(1)Introduction of MEMs

8/12/2019 (1)Introduction of MEMs

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TFIT-2 Department of Electronics Engineering and Computer, TFITDepartment of Electronics Engineering and Computer, TFIT

What is MEMs ?What is MEMs ?

MicroelectromechanicalMicroelectromechanical Systems, or MEMS,Systems, or MEMS,

areare integrated micro devicesintegrated micro devices oror systemssystems

combining electrical and mechanicalcombining electrical and mechanicalcomponentscomponents..

They are fabricated usingThey are fabricated using integrated circuitintegrated circuit

(IC) batch processing techniques and can(IC) batch processing techniques and canrange in size fromrange in size from micrometers to millimetersmicrometers to mill imeters..

These systems can sense, control and actuateThese systems can sense, control and actuate

on the micro scale, and function individually oron the micro scale, and function individually orin arrays to generate effects on thein arrays to generate effects on the macromacro

scalescale..


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History of MEMS Technology (History of MEMS Technology ())

Richard Feynman says, Theres Plenty of Room at the Bottom- Presentation given Decmber 26, 1959 at California Institute of Technology

- Tries to spur innovative miniature fabrication techniques for micromechanics

- Fails to generate a fundamentally new fabrication technique

Westinghouse creates the Resonant Gate FETin 1969- Mechanical curiosity based on new microelectronics fabrication techniques

Bulk-etched silicon wafers used as pressure sensors in 1970s

Kurt Petersen published Silicon as a Structure Materialsin 1982- Reference for materials properties and etched data for silicon

Early experiments in surface-micromachined polysilicon in 1980s

- First electrostatic comb drive actuators

- Micropositioning disc drive heads Micromachining leverages microelectronics industry in late 1980s

- Widespread experimentation and documentation increases public interest


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History of MEMS Technology (History of MEMS Technology ())

Early transduction and actuation methods produce simple actuators

- Piezoresistive , capacitive , field emitters , electrostatic , bimorph , piezoelectric

Methods of micromachining aimed toward improving sensors- Thermal and electrical isolation between layers with suspended structures

Government agencies start large MEMs support programs

- AFORS supports basic research in materials and MEMs research

- DARPA creates MUMPS foundry service with MCNC in 1993

- NIST supports commercial foundries for CMOS and MEMS

Chris Pister (UCLA) creates first micromachined hinge in 1992

- Hinged features open possibilities for pseudo-3D structure and assembly

Later actuation and fabrication methods produce advanced systems

- Deep reactive ion etching , laser machining , fluidics , tunneling , deep UV

shape memory alloys , magnetic materials , extrusion , combustion


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Technology Trend and RoadmapTechnology Trend and Roadmap


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Micromachine center

Market of MEMs (Japan)Market of MEMs (Japan)


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Market of MEMs (USA)Market of MEMs (USA)


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MEMsMEMs of Electronicsof Electronics


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Sensor and ActuatorSensor and Actuator


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WordwideWordwide MEMs GrowthMEMs Growth


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1.Hard disk driver heads

2.Inkjet printer heads

3.Heart pace makers

4.In-vitro diagnostic devices

5.Hearing aids

6.Pressure sensors

7.Chemical sensors

1.Drug-delivery systems

2.Optical switches

3.Lab-on chip system

4.Magneto-optical heads5.Projection light valves

6.Coil-on-chip

7.Micro-relays

8.Micro-motors

1.IT peripherals

2.Medical / Biomedical Engineering application

3.Industry and automation

4.Tele-communications

5.Automotive applications

6.Environmental monitoring

2002


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IC -,,,

,

,

-,,,

-,,,, - -()-, ..()-,,,,()-,, -,,


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Defense ApplicationDefense Application


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Commercial ApplicationCommercial Application


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MicroMicro--Technology ClassificationTechnology Classification


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MultiMulti --technology for MEMS applicationstechnology for MEMS applications

Mechanical

Chemical

Materials

Biological

Electronic Physical

MEMs

Optical


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MicrosensorsMicrosensors of Classificationof Classification

Thermal sensorsThermal sensors

--Thermocouples,Thermocouples, ThermoresistorsThermoresistors, Thermal flow, Thermal flow--raterate

sensors.sensors.

Radiation sensorsRadiation sensors

--Photodiodes, Phototransistors, Charge coupled devicesPhotodiodes, Phototransistors, Charge coupled devices

((CCDsCCDs),), PyroelectricPyroelectric sensors, Integrated optics.sensors, Integrated optics.

Magnetic sensorsMagnetic sensors

Chemical sensors & biosensorsChemical sensors & biosensors

--ISFET sensors, EnzymeISFET sensors, Enzyme--based biosensors, Microelectrodesbased biosensors, Microelectrodes

for neurophysiology.for neurophysiology.

Mechanical sensorsMechanical sensors

--PiezoresistorsPiezoresistors , Piezoelectric sensors, Capacitive sensors,, Piezoelectric sensors, Capacitive sensors,Optical sensors, Resonant sensors, Accelerometers,Optical sensors, Resonant sensors, Accelerometers,

Pressure sensors.Pressure sensors.

http://http://www.dbanks.demon.co.uk/uengwww.dbanks.demon.co.uk/ueng//


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MicroactuatorMicroactuatorof Classificationof Classification

Electrostatic actuatorsElectrostatic actuators

--Comb Drives, WobbleComb Drives, Wobblemotorsmotors

Magnetic actuatorsMagnetic actuators

Piezoelectric actuatorsPiezoelectric actuators

Thermal actuatorsThermal actuators

Hydraulic actuatorsHydraulic actuators

MicrostimulatorsMicrostimulators

http://www.dbanks.demon.co.uk/ueng/


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Micro Flow SensorsMicro Flow Sensors


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Micro Cooling SystemsMicro Cooling Systems


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IC ProcessesIC Processes

OxidationOxidationDiffusionDiffusion

LPCVDLPCVD

PhotolithPhotolith

EpitaxyEpitaxySputteringSputtering

etcetc

MicromachiningMicromachining

ProcessesProcesses

Bulk MicromachiningBulk Micromachining

Surface MicromachiningSurface Micromachining

Wafer BondingWafer Bonding

Deep Silicon RIEDeep Silicon RIE

LIGALIGA

MicromoldingMicromoldingetcetc

MEMs ProcessesMEMs Processes

MEMs

S C S


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Silicon Crystal StructureSilicon Crystal Structure


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MicrofabricationMicrofabrication ProcessesProcesses

IC F b i tiIC F b i ti


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PVDLPCVDCVD

IC FabricationIC Fabrication

,.

,,..

,...

T i l f id ti fT i l f id ti f


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Typical wafer oxidation furnaceTypical wafer oxidation furnace

* Thermal oxidation is a high temperature process.

* Used to grow a continuous layer of high-quality.

* Silicon dioxide on silicon substrate.

Dry OxidationOxidation species is oxygen.

Wet Oxidation

Oxidation species is watervapour.

http://www.memsnet.org/

f


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The spin casting process as used forThe spin casting process as used for

photoresistphotoresist in photolithographyin photolithography


Typical Etching (wet etching)Typical Etching (wet etching)


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Typical Etching (wet etching)Typical Etching (wet etching)

Wet Etching

This covers any form of etching where etching is

performed by immersing the wafer in a bath of the

chemical etchant. The chemical etchants can be split

into two types, isotropic and anisotropic. Isotropic

etchants will etch a given material at the same rate

what ever direction it is etching in, by

contrast anisotropic etchants will etch

at different rates in a given material

depending on a number of factors,

the most useful one being the crystalstructure and orientation.

Bulk Micromachining

http://www.tronics-mst.com

anisotropic etching

AnisotropicIsotropic

http://www.el.utwente.nl


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Thin Film DepositionThin Film Deposition


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Chemical VapourDeposition (CVD) ProcessCVD is capable of producing thick, dense, ductile, and good adhesive

coatings on metals and non-metals such as glass and plastic.Contrasting to the PVD coating in the "line of sight", the CVD can coat

all surfaces of the substrate.

- APCVD,LPCVD, PECVD. MOCVD

Physical VapourDeposition (PVD) ProcessPVD coatings involve atom-by-atom, molecule-by-molecule, or ion

deposition of various materials on solid substrates in vacuum systems.

- Thermal evaporation, Sputtering

Thin Film DepositionThin Film Deposition

Typical CVD systemTypical CVD system


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Processes

APCVD Atmospheric pressure CVD

LPCVD Low pressure CVD

PECVD Plasma enhanced CVD

Reaction Types

Heterogeneous reaction

- Chemical reaction takes place

- Very close to the surface

- Good quality films

Homogeneous reaction

- Chemical reaction takes place

- In the gas phase

- Poor quality films

Reaction Energy

Thermal

Photons

Electrons

Typical CVD systemTypical CVD system

Typical hotTypical hot--wall LPCVD reactorwall LPCVD reactor


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Typical hotTypical hot--wall LPCVD reactorwall LPCVD reactor

Reaction rate limited operation

Operates at 0.1 to 1Torr pressure

Good quality films

Conformal coverage

Typically used for HTO, PolySi,

Some metal films and nitridehttp://www.memsnet.org/

Typical system for eTypical system for e--beam evaporation ofbeam evaporation of


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yp yyp y pp

materialsmaterials

Provides very clean andhigh purity metal films


Typical coldTypical cold wall vapor phasewall vapor phase epitaxialepitaxial reactorreactor


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Typical coldTypical cold--wall vapor phasewall vapor phase epitaxialepitaxial reactorreactor

The same crystallographicorientation.An amorphous/polycrystallinesubstrate.The films of thick


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Typical RF,DC sputtering systemTypical RF,DC sputtering system

DC Sputtering -DC voltage between target and substrate,

used for conductive targets (metal films)

RF Sputtering -RF voltage between target and substrate,

used for insulators (dielectrics)

Magnetron Sputtering - Magnetic field confines electrons near the target,

increasing the number of electrons causing,

ionization collisions and, thereby, deposition rates,

Reactive Sputtering - Sputtering a target material in presence of a

reactive gas, thereby, depositing a compound.


Micromachining ProcessesMicromachining Processes


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Micromachining ProcessesMicromachining Processes

LIGA

SurfaceMicromachining

Bulk

Micromachining


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Surface MicromachiningSurface Micromachining


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gg

Two kinds of Surface MicromachiningTwo kinds of Surface Micromachining


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gg

SimpleSimple MicromirrorMicromirrorFabricationFabrication


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pp

SandiaSandia UltraUltra--planar Multiplanar Multi--level MEMSlevel MEMS

T h l (T h l (SUMMiTSUMMiT ))


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An electrostatic microengine output gear

coupled to a double-level gear train that

drives a rack and pinion slider. This gear

train provides a speed-reduction/torque-

multiplication ratio of 9.6 to 1.

A pin-in-maze microcombination lock. Thepin must be electrostatically deflected to

traverse the maze cut into the large gear.

Technology (Technology (SUMMiTSUMMiT ))


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LIGALIGA ((LithographieLithographie,, GalvanoformungGalvanoformung,, AbformungAbformung)) FabricationFabrication


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LIGA ((Lithographieg p ,, Galvanoformungg,,Abformungg)) Fabrication

90,

SummarySummary


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(MEMS

CAD)

ReferencesReferences


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http://www.dbanks.demon.co.uk/ueng/


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Questions or Comments

Thanks you !

Documents

(1)Introduction of MEMs