Overview of MEMS and Microsystems
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Transcript of Overview of MEMS and Microsystems
Lectures onMEMS and MICROSYSTEMS DESIGN
AND MANUFACTURE
Tai-Ran Hsu, ASME Fellow, ProfessorMicrosystems Design and Packaging Laboratory
Department of Mechanical and Aerospace EngineeringSan Jose State UniversitySan Jose, California, USAE-mail: [email protected]
CONTENT
Chapter 1 Overview of MEMS and Microsystems
Chapter 2 Working Principles of Microsystems
Chapter 3 Engineering Science for Microsystems Design and Fabrications
Chapter 4 Engineering Mechanics for Microsystems Design
Chapter 5 Thermofluid Engineering and Microsystems Design
Chapter 6 Scaling Laws in Miniaturization
Chapter 7 Materials for MEMS and Microsystems
Textbook: “MEMS and Microsystems: design , manufacture, and nanoscale engineering,”2nd Edition, by Tai-Ran Hsu, John Wiley & Sons, Inc., Hoboken, New Jersey, 2008(ISBN 978-0-470-08301-7)
Chapter 8 Microsystems Fabrication Processes
Chapter 9 Overview of Micromanufacturing
Chapter 10 Microsystems Design
Chapter 11 Assembly, Packaging, and Testing of Microsystems
Chapter 12 Introduction to Nanoscale Engineering
CONTENT –Cont’d
Chapter 1
Overview of MEMS and Microsystems
Hsu 2008
WHAT IS MEMS?MEMS = MicroElectroMechanical System
Any engineering system that performs electrical and mechanical functions with components in micrometers is a MEMS. (1 µm = 1/10 of human hair)
Available MEMS products include:
● Micro sensors (acoustic wave, biomedical, chemical, inertia, optical, pressure, radiation, thermal, etc.)
● Micro actuators (valves, pumps and microfluidics; electrical and optical relays and switches;grippers, tweezers and tongs; linear and rotary motors, etc.)
● Read/write heads in computer storage systems.● Inkjet printer heads.● Micro device components (e.g., palm-top reconnaissance aircrafts, mini
robots and toys, micro surgical and mobile telecom equipment, etc.)
HOW SMALL ARE MEMS DEVICES?
in plain English please!They can be of the size of a rice grain, or smaller!
Two examples:
- Inertia sensors for air bag deployment systems in automobiles
- Microcars
Inertia Sensor for Automobile “Air Bag” Deployment System
Micro inertia sensor (accelerometer) in place:
(Courtesy of Analog Devices, Inc)
Sensor-on-a-chip:(the size of a
rice grain)
Micro Cars(Courtesy of Denso Research Laboratories, Denso Corporation, Aichi, Japan)
Rice grains
MEMS = a pioneer technology for Miniaturization –
A leading technology for the 21st Century, and
an inevitable trend in industrial products and systems development
Miniaturization of Digital Computers- A remarkable case of miniaturization!
The ENIAC Computer in 1946 A “Lap-top” Computer in 1996
A “Palm-top” Computer in 2001
Size: 106 downPower: 106 up
Size: 108 downPower: 108 up
This spectacular miniaturization took place in 50 years!!
MINIATURIAZATION – The Principal Driving Force for the 21st Century Industrial Technology
There has been increasing strong market demand for:
“Intelligent,”
“Robust,”
“Multi-functional,” and
“Low-cost” industrial products.
Miniaturization is the only viable solution to satisfy such market demand
Market Demand for Intelligent, Robusting, Smaller, Multi-Functional Products - the evolution of cellular phones
Mobil phones 10 Years Ago: Current State-of-the Art:
Transceive voice only
Transceive voice+ multi-media + others (Video-camera, e-mails, calendar, and access to Internet, GPS and a PC with key pad input)
Size reduction
Palm-top Wireless PC
The only solution is to pack many miniature function components into the device
Miniaturization Makes Engineering Sense!!!
• Small systems tend to move or stop more quickly due to low mechanical inertia.It is thus ideal for precision movements and for rapid actuation.
• Miniaturized systems encounter less thermal distortion and mechanical vibration due to low mass.
• Miniaturized devices are particularly suited for biomedical and aerospace applications due to their minute sizes and weight.
• Small systems have higher dimensional stability at high temperature due tolow thermal expansion.
• Smaller size of the systems means less space requirements. This allows the packaging of more functional components in a single device.
• Less material requirements mean low cost of production and transportation.
• Ready mass production in batches.
Enabling Technologies for Miniaturization
Miniature devices(1 nm - 1 mm)
** 1 nm = 10-9 m ≈ span of 10 H2 atoms
Microsystems Technology(MST)
(1 µm - 1 mm)* Initiated in 1947 with the invention of transistors, but the term “Micromachining”was coined in 1982
* 1 µm = 10-6 m ≈ one-tenth of human hair
Nanotechnology (NT)(0.1 nm – 0. 1 µm)**
Inspired by Richard Feynman in 1959, with active R&D began in around 1995There is a long way to building nano devices!
A top-down approach
A bottom-up approach
The Lucrative Revenue Prospects for Miniaturized Industrial Products
Microsystems technology:$43 billion - $132 billion* by Year 2005( *High revenue projection is based on different definitions
used for MST products)
Source: NEXUS http://www.smalltimes.com/document_display.cfm?document_id=3424
Nanotechnology:$50 million in Year 2001$26.5 billion in Year 2003(if include products involving parts produced by nanotechnology)
$1 trillion by Year 2015 (US National Science Foundation)
An enormous opportunity for manufacturing industry!!
● There has been colossal amount of research funding to NT by governments of industrialized countries around the world b/cof this enormous potential.
The Lucrative Revenue Prospects for Miniaturized Industrial Products – Cont’d
MEMS Products
MicroSensingElement
InputSignal
TransductionUnit
OutputSignal
PowerSupply
MEMS as a Microsensor:
Micro pressure sensors
MicroActuatingElement
OutputAction
TransductionUnit
PowerSupply
MEMS as a Microactuator- motor:
Micro motor produced by a LIGA Process
Stators
RotorTorque
TransmissionGear
Components of Microsystems
Sensor
Signal Transduction &
ProcessingUnit
Actuator
PowerSupply
Microsystem
Typical Microsystems Products
Inertia Sensor for “Air Bag” Deployment System(Courtesy of Analog Devices, Inc.)
Inertia Sensor for Automobile “Air Bag” Deployment System
Micro inertia sensor (accelerometer) in place:
(Courtesy of Analog Devices, Inc)
Sensor-on-a-chip:(the size of a
rice grain)
Collision
Unique Features of MEMS and Microsystems - A great challenge to engineers
• Components are in micrometers with complex geometryusing silicon, si-compounds and polymers:
25 µm
25 µm
A micro gear-train bySandia National Laboratories
Capillary Electrophoresis (CE) Network Systems for Biomedic Analysis
A simple capillary tubular network with cross-sectional area of 20x30 µm is illustrated below:
AnalyteReservoir,A
Analyte WasteReservoir,A’
BufferReservoir,B
WasteReservoir,B’
Injection Channel
Sepa
ratio
n C
hann
el
Silicon Substrate
“Plug”
Work on the principle of driving capillary fluid flow by applying electric voltages at the terminals at the reservoirs.
Commercial MEMS and Microsystems Products
Micro Sensors:
Acoustic wave sensorsBiomedical and biosensorsChemical sensorsOptical sensorsPressure sensorsStress sensorsThermal sensors
Micro Actuators:
Grippers, tweezers and tongsMotors - linear and rotaryRelays and switchesValves and pumpsOptical equipment (switches, lenses & mirrors, shutters, phase modulators, filters, waveguide splitters, latching & fiber alignment mechanisms)
Microsystems = sensors + actuators + signal transduction:
• Microfluidics, e.g. Capillary Electrophoresis (CE)• Microaccelerometers (inertia sensors)
INPUT:Desired
Measurements or
functions
Sensing and/oractuatingelement
Transductionunit Signal
Conditioner& Processor
Controller Actuator
SignalProcessor
MeasurementsComparator
OUTPUT:Measurements
or Actions
MEMS
Package on a single “Chip”
Intelligent Microsystems - Micromechatronics systems
Evolution of Microfabrication
● There is no machine tool with today’s technology can produce any device or MEMS component of the size in the micrometer scale (or in mm sizes).
● The complex geometry of these minute MEMS components can only be produced by various physical-chemical processes – the microfabrication techniques originallydeveloped for producing integrated circuit (IC) components.
Significant technological development towards miniaturization was initiated with the invention of transistors by three Nobel Laureates, W.Schockley, J. Bardeen and W.H. Brattain of Bell Laboratories in 1947.
This crucial invention led to the development of the concept of integrated circuits (IC) in 1955, and the production of the first IC three years later by Jack Kilby of Texas Instruments.
ICs have made possible for miniaturization of many devices and engineering systems in the last 50 years.
The invention of transistors is thus regarded as the beginning of the 3rd Industrial Revolution in human civilization.
Comparison of Microelectronics and MicrosystemsMicroelectronics Microsystems (silicon based)
Primarily 2-dimensional structures Complex 3-dimensional structureStationary structures May involve moving componentsTransmit electricity for specific electrical functions Perform a great variety of specific biological, chemical,
electromechanical and optical functionsIC die is protected from contacting media Delicate components are interfaced with working mediaUse single crystal silicon dies, silicon compounds,ceramics and plastic materials
Use single crystal silicon dies and few other materials,e.g. GaAs, quartz, polymers, ceramics and metals
Fewer components to be assembled Many more components to be assembledMature IC design methodologies Lack of engineering design methodology and standardsComplex patterns with high density of electricalcircuitry over substrates
Simpler patterns over substrates with simpler electricalcircuitry
Large number of electrical feed-through and leads Fewer electrical feed-through and leadsIndustrial standards available No industrial standard to follow in design, material
selections, fabrication processes and packagingMass production Batch production, or on customer-need basisFabrication techniques are proven and welldocumented
Many microfabrication techniques are used forproduction, but with no standard procedures
Manufacturing techniques are proven and welldocumented
Distinct manufacturing techniques
Packaging technology is relatively well established Packaging technology is at the infant stagePrimarily involves electrical and chemicalengineering
Involves all disciplines of science and engineering
Natural Science:Physics & Biochemistry
Mechanical Engineering• Machine components design• Precision machine design• Mechanisms & linkages• Thermomechanicas:
(solid & fluid mechanics, heattransfer, fracture mechanics)
• Intelligent control• Micro process equipment
design and manufacturing• Packaging and assembly design
Quantum physicsSolid-state physicsScaling laws
Electrical Engineering• Power supply• Electric systems for
electrohydro-dynamics and signal transduction
• Electric circuit design
•Integration of MEMSand CMOS
Materials Engineering• Materials for substrates
& package• Materials for signal
mapping and transduction• Materials for fabrication
processes
Chemical Engineering• Micro fabrication
processes• Thin film technology
Industrial Engineering• Process design• Production control• Micro assembly
ElectrochemicalProcesses
MaterialScience
The Multi-disciplinary Nature of Microsystems Engineering
Commercialization of MEMS and Microsystems
Major commercial success:
Pressure sensors and inertia sensors (accelerometers) with worldwide market of:
• Airbag inertia sensors at 2 billion units per year.• Manifold absolute pressure sensors at 40 million units per year.• Disposable blood pressure sensors at 20 million units per year.
Recent Market DynamicsOld MEMS New MEMS
Pressure sensorsAccelerometersOther MEMS
BioMEMSIT MEMS for Telecommunication:(OptoMEMS and RF MEMS)
Application of MEMS and Microsystemsin
Automotive Industry
52 million vehicles produced worldwide in 1996There will be 65 million vehicle produced in 2005
Principal areas of application of MEMS and microsystems:
• Safety• Engine and power train
• Comfort and convenience• Vehicle diagnostics and health monitoring
• Telematics, e.g. GPS, etc.
(1)(7)
(10)(2)
(3)(4)
(5)
(6)
(8)(9)
(2) Exhaust gas differential pressure sensor
(1) Manifold or Temperature manifold absolute pressure sensor
(3) Fuel rail pressure sensor(4) Barometric absolute pressure sensor(5) Combustion sensor
(7) Fuel tank evaporative fuel pressure sensor
(6) Gasoline direct injection pressure sensor
(8) Engine oil sensor
(9) Transmission sensor
(10) Tire pressure sensor
Principal Sensors
Silicon Capacitive Manifold Absolute Pressure Sensor
Application of MEMS and Microsystemsin
Aerospace Industry
• Cockpit instrumentation. • Sensors and actuators for safety - e.g. seat ejection• Wind tunnel instrumentation • Sensors for fuel efficiency and safety• Microsattellites• Command and control systems with MEMtronics• Inertial guidance systems with microgyroscopes, accelerometers and fiber optic gyroscope.• Attitude determination and control systems with micro sun and Earth sensors.• Power systems with MEMtronic switches for active solar cell array reconfiguration, and
electric generators• Propulsion systems with micro pressure sensors, chemical sensors for leak detection, arrays
of single-shot thrustors, continuous microthrusters and pulsed microthrousters• Thermal control systems with micro heat pipes, radiators and thermal switches• Communications and radar systems with very high bandwidth, low-resistance radio-frequency
switches, micromirrors and optics for laser communications, and micro variable capacitors, inductors and oscillators.
Application of MEMS and Microsystemsin
Biomedical Industry
Disposable blood pressure transducers:Lifetime 24 to 72 hours; annual production 20 million units/year, unit price $10
Catheter tip pressure sensors
Sphygmomanometers
Respirators
Lung capacity meters
Barometric correction instrumentation
Medical process monitoring
Kidney dialysis equipment
Micro bio-analytic systems: bio-chips, capillary electrophoresis, etc.
Application of MEMS and Microsystemsin
Consumer Products
Scuba diving watches and computers
Bicycle computers
Sensors for fitness gears
Washers with water level controls
Sport shoes with automatic cushioning control
Digital tire pressure gages
Vacuum cleaning with automatic adjustment of brush beaters
Smart toys
Application of MEMS and Microsystemsin the
Telecommunication Industry
• Optical switching and fiber optic couplings
• RF relays and switches
• Tunable resonatorsMicrolenses: Microswitches:
Projected Market for OptoMEMS
Unit: $million
Micro Optical Switches
2-Dimensional
3-Dimensional
Concluding Remarks
1. Miniaturization of machines and devices is an inevitable trend in technological development in the new century.
2. There is a clear trend that microsystems technology will be further scaled down to the nano level. (1 nm = 10-3 µm = 10 shoulder-to-shoulder H2 atoms).
3. Despite the fact that many microelectronics technologies can be used to fabricate silicon-based MEMS components, microsystems engineering requires the application of principles involving multi-disciplines in science and engineering.
4. Team effort involving multi-discipline of science and engineering is the key to success for any MEMS industry.
End of Chapter 1