Simple piezoresistive pressure sensor
Jan 15, 2016
Simple piezoresistive pressure sensor
Simple piezoresistive accelerometer
Simple capacitive accelerometer
• Cap wafer may be micromachined silicon, pyrex, …• Serves as over-range protection, and damping• Typically would have a bottom cap as well.
C(x)=C(x(a))
Cap wafer
Simple capacitive pressure sensorC(x)=C(x(P))
ADXL50 Accelerometer
• +-50g
• Polysilicon MEMS & BiCMOS
• 3x3mm die
• Integration of electronics!
ADXL50 Sensing Mechanism• Balanced differential capacitor output• Under acceleration, capacitor plates move changing
capacitance and hence output voltage• On-chip feedback circuit drives on-chip force-feedback to re-
center capacitor plates (improved linearity).
Analog Devices Polysilicon MEMS
ADXL50 – block diagram• http://www.analog.com/en/mems-and-sensors/imems-accelerometers/products/index.html
Sense Circuit
Electrostatic Drive Circuit
Proof Mass
Digital Output
MEMS Gyroscope Chip
Rotation induces Coriolis
acceleration
J. Seeger, X. Jiang, and B. Boserhalteres
MEMS Gyroscope Chip
1m D
rive
0.01Å Sen
se
J. Seeger, X. Jiang, and B. Boser
Two-Axis Gyro, IMI(Integrated Micro Instruments Inc.)/ADI (fab)
Single chip six-degree-of-freedom inertial measurement unit (uIMU) designed by IMI
principals and fabricated by Sandia National Laboratories
TI Digital Micromirror Device
www.dlp.com
NEU/ADI/Radant/MAT Microswitches
SEM of NEU microswitch
Drain Source
Gate
Beam
Drain Gate Source
Beam
Drain
Gate
Source
Surface MicromachinedPost-Process Integration with CMOS20-100 V Electrostatic Actuation~100 Micron Size
Feedthrough Dielectric
Seal ring
Microbump
Landing ring
Package Substrate
MEMS
MAT Microswitch
http://www.radantmems.com/radantmems/switchoperation.html
Contact End of Switch Contact Detail
Packaged Plasma SourceTop View
Side View
Die in Hybrid Package
Fabrication
PR
Glass WaferCr/Au/TiW
Expose/Dev.TiW etch
ElectroplateGold
PR stripTiW/Au/Cr etch
Bond to 10 mm diam.glass chamberspiral coil
interdigitated capacitor
to vacuum system
SEM of Interdigitated Capacitor Structure
04/21/23
Spectrometer cross-section
Surface MicromachinedSpring System
ElectrostaticActuator Plates
04/21/23
Fabricated Microspectrometers
Intensity vs. Wavelength
0
0.2
0.4
0.6
0.8
1
1.2
450 500 550 600 650 700 750
Wavelength (nm)
Inte
ns
ity
(arb
. un
its
)
=515 nm=515 nm
FWHM = 25nmFWHM = 25nm
RP = 21RP = 21
= 575nm= 575nm
FWHM = 30nmFWHM = 30nm
RP = 20RP = 20
=625nm=625nm
FWHM = 39nmFWHM = 39nm
RP = 16RP = 16
Figure 1. Qualcomm Mirasol Display IMOD Structure Showing Light Reflecting off the Thin-film Stack and Mirror Interfering to Produce Color.
Optical MEMS Vibration SensorsOptical MEMS Vibration Sensors
Uniform cantilever beam Foster Miller - Diaphragm
Cantilevered paddle Cantilevered supported diaphragm
Optically interrogated MEMS sensorsOptically interrogated MEMS sensors
55 m length cantilevered paddle after 7 hours of B.O.E. releasing and lifted up with a
1m probe (~0.35m thick, 2m gap)
Courtesy Connie Chang-Hasnain
Courtesy Connie Chang-Hasnain
Micromachining Ink Jet Nozzles
Microtechnology group, TU Berlin
Microfluidic Chips
(UCLA, Fan)
(Gruning)
Gene chips, proteomics arrays.
NEMS: TOWARD PHONON COUNTING: Quantum Limit of Heat Flow.
RoukesGroupCal TechTito
From Ashcroft andMermin, Solid State Physics.
Other: NSF-Funded NSEC, Center for High-Rate Nanomanufacturing (CHN): High-rate Directed Self-Assembly of
Nanoelements
Nanotemplate: Layer of assembled nanostructures transferred to a wafer. Template is intended to be used for thousands of wafers.
Nanotube Memory DevicePartner: Nantero first to make memory devices using nanotubes
Properties: nonvolatile, high speed
at <3ns, lifetime (>1015 cycles), resistant to heat, cold, magnetism, vibration, and cosmic radiation.
Proof of Concept Testbed
Switch Logic, 1996, Zavracky, Northeastern
Inverter NOR Gate
Simple Carbon Nanotube Switch
Diameter: 1.2 nmElastic Modulus: 1 TPaElectrostatic Gap: 2 nmBinding Energy to Substrate: 8.7x10-20 J/nm
Length at which adhesion = restoring force: 16 nmActuation Voltage at 16 nm = 2 VResonant frequency at 16 nm = 25 GHzElectric Field = 109 V/m or 107 V/cm + Geom.
(F-N tunneling at > 107 V/cm)Stored Mechanical Energy (1/2 k x2 ) = 4 x 10-19 J = 2.5 eV4 x 10-19 = ½ CV2 gives C = 2 x 10-19 F << electrode capacitance! Much more energy stored in local electrodes than switch.
NEMS Switch Fabrication: To be discussed.
(a) Silicon chip with 500 nm of thermally grown oxide, 20 nm of tungsten, and PMMA. (b) Electron beam lithography was used to define features in the PMMA layer. An ICP etch was used to pattern the tungsten and etch down into the oxide. (c) A Cr/Au layer was evaporated and lifted off by removing the tungsten. (d) DEP was performed to assemble a small bundle of nanotubes traversing the trench between the two side electrodes.
NEMS Switch Operation
(a) Scanning electron micrograph of a switch. Atomic force microscopy scans before (b) and after (c) switch actuation. (d) Initial (solid lines), second (dashed lines), and third (dotted lines) I-V sweeps for the device seen in (a-c). This device had a vertical gap of 24 nm and a trench width of 195 nm.
NEMS Switch Problems During Operation
NEMS Switch Electro-Mechanical Model
Carbon Nanotube for Adhesion Measurement
Biological Nanomotor