ise 316: manufacturing engineering i: processes

ISE 316: Manufacturing Engineering I: Processes

Micro/Nano-Scale Manufacturing

Outline

• Historical Perspective and Introduction

• Why make things very small

• Sensors and Actuators

• Micro/nano-scale manufacturing processes

If at first, the idea is not absurd, then there is no hope for it.

- Albert Einstein

MEMS & Nanotechnology: A Glimpse

1822: Nicéphore Niépce invents lithography to pattern a portrait. Five years later, Lemaître etched out the engraving with a strong acid

1939: First p-n junction on a semiconductor (W. Schottky)

1958: First integrated circuit developed at Texas Instruments. Jack Kilby wins the Nobel at 2000

1959: Richard Feynman dreams big (Oops, small!)

Cardinal d’Amboise

First IC

1948: First transistor (J. Bardeen, W.H. Brattain, W. Shockley) http://www.pbs.org/transistor/science/events/pointctrans.html

Why can’t we write the entire 24 volumes of Encyclopedia Brittanica on the head of a pin?


1965: Gordon Moore foretells the future of silicon industry

1965: First MEMS device? Resonant gate transistor built by Nathanson, Newell and Wickstrom

Every 2 years: # transistors double; cost remains same or decreases. On the same scale in the auto industry, cars would cost 5 cents and average 300000 mpg today

•Human hair: 50,000 nm across

•Viruses range in size from 20 to 300 nanometers (nm)

•10 hydrogen atoms in a line, 10 Angstroms (or 1 nm)

A View from Macro to Micro to Nano

Nanoparticles exist all around us – in sea, air, cigarette smoke, and diesel exhaust.

So, what is different today?

Why is the issue of nanotechnology generating so much discussion?


1989: Breakthrough in MEMS. Polysilicon micromotors built by Tai and Muller. Lateral comb drive actuator built by Tang, Nguyen and Howe

hair

RotorStator

combs

1994: Digital micro-mirror device (DMD) from Texas Instruments

1995: Commercial accelerometer from Analogue Devices


IC vs MEMS Technology

AMD K6 Microprocessor(top 6 layers only)

0.75

TI - DMD


Is there a limit?

What are the issues?Fabrication (180 nm)MaterialsPhysical mechanisms


1985: R. Smalley, R. Curl and H. Kroto discovers Buckminsterfullerene or Bucky ball. Nobel in 1996.

Nano-abacus of C60 molecules

http://jcrystal.com/steffenweber/POLYHEDRA/p_00.html

A C60 molecule

Nano materials

• Carbon nanotubes (CNTs; also known as buckytubes) are allotropes of carbon with a cylindrical nanostructure. Nanotubes have been constructed with length-to-diameter ratio of up to 132,000,000:1,[1] significantly larger than any other material. These cylindrical carbon molecules have novel properties, making them potentially useful in many applications in nanotechnology, electronics, optics, and other fields of materials science, as well as potential uses in architectural fields.

http://en.wikipedia.org/wiki/Allotropes_of_carbon

http://en.wikipedia.org/wiki/Carbon

http://en.wikipedia.org/wiki/Molecule

http://en.wikipedia.org/wiki/Chemical_property

Armchair and zigzagcarbon nanotube

Multiwall nanotubes


1986: (1) Atomic Force Microscope is invented.

(2) Eric Drexler publishes “Engines of Creation” www.foresight.org/EOC/Engines.pdf

NaCl on Mica

During the early decades of the 21st century, the advent of practical molecularmanufacturing technology will make it possible to fabricate inexpensively almost any conceivable structure allowed by the laws of physics.

Consequences will include immensely powerful computers, abundant and very high quality consumer goods, and microscopic devices able to cure most diseases by repairing the body from the molecular level up.


1991: Sumio Ijima discovers carbon nanotubes

http://www.photon.t.u-tokyo.ac.jp/~maruyama/wrapping.files/frame.html

1997: DNA based micromechanical device built


Nano gears

2001: Carbon nanotube based logic demonstrated

Nano bearings

Should we borrow from Nature?

NATURE vs. ENGINEERINGNATURE vs. ENGINEERING

Billions of years to evolveBillions of years to evolve Revolutionary, Ingenuity drivenRevolutionary, Ingenuity driven

Does not use metalsDoes not use metals Metals and Artificial materials Metals and Artificial materials drivendriven (e.g. Stone Age (e.g. Stone Age Iron Age) Iron Age)

Movement by sliding/contractionMovement by sliding/contraction The Wheel The Wheel

Energy storageEnergy storageGravitational/ ElasticGravitational/ Elastic Electrical and KineticElectrical and Kinetic

A wet technologyA wet technology Mostly dryMostly dry

Smooth shapesSmooth shapes Sharp corners, rectangularSharp corners, rectangular

Nanometer: A Different Perspective

• Human hair: 50,000 nm across

• Bacterial cell: a few hundred nanometers

• Seeable with unaided human eye: 10,000 nanometers

• 10 hydrogen atoms in a line

Reasons to Miniaturize

Miniaturization Attributes

Reasons

Low energy and little material consumed

Limited resources

Arrays of sensors Redundancy, wider dynamic range, increased selectivity through pattern recognition

Small Small is lower in cost, minimally invasive

Favorable scaling laws

Forces that scale with a low power become more prominent in the micro domain; if these are positive attributes then miniaturization favorable (e.g. surface tension becomes more important than gravity in a narrower capillary)

Reasons to Miniaturize

Miniaturization Attributes

Reasons

Batch and beyond batch techniques

Lowers cost

Disposable Helps to avoid contamination

Breakdown of macro laws in physics and chemistry

New physics and chemistry might be developed

Smaller building blocks

The smaller the building blocks, the more sophisticated the system that can be built

Need for Scaling

• As linear size decreases behavior changes.– Not well understood on

the nano-scale.– Scaling represents an

approximation to assist in understanding.

• Scaling helps to explain nature and can also be used to design devices.

Scaling

• If a system is reduced isomorphically in size (i.e. scaled down with all dimensions of the system decreased uniformly), the changes in length, area and volume ratios alter the relative influence of various physical effects.

• Sometimes these effect the operation in unexpected ways.

Is scaling different in the micro world?

Scaling of Length, Surface Area and Volume

• What happens as an object shrinks?– Area L2

– Volume L3

L

LL

Why Whales Swim Faster

L3

L2

22

2

1LAuCF DD

where CD: drag coefficient ρ: density of fluid A: largest projected area of the body u: velocity

Scaling of Mechanical SystemsW

Scaling of Mechanical Systems

13

2 L

L

L

mass

forceonaccelerati

In nano-mechanical systems accelerations are large.

01 ))(())(( LLLtimeonacceleratispeed

Lfrequencyscaletimesticcharacteri 1__

Speed is length scale invariant.

Actuators

• Electrical

• Electrostatic

• Magnetic

• Thermal

Electrostatic Motors

+-

+-

-

Polysilicon micromotor:

• Rotor sits atop a 0.5mm layer of polysilicon that acts as an electrostatic shield.

• Rotor, hub, stators formed from 1.5mm polysilicon.

• A 2.0mm polysilicon disk is attached to rotor.

Projection TV Technology

Mirror mechanism for DLP TV (Texas Instruments)

Use of electrostatic torque for mirror positioning.

Thermal Actuation

The current flow produces Joule heating that in turn imparts a large thermal stress on the device, concentrated in the long thin beam. The thermal expansion of the thin beam causes the device to bend at the short thin beam. The blade rotates in the plane of the substrate.

Piezoelectric ActuatorsRecall the piezoelectric effect:

Ideal Sensor

• Zero Mass: no additional mass, no thermal compensation (no latent heat energy stored), thermally equilibrate infinitely rapid, infinitely wide dynamic response.

• Zero physical size: Could be installed virtually anywhere, extreme spatial resolution by arrays.

• Zero energy.

Historically, most successful applications of MEMS techniques fall in the “Sensors” category.

MEMS Sensors are close. They offer high sensitivity, can be batch fabricated (low cost, high volume), some times wireless and are robust

Mechanical Sensing

• Micro-mechanical structures at heart of design process• Beams that act as springs• Experience force and/or displacement• Deform under force, pressure, flow, etc.• Measure deflection

• Deflection equations developed for macro-scale and assume:• Material properties do not change• No residual stresses

Silicon is generally used for micro-mechanical structures.

Concept

kxF

Sensor and Transducer

• Sensor: Converts force to displacement

• Sensitivity: 1/k• Transducer : Apply force to get displacement• k can be constant or varying with force

kFx /

Cantilever Beam

3/3 LEIk The left cantilever bends as the protein PSA binds to the antibody. The other cantilevers are exposed to different

proteins found in human blood serum.

Another View of Sensing

Displacement as a means of sensing!

Mechanical Sensing

• Micro-mechanical structures at heart of design process• Beams that act as springs• Experience force and/or displacement• Deform under force, pressure, flow, etc.• Measure deflection

• Deflection equations developed for macro-scale and assume:• Material properties do not change• No residual stresses

Silicon is generally used for micro-mechanical structures.

Concept

kxF

Sensor and Transducer

• Sensor: Converts force to displacement

• Sensitivity: 1/k• Transducer : Apply force to get displacement• k can be constant or varying with force

kFx /

Cantilever Beam

3/3 LEIk The left cantilever bends as the protein PSA binds to the antibody. The other cantilevers are exposed to different

proteins found in human blood serum.

Sensors: Mechanical Measurement

Atomic Force Microscope

Accelerometers

Applications: Inertial guidance system, airbags, vibration measurement

When the reference frame is accelerated, the acceleration is transferred to the proof mass through the spring. The stretching of the spring, which is measured by a position sensor (represented as a length scale in the figure), gives the acceleration when the proof mass is known.

Natural frequency

Damping coefficient

Accelerometers

Piezoelectric Sensing

Chemical Sensor

Biological Sensing

Diagram of interactions between target and probe molecules on cantilever beam. Specific biomolecular interactions between target and probe molecules alter the intermolecular nanomechanical interactionswithin a self-assembled monolayer on one side of a cantilever beam. This can produce a sufficiently large force to bend the cantilever beam and generate motion.

ise 316: manufacturing engineering i: processes

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