本文研究目標主要在探討結合微系統技術與一般特徵尺寸下的機構設計原理，發展一種便於微組裝的微爪機構，研究的範圍包含剛性結構及撓性整體結構。本研究先探討幾種不同原理的組裝技術，如靜電力、表面張力、磁力及雙薄膜的概念。而在剛體結構的設計方面，研究方向是空間中工作距離的大小及在單一的微爪機構元件上具有多重的夾取功能。在撓性結構的研究上，探討一般尺度的機構及微尺度的撓性機構在運動表現上的關係，相關結果可以作為進一步製程設計的參考。本文中提出一套轉換剛性機構為撓性機構之系統化流程，並可引申至微爪機構之設計在，完成以上相關系統化之微爪機構設計之後，將進行FEM分析了解微爪機構在作動時的應力狀態、被驅動時的內部溫度分佈、進行抓取微細物件時撓性接頭的扭曲變化情形等，以便修正之前所給定之微爪機構之系統尺寸。

Most of the microgrippers developed in recent years still lack of the systematic mechanism design background in the overall design scope of microgripper. The main objective of this investigation is to find new possibilities of design concept in order to enhance the design scope of microgripper.
This thesis presents the design and analysis of microgripper for microassembly that are based on the mechanism design perspective, which particularly involves the 3-D working space and planar compliant microgripper. Several feasible solutions of the microgripper with 3-D working space are presented include the use of molten solder self-assembly, hinge mechanism, shape memory alloy, electrostatic-force assembly, and magnetic-force assembly. An atlas of 28 types of planar compliant linkages for two-finger microgripper is presented based on the systematic design procedure. The FEM simulation shows the preliminary satisfactory results that reveal the good agreement with the expected kinematic motion. It can be concluded that the mechanism design concept presented in this study can be integrated into the design work of micro scale actuating device.

TABLE OF CONTENTS

TABLE OF CONTENTS I
ABSTRACT OF THE THESIS IV
LIST OF FIGURES V
LIST OF TABLES VIII
LIST OF TABLES VIII
ACKNOWLEDGEMENTS IX
CHAPTER I INTRODUCTION 1
1.1 Background of MEMS and the Needs of Microgripper 1
1.2 Literature Review 2
1.2.1 Microgripper Based on Electrostatic Microactuators 3
1.2.2 Microgripper Based on Thermal Microactuators 4
1.2.3 Microgripper Based on Piezoelectric Microactuator 10
1.2.4 Microgripper Based on Electromagnetic Microactuator 11
1.2.5 Fabrication Processes Used To Realize Microgripper 12
1.3 Motivation and Description of Approach 13
1.4 Objective and Thesis Overview 14
CHAPTER II MICROGRIPPER FABRICATIONS 16
2.1 Surface Micromachining 16
2.1.1 Thin Film Technique 17
2.1.2 Photolithography 17
2.1.3 Etching Techniques 19
2.1.3.1 Wet Etching 20
2.1.3.2 Dry Etching 20
2.1.4 Doping techniques 22
2.1.5 Sacrificial Layer 23
2.1.6 Present Limitations of Surface Micromachining 24
2.2 Hexsil Process 25
2.3 Other High Aspect Ratio MEMS 25
2.3.1 Bulk Micromachining 25
2.3.2 Hinged Structures 26
2.3.3 Deep Reactive Ion Etching (DRIE) 27
2.3.4 LIGA 28
2.3.5 LIGA-Like Technique 28
CHAPTER III DESIGN AND ANALYSIS OF MICROGRIPPER 29
3.1. Introduction to Spatial Three-Finger Microgripper Design 29
3.1.1 Concept Design Based on Three Dimensional Working Space 31
3.1.2 Various Approach Principles Based on the Developed Microactuators 31
3.1.3 Theoretical Analysis and Finite Element Method (FEM) 38
3.1.4 Observation of Simulation Results and Discussions 42
3.1.5 Fabrication 46
3.2. Introduction to Planar Two-Finger Microgripper Design 47
3.2.1 Concept Design Based on Mechanism Approach 47
3.2.2 Transformation of Compliant Mechanism 49
3.2.3 Theoretical Analysis and Finite Element Method (FEM) 57
3.2.4 Observation of Simulation Results and Discussions 62
3.2.4.1 Stiffness Hierarchy 66
3.2.4.2 Compliant Microgripper Design with Stiffness Hierarchy 82
3.2.5 Fabrication 96
CHAPTER IV MICROGRIPPER BASED ON HEXSIL PROCESS 98
4.1 Current Challenging of Hexsil Processing Issues 98
4.2 Microgripper Fabrication Design Based on Hexsil Process 99
4.2.1 Preprocess Wafer Preparation 99
4.2.2 Silicon Wafer Mold Micromachining 100
4.2.3 Protective Layer Deposition 100
4.2.4 Sacrificial Layer Deposition 101
4.2.5 Structural Layer Deposition 101
4.2.6 Mold Ejection Release Etching 102
CHAPTER V CONCLUSION 107
5.1 Summary 107
5.2 Suggested Future Research 108
REFERENCES 110
APPENDIX I 116
APPENDIX II 118

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