectric memory (FeRAM). This results show that the switching speed of anti-ferroelectric capacitors exceeds that of ferroelectric capacitors. It has been confirmed that the tetragonal phase of hafnium zirconium oxide partially transform to the orthorhombic phase at cryogenic region, resulting in increasing remnant polarization and creating improved memory access space. Thesethesis enhance the potential application of anti-ferroelectric capacitors in emerging memory technologies.