1. Why do we put the micro in microelectronics?

2. Why Micro? 1.Lower Energy and Resources for Fabrication 2.Large Arrays 3.Minimally Invasive 4.Disposable 5.Smaller Time Scales 6.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 size 2 Heat generation size 3 Large energy intake (food)

5. Why can’t I walk on water? weight scales as l 3 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 l 3 strength scales as l 2 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

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

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

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

18. Accelerometer

19. From John Yasaitis, Analog Devices Inc

20. Why silicon?

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

22. 22 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 0.543 nm0.235 nm Si electronsholes

23. Integrated Circuits in 1958 Jack Kilby at Texas Instruments

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

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

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

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

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

29. Clean Room Classification English system: Numerical designation of the class is maximum allowable number of particles that are 0.5  m 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  m 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

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

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

32. Dry Oxidization : Si (solid) + O 2 (gas)  SiO 2 (solid) Wet Oxidization: Si (solid) + 2H 2 O (gas)  SiO 2 (solid) + 2H 2 (gas) Thermal Oxidization

33. 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.

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

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

36. Ion-implantation

37. Thermal Evaporator Pump down to 1  torr ( 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 Thin Film Deposition

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

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