Page 8 - Microsensors, MEMS and Smart Devices - Gardner Varadhan and Awadelkarim

CONTENTS vii

5.3.3 Selective Etching of n-Type Silicon by Pulsed 131
Potential Anodisation
5.3.4 Photovoltaic Electrochemical Etch-Stop Technique 131
(PHET)
5.4 Dry Etching 134
5.5 Buried Oxide Process 137
5.6 Silicon Fusion Bonding 138
5.6.1 Wafer Fusion 138
5.6.2 Annealing Treatment 138
5.6.3 Fusion of Silicon-Based Materials 139
5.7 Anodic Bonding 140
5.8 Concluding Remarks 143
References 143

6 Silicon Micromachining: Surface 145
6.1 Introduction 145
6.2 Sacrificial Layer Technology 145
6.2.1 Simple Process 146
6.2.2 Sacrificial Layer Processes Utilising more than One 151
Structural Layer
6.3 Material Systems in Sacrificial Layer Technology 155
6.3.1 Polycrystalline Silicon and Silicon Dioxide 156
6.3.2 Polyimide and Aluminum 156
6.3.3 Silicon Nitride/Polycrystalline Silicon and 157
Tungsten/Silicon Dioxide
6.4 Surface Micromachining using Plasma Etching 158
6.5 Combined 1C Technology and Anisotropic Wet Etching 162
6.6 Processes Using Both Bulk and Surface Micromachining 166
6.7 Adhesion Problems in Surface Micromachining 170
6.8 Surface Versus Bulk Micromachining 172
References 172

7 Microstereolithography for MEMS 173
7.1 Introduction 173
7.1.1 Photopolymerisation 174
7.1.2 Stereolithographic System 178
7.2 Microstereolithography 179
7.3 Scanning Method 181
7.3.1 Classical MSL 181
7.3.2 IH Process 182
7.3.3 Mass-IH Process 184
7.3.4 Super-IH Process 186
7.4 Two-photon MSL 189
7.5 Other MSL Approaches 192
7.6 Projection Method 193
7.6.1 Mask-Projection MSL 193
7.6.2 Dynamic Mask-Projection MSL 196