Novel hafnium oxide (HfO2)-based ferroelectrics reveal full scalability and complementary metal oxide semiconductor integratability compared to perovskite-based ferroelectrics that are currently used in nonvolatile ferroelectric random access memories (FeRAMs) and ferroelectric field effect transistor. Within the lifetime of the device, two main regimes of wake up and fatigue can be identified which was inferred the root cause is domain de-pining/pining effect attributed to oxygen vacancies in HfO2-based dielectric. The evolution of unstable polarization may strike the electrical performance within the reliability test for future device applications.
The main scope of this study is to eliminate wake up and fatigue effect during electric field cycling by surface NH3 plasma treatment which is performed on different position. The endurance of PDP sample which was applied NH3 plasma between both top/bottom electrode and ferroelectric material interfaces with cycling up to #106 is stable which were verified by electrical analysis I-V curve, P-V curve, leakage current and C-V curve, i.e. wake up and fatigue cannot be observed in PDP sample. With NH3-plasma treatment, the XPS analysis reveals that about 7% oxygen vacancies can be reduced. Besides, the XRD diffraction pattern shows a noncentral-symmetric orthorhombic phase in NH3-plasma treatment sample, which was inferred as the proof of ferroelectric crystallized phase in hafnium-based oxide, furthermore, TEM images reveals an interfacial TiOxNy at the bottom and ferroelectric material for STD sample which without plasma treatment while no such layer is found for PDP sample which confirms that N-rich TiN is efficient to block electrode and ferroelectric material reaction.

由於微縮技術以及與金屬氧化物半導體整合的相容性高，以二氧化鉿為基底之新穎的鐵電材料近期時常被應用於鐵電非揮發性記憶體（FeRAM）或是電晶體上。在鐵電材料元件的操作上，會隨著操作次數增加而有兩種效應會隨之發生：Wake up 以及Fatigue效應，這兩種效應與鐵電材料的鐵電域是否因為氧空缺數量多而被釘札住有密切的關係，然而此兩種效應會造成往後元件在操作上的表現產生不穩定性。
此實驗中，我們在鐵電層不同的位置進行NH3 電漿之處理，並觀察鐵電材料的電性以及物性特性，其中以在上/下電極與鐵電層之介面皆以NH3 電漿處理之樣品（PDP樣品）容忍度特性表現改善最為顯著，當操作到#106¬次數時不論是從I-V特性、P-V特性、漏電流以及C-V特性圖皆可以發現隨著操作次數的增加其特性穩定性高，也就是成功地消除Wake up 以及Fatigue效應。另外，XRD顯示樣品在經由NH3電漿處理後亦可產生非對稱性之orthorhombic的結晶性;XPS顯示，經由NH3電漿處理後的樣品其鐵電層內氧空缺可減少約7%與電性特性沒有Wake up 以及Fatigue效應相互呼應;TEM顯示在沒有做任何電漿處理的樣品有一層不完全鍵結的氧化層TiOxNy，然而在上/下電極與鐵電層之介面皆以NH3 電漿處理的樣品沒有此氧化層，此結果可以證實在介面進行NH3電漿處理確實可以抑制電極與鐵電層之反應。

Abstact........................................................................................................................................i
摘要…........................................................................................................................................ii
Contents....................................................................................................................................iii
List of Illustration....................................................................................................................vi
List of Table………………………………………………………………………….….…..xi

Chapter 1 Introduction.............................................................................................................1
1-1 Background...........................................................................................................................1
1-1-1 Polarization........................................................................................................1
1-1-2 Ferroelectric Properties.....................................................................................2
1-1-3 Hafnium Dioxide………………………………………………………..…….5
1-2 Applications of Ferroelectric materials…............................................................................7
1-2-1 Ferroelectric Random Access Memory (FeRAM)……………………………7
1-2-2 Ferroelectric Field Effect Transistor (FeFET)…………………………….8
1-2-3 Ferroelectric Tunnel Junction (FTJ)…………………..……………………9
1-3 Motivation to study Zr doped HfO2 material………………………………………………9

Chapter 2 Literature Review….............................................................................................20
2-1 Ferroelectricity of Hafnium Oxide Thin Film....................................................................20
2-2 Incipient Ferroelectricity in Zr-doped HfO2 Thin Films....................................................21
2-3 Correlation between Oxide Vacancies and Wake up/Fatigue Effect in Ferroelectric Materials....................................................................................................................................21
2-4 Formation of Oxygen Vacancies…………………………………………...….…………23
2-5 Conclusion & Motivation……………………………………………………………...…24

Chapter 3 Experiment Process……………………………………………………………..32
TiN/HfZrO2/TiN MIM Capacitor Fabrication..........................................................................32

Chapter 4 Results & Discussions………………………...…………………………………39
4-1 Electrical Characterization…………………………………….………………………….39
4-1-1 V-t & I-t Characteristics Analysis…………………………………...………39
4-1-2 I-V & P-V Characteristics Analysis…………………...…………………….40
4-1-3 Leakage Current Characteristics Analysis………………………..…………41
4-1-4 C-V Characteristics Analysis……………………………………….……….42
4-1-5 Electrical Behavior of HfZrO2 with Electric Field Cycling…………………43
4-1-6 Dipole Switching speed of HfZrO2 for STD and PDP samples………..……45
4-1-7 Retention Characteristic for STD and PDP samples………………………45

4-2 Structural Characterization…………………………………………………………..46
4-2-1 X-ray Diffraction (XRD)…………………………………………………..46
4-2-2 X-ray Photoelectron Spectroscopy (XPS)………………………..……….…47
4-2-3 Transmission Electron Microscopy (TEM)……………………………...…..47

Chapter 5 Conclusions & Future Works………………………………………………..…70
Reference……………………………………………………………………..………………71

Chapter 1
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