1. UNCLASSIFIED
UNCLASSIFIED
A Novel Vacuum Packaging Design Process
for MEMS Quadruple-Mass Gyroscopes
Student: Rohan Deshmukh
Mentors: Ryan Knight, Dr. William Nothwang
Objective
Develop a novel process that packages Micro-Electrical-Mechanical Systems (MEMS) quadruple-mass gyroscopes
(QMGs) at sub-mTorr regime in order to enhance the device’s quality factor (Q-factor). Future gyroscopes for
positioning, navigation, and timing (PNT) systems require both improved performance and longevity.
Results
Conclusion
This project demonstrates the importance of vacuum packaging for MEMS gyroscopes in order to improve the device’s
performance. A properly designed heating profile can allow for an ultra-low packaging pressure to be obtained. The
internal chemistry during the heating profile can be monitored using an RGA and, at the same time, can provide insight
into performance of heating profile and hermetic sealing. Through implementing an in-situ approach while mitigating
state function dependence, precise measurements of internal vacuum pressure can be obtained. Putting all of these
intertwined blocks together, the foundation of better performing MEMS gyroscopes can be built.
Experimental Procedure
Thermal Fluctuation Experiment
•Goal: Shunt temperature effects on PG voltage output
•Approach: Wheatstone bridge configuration
Heating Profile Design
•Goal: Vacuum package and hermetically seal QMG
•Approach: Suss SB8e Wafer Bonder’s recipe creator
Residual Gas Analyzer (RGA) Experiment
•Goal: Measure performance of heating profile design
•Approach: RGA analysis using Pfeiffer Prisma 80 QME-200
Quality Factor Experiment
•Goal: Measure Q-factor of vacuum packaged QMG
•Approach: Frequency response of voltage signal
Component
Name
Outgassing
Properties
Package (Al2O3,
Electroplated Ni &
Au)
Low CTE, traps H2
& moisture
Lid (Kovar,
Electroplated Ni &
Au)
Traps H2 &
moisture
Preform (80/20
Au/Sn)
Release CO2 when
melting
Superglue (Ethyl
Cyanoacrylate)
Releases CxHy ,
CO, CO2 when
heated
Packaging Procedure
After sealing
Q = 100