Page 271 - MEMS Mechanical Sensors

260 Index

Bonding (continued) See also Pressure sensors
silicon fusion, 29–30 Capacitive techniques, 92–94
vacuum, 32 noise and, 94
Boron etch stop technique, 23 types of, 94
Bossed diaphragms, 128–29 See also Mechanical transduction
analysis, 128–29 techniques
defined, 128 Capacitive torque sensors, 160–62
deflection of, 129 Ceramic packages, 58–59
fabrication, 131 Chemical vapor deposition (CVD), 13
geometry, 128 atmospheric pressure (APCVD), 13
resistor placement on, 133 low-pressure (LPCVD), 13
See also Diaphragm-based pressure sensors; plasma enhanced (PECVD), 13
Diaphragms Closed loop accelerometers, 177–80
Bourdon tubes, 122–23 actuation mechanisms, 177
defined, 122 advantages, 177
elements, 122 analog force-feedback, 177–79
use of, 123 defined, 177
See also Pressure sensors digital feedback, 179–80
Brazing, 65 drawback, 177
Breakdown voltage, 4 See also Accelerometers
Commercial gyroscopes, 204–6
C ADXRS, 204–5
die photo, 205
Calorimetric flow sensors, 220–23
illustrated, 204
data for, 222
measurement curve, 224 Silicon Sensing Systems, 204
required elements, 220 Commercial micromachined accelerometers,
192–95
schematics, 223
ADXL50, 192–93
SEM photograph, 223
sensitivity, 222 ADXL105, 193
See also Flow sensors; Thermal flow sensors ADXL150, 193
Capacitance, pressure vs., 138 ADXL202, 193–94
MMA1201P, 194–95
Capacitance sensors
cross-section through SOI, 139 MS7000/MS8000, 195
differential, 93 Commercial thermal flow sensors, 225–29
bidirectional, 226
displacement, 92
data for, 230
simplicity, 92
Capacitive accelerometers, 182–85 Fraunhofer Institute, 227
in analog force-feedback loop, 178 gas, 229
HSG-IMIT, 227–28
defined, 182
Sensirion, 229
high-performance bulk-micromachined, 183
in open-loop mode, 183 See also Thermal flow sensors
surface/bulk-micromachined, 186 Coriolis force, 195, 197, 198
Coriolis force flow sensors, 236–38
surface-micromachined, 184 cross-sectional view, 237
three-axis, 189, 190
Yazdi/Najafi, 185 data, 238
See also Accelerometers defined, 236–37
Capacitive microphones, 143–44 disadvantages, 238
fabrication, 237
Capacitive pressure sensors, 137–39
See also Force transfer flow sensors
acceleration compensated quartz, 137
defined, 137 Corrugated diaphragms, 129
drawbacks, 138 CoSolveEM, 45
CoventorWare, 44–47
silicon/Pyrex, 137