共振型加速度計已成為運動傳感、慣性導航和結構健康監測等廣泛應用中不可或缺的元件。本論文針對電容式和壓電式共振型加速度計進行了全面的探索，涵蓋了它們的設計、製造和性能分析。最初的重點是電容式共振型加速度計，其中提供了對設計原理、模擬、製程和實驗架設的詳細說明。
然而，實驗結果揭示了電容式設計的局限性，例如高饋通、低訊雜比、對高直流電壓的要求以及低製造良率，其脆弱性和封裝的挑戰也阻礙了電容式加速度計的穩健性和可靠性。
在這些挑戰的推動下，本文探討了壓電式共振型加速度計作為替代方法，研究其設計考量、工作原理和關鍵性能參數，接著開發了雙軸氮化鋁共振型加速度計的專用製程，其實驗架設和測量結果為元件的靈敏度、雜訊水平和頻率響應提供了寶貴的見解。
一具備高靈敏度之雙軸壓電共振式加速度計首次被開發，在廣泛的測試下，x軸與y軸的靈敏度分別為53 Hz/g與73 Hz/g、運動電阻僅56 kΩ，其解析度高達7.5 mg或是0.67°。為了產生1 g的加速度，元件將傾斜90°，由於產生的應力，樑共振器中會產生相應的頻率變化，所有共振器均已使用45°步進傾斜進行測試以驗證結果。
該壓電式共振加速度計展現了創紀錄的低運動阻抗，使得無需複雜的電路即可進行測量，其全夾緊結構也使其更適合進行真空封裝以保證測量的精度。
相較之下，壓電式共振加速度計在運動阻抗和相位雜訊方面優於電容式共振加速度計。在主軸傾斜偵測表現出令人滿意的靈敏度外，同時實現最小化交叉軸敏感性。動態測量驗證其在不同加速度條件下的響應能力和準確性，而掃描測試則確認在各種傾斜角度下的線性度和精確測量能力。
本研究極大地促進了共振型加速度計的理解和進步，對電容式和壓電式元件的詳細探索、自行製造技術以及詳細的實驗測量為未來的研究和開發奠定了堅實的基礎。未來的工作目標為性能提升、評估在複雜條件下的元件行為、最小化交叉軸敏感性、提高封裝穩定性、優化製程並實現元件性能的一致性。
總體而言，本文為開發具有廣泛應用的高性能共振型加速度計奠定了基礎，這項研究的發現和進步有可能徹底改變運動傳感、慣性導航和結構健康監測系統，從而在各個領域實現更準確、更可靠的測量，這項研究取得的進展為共振型加速度計技術的進一步創新和探索奠定了基礎。

Resonant accelerometers have become indispensable devices in a wide range of applications, including motion sensing, inertial navigation, and structural health monitoring. This thesis presents a comprehensive exploration of capacitive and piezoelectric resonant accelerometers, covering their design, fabrication, and performance analysis. The initial focus is on the capacitive resonant accelerometer, where a detailed understanding of design principles, simulation techniques, fabrication processes, and experimental setup is provided.
However, experimental results reveal limitations in the capacitive design, such as high feedthrough and low signal-to-noise ratio, along with the requirement for high DC voltage and low fabrication yield. Fragility and packaging challenges also hinder the robustness and reliability of capacitive accelerometers.
Motivated by these challenges, the thesis explores the piezoelectric resonant accelerometer as an alternative approach. It investigates design considerations, working principles, and key performance parameters, followed by the development of a specialized fabrication process for dual-axis AlN-based resonant accelerometers. Experimental setup and measurement results provide valuable insights into sensitivity, noise levels, and frequency response.
For the first time, a two-axis piezoelectric accelerometer with satisfactory sensitivity of 53 Hz/g in the x-axis and 73 Hz/g in y-axis, low Rm of 56 kΩ, and high resolution of 7.5 mg or 0.67° is developed and extensively tested. To induce an acceleration of 1 g, the device is tilted by 90°, resulting in a corresponding frequency change in the beam resonator due to the generated stress. All the resonators have been tested using a 45° step tilt to validate the results.
The piezoelectric resonant accelerometer exhibits a record-low motional resistance, allowing measurements without complex circuitry. Its fully clamped structure proves more suitable for vacuum packaging, ensuring measurement accuracy.
Comparatively, the piezoelectric resonant accelerometer outperforms the capacitive type in terms of motional resistance and phase noise. It demonstrates satisfactory sensitivities in both primary and cross-axes, with minimal cross-axis sensitivity. Dynamic measurements validate its responsiveness and accuracy under varying acceleration conditions, while sweep tests confirm linearity and precise measurement capabilities across a wide range of tilt angles.
This study significantly contributes to the understanding and advancement of resonant accelerometers. The detailed exploration of capacitive and piezoelectric approaches, in-house fabrication techniques, and comprehensive experimental measurements establish a solid foundation for future research and development. Future work aims to enhance performance, evaluate behavior under complex conditions, minimize cross-axis sensitivity, improve packaging robustness, optimize fabrication processes, and achieve higher consistency in device performance.
Overall, this thesis lays the groundwork for the development of high-performance resonant accelerometers with broad applications. The findings and advancements made in this study have the potential to revolutionize motion sensing, inertial navigation, and structural health monitoring systems, enabling more accurate and reliable measurements in various fields. The progress made in this research sets the stage for further innovation and exploration in resonant accelerometer technology.

ABSTRACT i
摘要 iv
ACKNOWLEDGEMENT vi
TABLE OF CONTENTS x
LIST OF FIGURES xiii
LIST OF TABLES 18
CHAPTER 1 : Introduction 19
1.1 Accelerometer Parameters 27
1.2 Piezoresistive Accelerometer 28
1.3 Capacitive Accelerometer 30
1.3.1 Non-Resonant Type 32
1.3.2 Resonant Type 32
1.4 Piezoelectric Accelerometer 33
1.5 Thesis Contribution 35
1.6 Thesis Organization 37
CHAPTER 2 : Capacitive-Based Resonant Accelerometer 41
2.1 Preface 41
2.2 Generic parameters in Resonant Sensing 42
2.3 Resonant Accelerometer 43
2.3.1 Device Design and Working Principle 44
2.3.2 Simulation Analysis 47
2.4 Fabrication Process 50
2.4.1 Detailed Intermediate Fabrication Steps 52
2.4.2 Zero Mark 53
2.4.3 Metallization 54
2.4.4 PECVD TEOS Deposition as Oxide Hard Mask 56
2.4.5 Deep Reactive Ion Etching (DRIE) 57
2.4.6 Backside Si Etching 60
2.4.7 49% HF Release 62
2.5 Measurement Setup & Results 62
2.5.1 Open-loop Resonator Characterization 62
2.5.2 Closed-loop Resonator Characterization 67
2.5.3 Tilt Characterization 70
2.6 Summary 72
CHAPTER 3 : Piezoelectric Resonant Accelerometer 74
3.1 Introduction 74
3.2 Design & Working Principle 76
3.2.1 Structure Design & Simulation 76
3.3 Working Principle 82
3.4 Fabrication 83
3.4.1 In-house Process Flow 83
3.5 Other Process Insights 87
3.5.1 Molybdenum Metal Bottom Electrode Etching Process 87
3.5.2 AlN piezoelectric layer etching process 88
3.5.3 Chromium Gold Top Electrode Lift-off Process 88
3.5.4 Microstructure Shape Defined Etching Process 89
3.5.5 Backward dry etching and release process 90
CHAPTER 4 : Measurement Setup 94
4.1 Open-loop resonator electrical characterization setup 94
4.2 Resonator optical characterization 97
4.3 Resonator closed-loop characterization setup 98
4.4 Resonant Accelerometer Static Tilt characterization setup 103
4.5 Resonant Accelerometer Dynamic Tilt characterization setup 104
CHAPTER 5 : Results & Discussions 109
5.1 Open-loop Resonator characterization 109
5.1.1 X1R & X2R Resonator 109
5.1.2 Y1R & Y2R Resonator open-loop characterization 109
5.1.3 Discussion 111
5.2 Resonator MBVD model 112
5.3 Resonator optical characterization results 115
5.4 Resonator closed-loop characterization results 118
5.4.1. Phase Noise 118
5.4.2 Discussion 122
5.4.3 Frequency Drift and Allan-Deviation 123
5.5 Accelerometer static g characterization results 127
5.5.1 X1R Resonator Tilt Characterization 128
5.5.2 X2R Resonator Tilt Characterization 132
5.5.3 Y1R Resonator Tilt Characterization 135
5.5.4 Y2R Resonator Tilt Characterization 137
5.5.5 Summary 140
5.6 Differential Sensitivity 141
5.6.1 Real-time Differential Measurement 143
5.7 Accelerometer dynamic g characterization results 146
CHAPTER 6 : CONCLUSION & FUTURE WORK 150
6.1 Comparison of Capacitive and Piezoelectric Resonant Accelerometers 152
6.2 Unveiling the Potential: Advancements in Capacitive and Piezoelectric Resonant Accelerometers 154
6.3 Future Work 156
BIBLIOGRAPHY 158

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