1. ISE 316: Manufacturing Engineering I: Processes
Micro/Nano-Scale Manufacturing

2. Outline Historical Perspective and Introduction
Why make things very small
Sensors and Actuators
Micro/nano-scale manufacturing processes

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

4. 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)
Cardinal d’Amboise
1948: First transistor (J. Bardeen, W.H. Brattain, W. Shockley)
1958: First integrated circuit developed at Texas Instruments. Jack Kilby wins the Nobel at 2000
First IC
1959: Richard Feynman dreams big (Oops, small!)
Why can’t we write the entire 24 volumes of Encyclopedia Brittanica on the head of a pin?

5. MEMS & Nanotechnology: A Glimpse
1965: First MEMS device? Resonant gate transistor built by Nathanson, Newell and Wickstrom
1965: Gordon Moore foretells the future of silicon industry
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 mpg today

6. A View from Macro to Micro to Nano
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)
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?

7. MEMS & Nanotechnology: A Glimpse
1989: Breakthrough in MEMS. Polysilicon micromotors built by Tai and Muller. Lateral comb drive actuator built by Tang, Nguyen and Howe
hair
combs
Stator
Rotor
1994: Digital micro-mirror device (DMD) from Texas Instruments
1995: Commercial accelerometer from Analogue Devices

8. MEMS & Nanotechnology: A Glimpse
IC vs MEMS Technology
0.75 m
TI - DMD
AMD K6 Microprocessor
(top 6 layers only)

9. MEMS & Nanotechnology: A Glimpse
Is there a limit?
What are the issues?
Fabrication (180 nm)
Materials
Physical mechanisms

10. MEMS & Nanotechnology: A Glimpse
1985: R. Smalley, R. Curl and H. Kroto discovers Buckminsterfullerene or Bucky ball. Nobel in 1996.
General belief and excitement over buckyballs lies in their sheer strength for use in building materials. There is considerable belief that in the 21st century buckyballs and buckytubes may replace silicon as the building blocks for future electronic devices in computers and communication devices. Buckytubes are also the strongest materials known and are already finding applications in composite materials, as surface coatings to improve wear resistance, and as components in scientific instruments. Buckyballs may find application in drug delivery systems.
Because fullerenes are very large graphitic systems, they can easily accommodate extra electrons. When you add three electrons to C60 you get ionic solids of the general formula A3C60, where A is any metal in Group I (lithium, sodium, potassium, rubidium, cesium). These materials are actually metals, and display sup erconductivity at somewhat low temperatures. Current research is aimed at getting the maximum superconducting temperature (or Tc) to higher values.
C60 is just the right size to fit into the activ e cavity of HIV Protease, an enzyme important to the activity of the virus which causes AIDS. Cramming a buckyball into the active cavity would deactivate the enzyme and kill the virus. Ways of getting the molecule to the enzyme are under investigation.
Nano-abacus of C60 molecules
A C60 molecule

11. 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.

12. Armchair and zigzagcarbon nanotube

13. Multiwall nanotubes

14. MEMS & Nanotechnology: A Glimpse
1986: (1) Atomic Force Microscope is invented.
(2) Eric Drexler publishes “Engines of Creation”
NaCl on Mica
During the early decades of the 21st century, the advent of practical molecular
manufacturing 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.

15. MEMS & Nanotechnology: A Glimpse
1991: Sumio Ijima discovers carbon nanotubes
1997: DNA based micromechanical device built

16. MEMS & Nanotechnology: A Glimpse
2001: Carbon nanotube based logic demonstrated
Nano bearings
Nano gears

17. Should we borrow from Nature?
NATURE vs ENGINEERING
Billions of years to evolve Revolutionary, Ingenuity driven
Does not use metals Metals and Artificial materials driven (e.g. Stone Age  Iron Age)
Movement by sliding/contraction The Wheel
Energy storage
Gravitational/ Elastic Electrical and Kinetic
A wet technology Mostly dry
Smooth shapes Sharp corners, rectangular

18. 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

19. 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)

20. 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

21. 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.

22. 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.

23. Is scaling different in the micro world?

24. Scaling of Length, Surface Area and Volume
What happens as an object shrinks?
Area  L2
Volume  L3 L L L

25. Why Whales Swim Faster L3 L2
where CD: drag coefficient ρ: density of fluid A: largest projected area of the body u: velocity

26. Scaling of Mechanical SystemsW

27. Scaling of Mechanical Systems
In nano-mechanical systems accelerations are large.
Speed is length scale invariant.

28. Actuators
Electrical
Electrostatic
Magnetic
Thermal

29. 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.

30. Projection TV Technology

31. Use of electrostatic torque for mirror positioning.
Mirror mechanism for DLP TV (Texas Instruments)

32. 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.

33. Piezoelectric Actuators
Recall the piezoelectric effect:

34. 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

36. 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.

37. Concept

38. 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

39. Cantilever Beam
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.

40. Another View of Sensing
Displacement as a means of sensing!

41. 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.

42. Concept

43. 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

44. Cantilever Beam
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.

45. Sensors: Mechanical Measurement
Atomic Force Microscope

46. Accelerometers Natural frequency Damping coefficient
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
Applications: Inertial guidance system, airbags, vibration measurement
Damping coefficient

47. Accelerometers

48. Piezoelectric Sensing

49. Chemical Sensor

50. 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 interactions
within 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.