¿ Quien soy y por qué estoy aquí ?

1. ¿Quien soy y porquéestoyaquí? Thomas Adams, PhD En el mundo hispano: Tomás McDaniel Adams McDaniel Soy profesor de ingeniería mecánica en Rose-HulmanInstitute of Technology Mis estudiantes me llaman “Doctor Tom”. Más cabello Más cabello

2. Terre Haute, Indiana, USA Privateuniversitywith~ 2000 students, mostly undergraduate (pregrado) Ciencias, ingeniería, y matemáticas

3. Introduction to MEMS(micro-tecnología)

4. Movie of a motor Motor and gear train movies from Sandia National Laboratory

5. Movie of a motor Motor and gear train movies from Sandia National Laboratory

6. Still pictures of motor Another view of the engine A still picture of the motor… with a spider mite on it!

7. Movie of a motor Motor and gear train movies from Sandia National Laboratory

8. Movie of a motor Motor and gear train movies from Sandia National Laboratory

9. Movie of a motor Motor and gear train movies from Sandia National Laboratory

10. Course overview and objectives Overview: This course gives an introductory treatment of MEMS, also known as microsystems and micro-technology (MST). Fabrication, device functionality, and modeling strategies are explored. • Objectives (Objetivos): • Through the student work in the course program, the student will be able to: • Identify the relative importance of different physical phenomena based on length scale • Identify and describe the most commonly used fabrication processes in making MEMS devices • For a simple MEMS device, identify the major required fabrication steps and put them in the appropriate order (create a process flow) • Use the principles of elastic theory in predicting the stress/strain state of MEMS devices

11. Course overview and objectives • Objectives (Objetivos) continued: • Through the student work in the course program, the student will be able to: • List a number of common MEMS transducers and explain their operating principles • Explain in detail the operating principles of a piezoresistive MEMS pressure sensor, and predict the performance of such a device • Give a well-formed argument considering a microtechnology-based solution for a given problem • Gain experience using English in spoken and written forms as a means of expressing technical ideas

12. Topics Specific topics 1. Introduction to MEMS: Scaling and basic fabrication 2. The Substrate 3. Additive Techniques 4. Creating Patterns – Lithography 5. Bulk Micromachining 6. Surface Micromachining 7. Process flow 8. Solid mechanics 9. Overview of MEMS operating principles 10. Modeling case study: piezoresistive sensors

13. References • Required • Introductory MEMS: Fabrication and Applications by Thomas Adams and Richard Layton, Springer • Disponible (¡gratis! ) en los bases de datos de PUCP: • http://biblioteca.pucp.edu.pe/colbasd.html • Suggested (sugerencias) • Fundamentals of Microfabrication by Marc J. Madou, CRC Press. • Microsystem Design by Stephen Senturia, Springer • Foundations of MEMS by Chang Liu, Prentice Hall.

14. ¿Cómova a ser el curso? I will correct your English, but it will not affect your grade. The reading summaries will be based on effort. En y fuera de clase Puntos fáciles Notas: Problems/reading summaries 10% Midterm exam 30% Final Exam 35% Report15% Attendance/participation 10% 100% Puntos fáciles • No quieroqueestecurso sea unadictaciónsino un diálogo. Poresocreoqueesimportantequenoscharlemos en unamanerarelajada para entendermejor y practicarnuestrosidiomas. (Ustedes, inglés y yo, español.)

15. ¿Cómova a ser el curso? • Reading summaries: • One each week on assigned reading • Inlcude a briefsummary of themajorpoints (¡No me den otro libro!) • Describe thethingyoufeelyouunderstandthebest (Algo que entiendes bien) • Describe thethingyoufeelyouunderstandtheleast (Algo que no entiendes para nada) Report: Can be about any aspect of MEMS you would like—a new or advanced fabrication technique not covered in the book/lectures, a particular MEMS device, a particular class of MEMS technology, modeling strategies, etc. • Some examples: • Focused ion beam instruments • Micro fuel celltechnology • Dyanamicsystemsmodeling in MEMS • Advancedphotolithographytechniques • Digital microfluidics • MEMS gyroscopes • MEMS packaging

16. What are MEMS? Acronym (acrónimo) for micro-electro-mechanical systems. Micro: Small size. The basic unit of measure is the micrometer or micron (μm) 1 μm = 10-6 m Electro: MEMS have electrical components (quizás) Mechanical: MEMS have moving parts (quizás) • Systems: Refers to integration of components. (Funcionanjuntos.)

17. Examples of MEMS You can find MEMS in • Automobiles (Air bag sensors) • Computer printers (Ink jet print heads) • Cell phones (RF devices) • Lab-on-a-chip (Microfluidics) • Optical devices (Micromirrors) • Lots of other things

18. MEMS accelerometer MEMS accelerometers are used widely to deploy airbags. (Casitodos los coches los tienen.)

19. MEMS accelerometer Most accelerometers use electrical capacitance to sense acceleration. Se llama “comb structure (estructura de peine) • Adapted from Microsystem Design by Stephen Senturia, Springer

20. Movie of a motor Can be used in reverse as an actuator. With alienating current (corrientealterna) it becomes a motor. In MEMS this type of motor is called a comb drive. Comb drive

21. Ink jet print heads Ink dots are tiny (10-30 per mm) and so are the nozzles that fire them.

22. Ink jet print heads • Ink-filled chambers are heated by tiny resistive heating element • By heating the liquid ink a bubble is generated

23. Ink jet print heads • The vaporized part of the ink is propelled towards the paper in a tiny droplet • Chambers are filled again by the ink through microscopic channels

24. Micromirrors Micromirrorsare used as optical switches and even computer displays

25. Micromirrors An array of micromirrors

26. Micromirrors Video of micromirror actuation from Sandia National Labs

27. More examples Labs-on-a-chip can replace entire chemical and biological analysis laboratories.

28. More examples There are many other MEMS devices in development…

29. More examples …some more useful than others.

30. Why go micro? What are some reasons that you would want to make micro-sized devices? • Smaller devices require less material to make. (Earth has limited resources.) • Smaller devices require less energy to run. • Redundancy can lead to increased safety. (You can use an array of sensors instead of just one.) • Micro devices are inexpensive (?) • Less material • Can be fabricated in batch processes Más cabello

31. Why go micro? What are some reasons that you would want to make micro-sized devices? • Micro devices are minimally invasive and can be treated as disposable. (Especially good for chemical and medical applications.) • Many physical phenomena are favored at small scales.

32. Examples of small scale effects Hot arm actuator A poly-silicon hot-arm actuator fabricated using surface micromachining

33. Examples of small scale effects Hot arm actuator + V - I A poly-silicon hot-arm actuator fabricated using surface micromachining

34. entry port separation column junction Examples of small scale effects Electro-osmotic flow + V- Electricity can move fluids!

35. Scalinglaws Activity – Demo with key and key ring Water spills out of key ring, but it stays in the smaller holes of the key (llave). Why? • Gravity (weight) pulls water down. Surface tensionholds water up. Which one wins? (¿Quiengana?) • Weight depends on volume/area/length • Surface tension depends on volume/area/length • Entonces,

36. Scalinglaws Tetoca a ti – La musaraña (shrew) es el animal máspequeñoquees de sangrecaliente. Si no come constantemente, se muere. Usa “scale analysis” para explicar.

37. Scalinglaws Tetoca a ti – Use scale analysis to show that every animal on the planet can jump approximately the same height. Esdecir, que la habilidad de saltar no cambia con la dimensión.

38. Scalinglaws Favorable scalings at the microscale • Heat transfer (tranferencia del calor) is faster • Frequency response is faster • Electrostatic forces are more prominent (más fuertes) • Surface tension can move fluids • And more

39. How are MEMS made? • Many techniques borrowed from integrated circuit (IC) fabrication • Silicon wafers are commonly used • Bulk micromachining • Surface micromachining • Other techniques

40. How are MEMS made? Bulk micromachining example - A diaphragm for a pressure sensor Membrane is piezoresistive; i.e., the electrical resistance changes with deformation. Adapted from MEMS: A Practical Guide to Design, Analysis, and Applications, Ed. Jan G. Korvink and Oliver Paul, Springer, 2006

41. Bulk micromachining Bulk micromachining example - A diaphragm for a pressure sensor Mask Grow SiO2 SiO2 chemically etched with HFl Unexposed resist removed Opaque region Silicon anisotropicallyetched with KOH Silicon wafer Glass plate Spin on photoresist Unexposed photoresist removed by developer

42. Bulk micromachining Depending on the chemical/structure combinations, etching can be… or anisotropic • isotropic Anisotropic etches • 001 silicon wafer • 011 silicon wafer

43. Surface micromachining SomeJengapieces are removed. The onesthatremainformthe MEMS structure. The Si waferfunctionslikethebiggreen flat plate. + = Surface micromachining

44. Surface micromachining Surface micromachining example – Creating a cantilever Deposit aluminum (structural layer—the Jenga pieces that remain) Deposit polyimide (sacrificial layer—the Jenga pieces that are removed) Remove sacrificial layer (release) Etchpart of thelayer. Silicon wafer (Green Lego® plate)

45. Micromachining Complicated structures can be made by combining these techniques and repeating

46. Micromachining Everything has to be veryclean! (¡Ojala estén limpias todas cosas!)

47. Surface micromachining Tetoca a ti—Come up with the process steps needed to make the cantilever in the last example. (Deposition, photolithography, etc.) Sideview Top view Hint: Youwillneedtwomasks and twophotolithographysteps.