不同於傳統合金設計，高熵合金採用多元合金的組成使其具備抗腐蝕、高強度、高熱穩定性等特殊性質，其中以鈷鉻鐵鎳作為基底的合金因具備高強度等絕佳的機械性質成為備受矚目的材料。本研究將鈷鉻鐵鎳中熵合金薄膜利用脈衝磁控濺鍍系統沉積於矽(100)基板上，透過田口實驗規劃法中的L16 (45)直交表進行製程優化。實驗中調整五種鍍膜參數（基板偏壓、基板溫度、工作氣壓、基板轉速及脈衝電壓）至四個層級做為控制變因，並設定低電阻、低粗糙度及高硬度為性質優化的指標。製備完薄膜後，首先計算每組參數的訊雜比，得出三組最佳參數後分別進行確認試驗，獲得低電阻（98.2±0.8 μΩ·cm）、低粗糙度（0.5±0.1 nm）及高硬度（9.28±0.33 GPa）的結果。接著經變異數分析，發現影響電阻最敏感的因子為基板偏壓，而影響粗糙度及硬度最顯著的因子皆為基板升溫。除了性質量測，亦進行微結構的分析，包含利用能量散佈分析儀確認元素含量多寡及分布均勻度，利用X光繞射儀分析晶體結構及優選方向，發現部分薄膜呈現面心立方堆積（FCC）及六方最密堆積（HCP）的雙相結構，更有趣的是，本研究發現可以透過濺鍍參數的調整，控制薄膜的優選方向。此外，也從穿透式電子顯微鏡分析結果發現薄膜中含有大量的奈米雙晶，不同薄膜濺鍍參數如何影響微結構及性質將在本研究中詳細討論。

Different from conventional alloy design, high entropy alloy (HEA) has attracted much interest due to its superior properties, such as high hardness, corrosion resistance and thermal stability. Among various HEAs, CoCrFeNi-based HEAs have been investigated a lot due to its high toughness. In present study, CoCrFeNi medium entropy alloys have been prepared by pulsed DC magnetron sputtering system on Si (100) substrate. The effects of five deposition parameters, including substrate bias, substrate temperature, working pressure, rotation speed and frequency, have been investigated using Taguchi experimental method and analysis of variance (ANOVA). Based on a L16 (45) orthogonal array and the signal-to-noise ratio results, the optimized parameters for low electrical resistivity (98.2±0.8 μΩ·cm), low surface roughness (0.5±0.1 nm) and superior hardness (9.3±0.2 GPa) are achieved. In addition, the chemical composition was studied by energy dispersive X-ray spectrometry (EDS). The X-ray Diffractometer (XRD) results show that a dual phase of FCC-HCP is formed in some specimens. Moreover, some of specimens possess FCC (111) preferred oriented, while the others are FCC (200) preferred oriented. The Transmission electron microscope (TEM) results indicate that abundant nanotwins are formed in CoCrFeNi thin films. The link between deposition parameters, microstructure and properties has been discussed in this study.

摘要 i
Abstract ii
致謝 iii
Contents iv
List of Figures vii
List of Tables x
Chapter 1 Introduction 1
Chapter 2 Literature Review 3
2.1. Design of Experiment (DOE) 3
2.1.1. Taguchi Method 3
2.1.2. Analysis of Variance (ANOVA) 6
2.2. Thin Film Deposition 7
2.2.1. Physical Vapor Deposition 7
2.2.2. Film Formation Mechanism and Zone Model 8
2.3. Characteristics of High Entropy Alloys 12
2.3.1. High Entropy Alloy Thin Films 12
2.3.2. Characteristics of CoCrFeNi Medium Entropy Alloy 13
2.3.3. Nanotwin Structure in High Entropy Alloy 15
Chapter 3 Experimental Methods 18
3.1. Sample Preparation and Deposition Process 18
3.1.1. Target Manufacturing 18
3.1.2. Substrate Preparation and Coating Process 19
3.2. Characterization Methods 22
3.2.1. Inductively Coupled Plasma Mass Spectrometry (ICP-MS) 22
3.2.2. Scanning Electron Microscopy- Energy Dispersive X-ray Spectrometry (SEM-EDS) 23
3.2.3. X-ray diffractometer (XRD) 24
3.2.4. Transmission Electron Microscope (TEM) 25
3.2.5. Focus Ion Beam Microscope (FIB) 27
3.3. Properties Measurement 28
3.3.1. Four-Point Probe 28
3.3.2. Scanning Probe Microscope (SPM) 30
3.3.3. Laser Curvature Measurement 31
3.3.4. Nanoindentation 31
Chapter 4 Results and Discussion 33
4.1. Microstructure 33
4.1.1. Chemical Composition 33
4.1.2. Thickness and Deposition Rate 36
4.1.3. Crystal Structure and Texture 38
4.1.4. Cross-sectional Microstructure 47
4.2. Properties 48
4.2.1. Resistivity 48
4.2.2. Surface Roughness 52
4.2.3. Residual Stress 55
4.2.4. Hardness 56
4.3. Other Observations 59
4.3.1. Formation of Dual Phase 59
4.3.2. Preferred Orientation 61
Chapter 5 Conclusions 66
Chapter 6 Future Work 67
Reference 72

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