Toward Inertial-Navigation-on-Chip: The Physics and Performance Scaling of Multi-Degree-of-Freedom Resonant MEMS Gyroscopes

134 Pages·2019·5.171 MB·English

by  Haoran Wen

Springer Theses
Recognizing Outstanding Ph.D. Research
Haoran Wen

Toward Inertial-
Navigation-on-Chip
The Physics and Performance Scaling of
Multi-Degree-of-Freedom Resonant
MEMS Gyroscopes
Springer Theses
Recognizing Outstanding Ph.D. Research
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Haoran Wen
Toward Inertial-Navigation-
on-Chip
The Physics and Performance Scaling of
Multi-Degree-of-Freedom Resonant MEMS
Gyroscopes
Doctoral Thesis accepted by Georgia Institute
of Technology, Atlanta, GA, USA
HaoranWen
SchoolofElectricalandComputerEngineering
GeorgiaInstituteofTechnology
Atlanta,GA,USA
ISSN2190-5053 ISSN2190-5061 (electronic)
SpringerTheses
ISBN978-3-030-25469-8 ISBN978-3-030-25470-4 (eBook)
https://doi.org/10.1007/978-3-030-25470-4
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To my loving family
’
Supervisor s Foreword
Haoran Wen’s thesis focuses on performance scaling of Coriolis vibratory gyro-
scopes and development of next-generation multi-axis gyroscopes using
microelectromechanicalsystems(MEMS)technologyforhigh-performancesingle-
chip inertial measurement units (IMU). It covers a comprehensive study of the
physics of resonator gyroscopes as well as novel engineering and microfabrication
solutionstokeyperformancelimitsinMEMSresonatorgyroscopes,settingitapart
fromotherthesesinthisarea.
MEMS IMUs have been widely used in consumer electronics and automotive
applications for motion detection and safety control. Improving their performance,
robustness, and power consumption can broaden their uses to more advanced
applications such as health informatics and indoor navigation. Conventional
MEMS gyroscopes are limited by trade-offs between their performance and their
power consumption and robustness. This thesis covers a thorough study of the
physics of vibratory gyroscopes and provides new insight into the error sources
andperformancescalingofMEMSvibratorygyroscopestobreakthroughthetrade-
offsfornext-generationMEMSgyroscopesandIMUs.Theoretical,numerical,and
experimental studies are well documented in this thesis, making it a valuable
referenceforfutureresearchersinthisfield.Basedonthetheoreticalstudies,novel
designsandfabricationplatformaredeveloped,featuringhighlyefficientnano-gap
transduction and quadrature-error compensation that enable high-frequency reso-
nant-type triaxial gyroscopeson a chip withhigh sensitivitiesand nanometer-scale
actuations.Inaddition,thisthesisalsoaddressedothercriticalperformancelimitsin
MEMS gyroscopes such as nonlinearity and energy dissipation. Altogether, it
created wafer-level-packaged single-chip IMU prototypes with co-fabricated high-
frequencytriaxialgyroscopesandhigh-bandwidthtriaxialaccelerometers.Thepro-
totypes demonstrated performance among the best for the IMUs to date while
possessing unmatched robustness. The small size and low actuation of the gyro-
scopes also offer the potentials for robust flexible substrate integration and
low-power operation, showing a path toward the next-generation IMUs for future
vii
viii Supervisor’sForeword
low-powerapplicationsincludingwearablehealthinformatics,personalnavigation,
andotheradvancedharsh-environmentindustrialapplications.
In summary, Haoran’s dissertation work provided deeper understandings of the
physics of MEMS gyroscopes, offered innovative solutions to some of the most
intriguing problems, and led to a unique enabling MEMS fabrication platform. I
believealloftheabovehavesignificantimpactsondevelopingthenext-generation
MEMSIMUsandcanbeofgreatvaluetoresearchersinthefield.
GeorgiaInstituteofTechnology FarrokhAyazi
Atlanta,GA,USA
June2019
Acknowledgments
First,Iwouldliketoexpressmysincereappreciationandgratitudetomyadvisorand
mentor,ProfessorFarrokhAyazi,notonlyforhissupportandguidancethroughout
myPh.D.studybutalsoforgivingmethechancetodevelopmyresearchinafieldI
like.Ialsowanttothankhimforplacinghistrustandconfidenceinmewithvarious
opportunities,whichallowedmetogainexperienceandskillsthatareinvaluablefor
my future career. I would like to thank my dissertation committee members,
Professor Chandra Raman, Professor Peter J. Hesketh, Professor Phillip N. First,
and Professor Simon Sponberg for their interest in my research and for spending
theirprecioustimeonreviewingthisdissertationandprovidingvaluablefeedback.
It has been a great pleasure and honor to work with and become friends with
many former and current members of the IMEMS group. I would like to thank
Dr. Diego Serrano, Dr. Roozbeh Tabrizian, Dr. Arashk Shirazi, and Dr. Yaesuk
Jeong for all their invaluable discussions and suggestions and Pantani Liu, Sam
Wisher,andRyanLeifortheircollaborativehelp.IgivemyspecialthankstoAnosh
Daruwalla, Benoit Hamelin, and Mojtaba Hodjat-Shamami. Together, we survived
cleanroom.Inaddition,Iappreciateallthehelpsprovidedbythecleanroomstaffsat
GeorgiaInstituteofTechnology,whichmadethisworkpossible.
Iwanttoexpressmydeepestgratitudetomyparents,fortheirunconditionallove
andsupporthavegivenmethecourageandconfidencetochasemydreams.Lastbut
notleast,IwishtothankDongxiunanMaoforhersupportandpatienceduringmy
graduate studies and for always being there for me to keep me positive and
motivated.
ix
Contents
1 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.1 InertialNavigationSystem. . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.2 EvolutionofGyroscopes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.3 EvolutionofMEMSGyroscopes. . . . . . . . . . . . . . . . . . . . . . . . 6
References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
2 ThePhysicsofResonantMEMSGyroscopes. . . . . . . . . . . . . . . . . . 13
2.1 PrincipleofOperation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
2.2 Non-idealMEMSGyroscope. . . . . . . . . . . . . . . . . . . . . . . . . . . 18
2.2.1 MechanicalModel. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
2.2.2 ElectromechanicalTransductionandInterfaceCircuits. . . 22
2.2.3 Drive-LoopTransductionandControl. . . . . . . . . . . . . . . 23
2.2.4 Sense-ModeDetection. . . . . . . . . . . . . . . . . . . . . . . . . . 24
2.2.5 ElectrostaticTuning. . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
2.2.6 ElectricalNoiseandErrors. . . . . . . . . . . . . . . . . . . . . . . 29
2.3 PerformanceParameters. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
2.3.1 Scale-FactorandBandwidth. . . . . . . . . . . . . . . . . . . . . . 30
2.3.2 AngleRandomWalk. . . . . . . . . . . . . . . . . . . . . . . . . . . 31
2.3.3 BiasInstabilityandLong-TermDrift. . . . . . . . . . . . . . . . 32
References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
3 BiasControlinPitchandRollGyroscopes. . . . . . . . . . . . . . . . . . . . 35
3.1 QuadratureCancellation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
3.1.1 SlantedElectrode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
3.1.2 FabricationImplementation. . . . . . . . . . . . . . . . . . . . . . 38
3.2 KOH-EtchedQuad-MassGyroscope. . . . . . . . . . . . . . . . . . . . . 39
3.2.1 DesignofWet-Etched-OnlyGyroscope. . . . . . . . . . . . . . 39
3.2.2 SimulationResults. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
3.2.3 FabricationProcess. . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
3.2.4 ExperimentalCharacterization. . . . . . . . . . . . . . . . . . . . 44
3.3 DissipationandIn-PhaseBiasStabilization. . . . .. . . . . . . . . . .. 49
xi