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Shivaprasad K. Tilekar

Associate Professor

VLSI Design & Research Centre, Post Graduate Department of ElectronicsShankarrao Mohite Mahavidyalaya, Akluj, Dist. Solapur (MS)

Corresponding author: t_shivaprasad@rediffmail.com

Dedicated to my guide

B. P. LadgaonkarProfessor & Head

Post graduate Department of ElectronicsShankarrao Mohite Mahavidyalaya, Akluj, Dist. Solapur (MS)

MicroElectroMechnical Systems(MEMS)

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Historical ApproachRichard Feynman "There's Plenty of Room at the Bottom”- Presentation given December 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 FET" in 1969- microelectronics fabrication techniques-Invention of surface micromachining & use of sacrificial material to freemicromechanical devices from the silicon substrate.

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

Early experiments in surface-micromachined polysilicon in 1980’s- First electrostatic comb drive actuators- micropositioning disc drive heads

Micromachining leverages microelectronics industry in late 1980’s- Widespread experimentation and documentation increases public interest

Kurt Petersen published -Silicon as a Structural (Mechanical) Material in 1982- Reference for material properties and etching data for silicon

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a. Richard Feynman viewing the micromotor built by William McLellanb. Photograph of the motor 3.81 mm wide sitting beneath the head of pin

Feynman Challenge

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Production Engineering

Origin

Mechatronics Engineering• Micromechatronics• Nanomechatronics

Manufacturing Engineering

Micromanufacturing Engineering

• Microelectronics• MEMS

Nanomanufacturing Engineering

• Nanoelectronics• NEMS

Precision & Ultra precision Engineering

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Design, Fabrication & Testing

Scaling, Accuracy, Resolution and Repeatability

1. Micromilling : Cutting tool based & Focused Ion Based (FIB)

Spot size ~0.45um with 2.5 nA current and current density ~1.65 A/cm2

Typical milling rate 0.65um3/nA S. Average yield 6.5 atoms/ion.

2. Microdrilling:

Available 0.03-0.50 mm with increment of 0.01 mm.

Ultra Fast Pulse Laser Interface (PIL) technique

1. Si wafer- T: 0.54mm, Hole Diameter: 25um and Pitch: 50um

2. Al Niytide substrate T: 425um, Hole Diameter: ~290-300um

Precision Engineering Process

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Scaling

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Microlevel Scaling Issues

1. Friction is greater than inertia. Capillary, electrostatic and atomic forces as well

as stiction at a micro-level can be significant.

2. Heat dissipation is greater than heat storage and consequently thermal transport

properties could be a problem or, conversely, a great benefit.

3. Fluidic or mass transport properties are extremely important. Tiny flow spaces

may blockages or conversely may regulate fluid movement.

4. Material properties (Young’s modulus, Poisson’s ratio, etc.) and mechanical

theory (residual stress, wear, etc.) may be size dependent.

5. Integration with on-chip circuitry is complex and device/domain specific.

6. Miniature device packaging and testing is not straightforward.

7. Inexpensive – for the success of a MEMS device, it needs to leverage its IC batch

fabrication resources and be mass-produced.

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Importance of MST

• Minimize energy and materials use in manufacturing

• Redundancy and arrays

• Integration with electronics

• Reduction of power budget

• Faster devices

• Increased selectivity and sensitivity

• Exploitation of new effects through the breakdown of continuum theory

in the micro-domain

• Cost/performance advantages

• Improved reproducibility (batch fabrication)

• Improved accuracy and reliability

• Minimally invasive (e.g. pill camera)

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Classification of MST

Opt

ics

Electronics

MOES

MOEMS

MOMS MEMS

Mechanics

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Definition of MEMS

Micro - Small size, microfabricated structures

Electro - Electrical signal /control

Mechanical - Mechanical functionality

Systems - Structures, Devices, Systems- Control

The creation of 3-dimensional structures using integrated

circuits fabrication technologies and special micromachining processes.

Interdisciplinary Approach: IC Fabrication Technology, Mechanical

Engineering, Materials Science, Electrical Engineering, Chemistry and

Chemical Engineering, Fluid Engineering, Optics, Instrumentation and

Packaging.

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MEMS Devices

SemiconductorsInsulatorsDiodesTransistors

MEMS

ConductorsResistorsCapacitorsInductors

GearBearingDiaphragmPlatesCantileversBeamPostAnchorProbe etc.

Electronics, Electrical and Mechanical at MICRO LEVEL

Passive Electronic Systems & Passive Mechanical Systems

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MEMS Devices

MEMS

Microelectronics

MicrosensorsMicroactuators

Mechanical Microstructures

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Traditional Embedded Systems

Op amp

LP filter A/D Microcontroller

Op ampD/A

Sensor

Digital Outputs

LEDs

Competitive Solutions

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Recent Trend Embedded System

Op amp

LP filter A/D Microcontroller D/A

Sensor

Digital Outputs

LEDs

PSoC Microcontrollers

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Integrated embedded Microsystem

SensorElectronic

CircuitActuator

Micro Level

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MEMS Sensors

Based on Principles1. Thermoelectric2. Photoelectric3. Electromagnetic4. Magnetoelectric5. Thermoelastic6. Pyroelectric7. Thermomagnetic

Important Attributes1. Stimulus2. Specifications3. Physical Phenomenon4. Conversion Mechanism5. Material6. Response7. Ruggedness8. Stiffness9. Range10.Ability to measure parameters11. Application field

Measurable Parameters1. Temperature2. Pressure3. Humidity4. Flow5. Light Intensity6. Magnetic Field7. Vibration & so on

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MEMS in Automobile

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MEMS in BioMedical

Geographic ulceration suggestive of Barret'sEsophagus.

Pill Camera

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MEMS Actuators

Method Principle Power

Voltage

Current

Speed

Mechanical

Piezoelectric High 10-100 V

nA-uA mS

Thermal Galvanic High 1-10 V mA-10mA

mS

Electrostatic

Electrostatic Coulomb

Low 10-100 V

nA-uA uS

Magnetic Current Medium

1-5 V ~ 100mA

uS-mSInterfacing Components• Gear• Bearing• Diaphragm• Plates• Cantilevers• Beam• Post• Anchor• Probe etc.

On Movement• Translational• Rotational

Important Attributes1. Lightweight2. Conformable3. Precision4. Less Wear & Sticking

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Microelectronics

Deposition Chemical vapor deposition (CVD) Epitaxy Oxidation Evaporation Sputtering Spin-on methods

Etching Wet chemical etching

Istropic Anisotropic

Dry etching Plasma etch Reactive Ion etch (RIE, DRIE)

Patterning Photolithography X-ray lithography

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Mechanical MicroStructure

General Classification1. Bulk Micromachining2. Surface Micromachining3. High-Aspect-Ratio Micromachining (HARM)

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MicroStructure Cont…

Photolithography

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MicroStructure Cont…

Substrate: Si, Ge and GaAs

a. Abundant, inexpensive, and processed to unparalleled purity

b. Ability to be deposited in thin films is very amenable to MEMS

c. High definition and reproduction (high levels of MEMS precision)

d. Batch fabrication

Additive Films & Materials

a. Silicon - single crystal, polycrystalline and amorphous

b. Silicon compounds (SixNy, SiO2, SiC etc.)

c. Metals and metallic compounds (Au, Cu, Al, ZnO, GaAs, IrOx, CdS)

d. Ceramics (Al203 and more complex ceramic compounds)

e. Organics (diamond, polymers, enzymes, antibodies, DNA etc.)

Materials for Micromachining

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MicroStructure Cont…

Bulk Micromachining

Wet Etching (Liquid Phase) Substrate: Si or Quartz

To create large pits, grooves & channelsIsotropic Anisotropic(HNA) (KOH)

With agitation

Without agitation

MicroStructure Cont…

Bulk Micromachining

SiO2

p+ Si

<100> Sisubstrate

Pressure sensors

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MicroStructure Cont…

Bulk Micromachining

Dry Etching (Vapour Phase or Plasma-Based)

Substrate: Si, Plastic, Metal Ceramics

To create deep trenches & pits

Reactive Ion Etching

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MicroStructure Cont…

Surface MicromachiningDry Etching (Vapour Phase or Plasma-Based)

To create foundation layers

Reactive Ion Etching, Multi-User MEMS Procces (MUMP), Sandia Ultra

Planner Multi level Technology

Polysilicon micromotor Polysilicon resonator structure

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MicroStructure Cont…

Surface Micromachining

Fusion Bonding

Photoresist and PolyMethylMethAcrylate (PMMA)

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MicroStructure Cont…

High-Aspect Ratio Micromachining

Deep Reactive Ion Etching (DRIE)

Si

Glass

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MicroStructure Cont…

High-Aspect Ratio Micromachining

LIGA (a German acronym from Lithographie, Galvanoformung, Abformung translated as lithography, electroforming and moulding)

Other Technologies for HARMHot EmbossingLaser MicromachiningXeF2 Dry Phase EtchingElectro-Discharge MicromachiningFocused Ion Beam MicromachiningCAD Tool (MEMCAD)

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Assembly & System Integration

CAD design using MEMCAD from various vendors

Mask Generator

CAD Simulation & Modeling

Original Concept

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Applications

Controlling Micromanipulator, Microhandling Equipments, Microgrippers, Microrobots, etc.

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MEMS Market Forecast

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Challenges to MEMSIndustry

Access to Foundry

Design, Simulation and Moldelling

Packaging and Testing

Standardization

Education and Training

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MEMS Resources

Books

1. MEMS – N. P. Mahalik

2. Scaling Issues and Design of MEMS- S. Baglio, S. Castorina & N. Savalli

Websites

3. www.engineersgarage.com/articles/mems-technology

4. www.egr.msu.edu/classes/ece410/mason/files/MEMS%20overview.pdf

5. www.csa.com/discoveryguides/mems/overview.php

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Research Activities

Minor Research Projects : 01 Completed

(UGC Sponsored) : 01 OngoingPublications

: International Journals 05: National Journals 01: Proceedings International/National15

Papers presented in conferences: International 04: International (Abroad)01: National 46

Academic Talk : 06

THANK YOU