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Why do we put the micro in microelectronics?

Why do we put the micro in microelectronics?. Why Micro?. Lower Energy and Resources for Fabrication Large Arrays Minimally Invasive Disposable Smaller Time Scales Lower Cost What about the Physics?. Scaling at the Microscale. Not all properties scale in the same way!. Volume Forces

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Why do we put the micro in microelectronics?

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  1. Why do we put the micro in microelectronics?

  2. Why Micro? • Lower Energy and Resources for Fabrication • Large Arrays • Minimally Invasive • Disposable • Smaller Time Scales • Lower Cost What about the Physics?

  3. Scaling at the Microscale Not all properties scale in the same way! Volume Forces Gravity Inertia Mass Surface Forces Surface Tension Viscosity Heat Loss

  4. Animal Kingdom Larger Animals Limited number Limited environments Slow Gravity limited Small Animals Heat loss size2 Heat generation size3 Large energy intake (food)

  5. Why can’t I walk on water? weight scales as l3 surface tension scales as l As animals become smaller, weight decreases more rapidly than surface tension.

  6. Why can’t I lift a car? weight scales as l3 strength scales as l2 ants can carry 50 time their weight a human shrunk to ant size could carry 300 times his/her own weight an ant increased to human size will not be able to support it’s own weight

  7. The Industrial Revolution

  8. Example: Digital Mirrors Digital Light Processing (DPL)

  9. http://www.dlp.com/

  10. Digital Light Processing: A New MEMS-Based Technology By Larry Hornbeck

  11. Systron Donner Inertial Division

  12. Systron Donner Inertial Division

  13. Acceleration direction Support Arms Mass Anchor Anchor Displacement sensor Accelerometer: Analog Devices Inc. Commercially available two-axis accelerometer

  14. A Polysilicon Accelerometer (2 Microns Thick) Mass Sensing Electrodes Support Arms Support arms are 2 microns square and ~ 100 microns long From John Yasaitis, Analog Devices Inc

  15. Closeup of ADI Accelerometer From John Yasaitis, Analog Devices Inc

  16. Accelerometer

  17. From John Yasaitis, Analog Devices Inc

  18. Why silicon?

  19. Many Properties Depend on Atomic Structure Silicon Crystalline Materials Regular arrangement of atoms with long range order

  20. holes electrons Si Si Si 0.235 nm 0.543 nm Si Si Si Si Si Si Silicon Si semiconductor 5 silicon atoms in a unit cell Diamond lattice Covalent bonds 14 electrons 4 valence electrons Silicon molecules: http://www.eere.energy.gov/pv/simolecule.html

  21. Integrated Circuits in 1958 Jack Kilbyat Texas Instruments

  22. Integrated Circuits in 1962 RTL Logic (Noyce and Hoerni)

  23. Integrated Circuits in 1965 Operational Amplifier, Fairchild ua 709

  24. Integrated Circuits in 1991 Power PC, AIM (Apple-IBM-Motorola Alliance)

  25. Today’s Microelectronics & MEMS Analog Devices, Accelerometers and Gyroscopes

  26. Decrease in Minimum Feature Size with Time (Moore’s law)

  27. Clean Room Classification English system: Numerical designation of the class is maximum allowable number of particles that are 0.5 mm and larger per cubic foot of air. Metric system: Numerical designation of the class is taken from the Logarithm (base 10) of the maximum allowable number of particles that are 0.5 mm and larger per cubic foot of air IC is very sensitive to particles. It usually requires Class 10 or better MEMS is more robust to particulates

  28. Microfabrication Silicon Oxidation Photoresist Deposition Masking and Exposure Figures from May and Sze

  29. Photoresist Development Doping Si02 etching Metallization Metallization Patterning Photoresist Cleaning Figures from May and Sze

  30. Thermal Oxidization • Dry Oxidization : Si (solid) + O2 (gas)  SiO2 (solid) • Wet Oxidization: Si (solid) + 2H2O (gas)  SiO2 (solid) + 2H2 (gas)

  31. Photolithography: Pattern Transfer The remaining image after pattern transfer can be used as a mask for subsequent process such as etching, ion implantation, and deposition.

  32. bound electrons Si Si Si Si Si Si Si B Si Si P Si Si Si Si Si Si Si Doped Silicon P- doped N- doped free electrons holes Silicon molecules: http://www.eere.energy.gov/pv/simolecule.html

  33. Diffusion Constant source – High surface concentrations, shallow, "deposition“ Limited source – Low surface concentrations, deep, "drive-in"

  34. Ion-implantation

  35. Thin Film Deposition Thermal Evaporator • Pump down to 1 mtorr • ( 1 torr = 1 mmHg) • Place wafers upside down to reduce particles • Heat sources until white hot • Low pressure = long mean-free-path (i.e., directional deposition) • Use shutter for better timing

  36. LIGA: electroplating nickel www.me.mtu.edu/~microweb

  37. http://mems.sandia.gov/gallery/images.html

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