ISE 316: Manufacturing Engineering I: Processes

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) http://www.pbs.org/transistor/science/events/pointctrans.html 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 300000 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. Nano-abacus of C60 molecules A C60 molecule http://jcrystal.com/steffenweber/POLYHEDRA/p_00.html

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 carbonmolecules 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” www.foresight.org/EOC/Engines.pdf 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 http://www.photon.t.u-tokyo.ac.jp/~maruyama/wrapping.files/frame.html 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

20. Reasons to Miniaturize

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 Systems W

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 differentproteins 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 differentproteins found in human blood serum.

45. Sensors: Mechanical Measurement Atomic Force Microscope

46. Accelerometers 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.