INTRODUCTION TO MICROELECTROMECHANICAL SYSTEMS (MEMS) 520/

Transcription

1 INTRODUCTION TO MICROELECTROMECHANICAL SYSTEMS (MEMS) 520/ Instructors: Andreou Hemker Sharpe Today: What are MEMS - TI digital mirror example The MEMS industry - history and size The state of MEMS education The course - schedule, rules, etc. Accelerometer visual examination What I do - materials testing MEMS 487 Session #1 Spring 03

2 What is (are) MEMS (MEMSs)? (Microsystems)

3 MICROELECTROMECHANICAL SYSTEMS (MEMS) Small structures, sensors, actuators, machines, and robots Maximum dimensions on the order of millimeters Minimum features on the order of micrometers

4 Issues in Mechanical Testing Specimen preparation and handling Friction in mechanism Direct strain measurement Test section is 5 microns wide and 500 microns long. Hair is ~ 80 microns in diameter.

5 MICROELECTROMECHANICAL SYSTEMS (MEMS) May not be electromechanical; may be electrochemical or purely mechanical Originated approximately 16 years ago Originally work of electrical engineers

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7 How to make MEMS Surface micromachining - deposit sacrificial layer, then desired material, pattern and etch each, dissolve away sacrificial layer Bulk micromachining - pattern and etch silicon crystal into desired configuration LIGA related - deposit thicker layers (electroplate) into pre-cut mold

8 Specimens Narrow Thin-Film - 14 on 1 cm x 1cm die. Top end fixed; bottom gripped electrostatically. Test section is 3.5 µm x 50 µm x 1000 µm. Wide Thin-Film - One on 1 cm x 1 cm die. Center section released and ends glued into test machine. Test section is 3.5 µm x 600 µm x 4 mm. Thick-Film - Six on 1 cm X 1 cm die. Each released and placed in test machine. Test section is 200 µm x 200 µm x 2 mm.

9 AN EXAMPLE Digital Mirrors Senturia Ch 20 And Digital Light Processing: A New MEMS-Based Technology By Larry Hornbeck See also Tutorial: Micromachining in Optics By Gregory Magel Both from (a part of

10 The eye is an integrator NTSC video is 60 Hz 60 Hz is 16 ms period The amount of time it is exposed to a color mix of RGB determines the color it sees Color mix can be Analog Reflected as from paint Transmitted as thru transparency Or Digital Emitted for different times 3 color ms for each eye 256 bits /256 = ms for each bit Switching frequency per bit = 48 khz 16 ms

11 Projection can be Different color phosphors as in CRT or TV Transmission as in film or in LCD (as in Epson) Reflection as in DMD Digital Micromirror Device GLV - Grating Light Valve

12 Hornbeck Fig 2

13 Hornbeck Fig 15

14 Hornbeck Fig 5

15 Hornbeck Fig 4

16 Hornbeck Fig 6

17 Hornbeck Fig 7

18 Hornbeck Fig 20

19 Hornbeck Fig 19 Each mirror is 16 microns square

20 Senturia Fig 20.1

21 Hornbeck Fig 18

22 Hornbeck Fig 14

23 Hornbeck Fig 11

24 Hornbeck Fig 17

25 Hornbeck Fig 27

26 Disciplines or topics involved Electrical engineering Andreou Materials science Hemker Mechanics Sharpe Others such as optics, etc.

27 Malur Fig 5.2 MEMS is not just planar

28 The MEMS Industry

29 History from T. Tsuchiya

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31 Total MEMS Market Dollars - Billions From Maluf, Table 1.2

32 Railroad Mileage in U.S. 200 Rail Miles Telegraph 1844 Bessemer Steel 1856 Johns Hopkins University Year Historical Statistics of the U.S.

33 Camden Station - Baltimore

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36 MEMS Industry Group

37 MEMS Industry Group

38 MEMS Industry Group

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40 MEMS Industry Group

41 MEMS Industry Group

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43 The State of MEMS Education

44 Progression of MEMS (from Bill Trimmer) Isn t it neat? ~ 1985 Potential uses A few applications Widespread commercialization 2000

45 Texts and References Text - Microsystem Design by Steve Senturia. or MEMS and Microsystems by Hsu References Fundamentals of Microfabrication by Madou Micromachined Transducers Sourcebook by Kovacs Micromechanics and MEMS by Trimmer An Introduction to MEMS by Maluf The MEMS Handbook by Gad-el-Hak

46 Web site for the text Major conferences Each January - IEEE MEMS XX - US, Japan, Europe June of odd years - Transducers XX - US, Japan, Europe June of even years - Hilton Head XX - US and limited Each November - Multiple sessions at ASME meeting

47 The Course

48 The prerequisite is Senior or Graduate standing or permission. Instructors: Professor Andreas G. Andreou, Stieff Bldg. 120, , Professor Kevin J. Hemker, Latrobe Hall, , Professor William N. Sharpe Jr., Latrobe Hall 126, , Website: The class meets ThF 1:30-3:00 in Hodson 210 Lab sequences are three weeks long; students must sign up for one lab session in each three-week period. Lab times and locations to be determined. The text is Microsystem Design by S. Senturia from Kluwer Academic Publishers. The tentative grading policy is: Homework 20% Lab Exercises 20% Midterm Exam 30% Final Exam 30% Homework is due at the beginning of the class period on the date due. Late homework will not be accepted without advance arrangements.

49 Date Topics Instructor Text Homework Lab 30 Jan 31 Introduction Introduction BS AA Ch 1 6 Feb 7 Materials KH Ch 8 Accelerometers Processing Oxidn, lithog, KH + AA Ch 3 By BS Processing Film depn, LIGA KH + AA Ch 4 By BS 27 Mechanics BS Ch 9, Mar 7 MIDTERM Pressure gage AA AA Ch SPRING BREAK Some topics will be familiar; Lab exercises are to be arranged

50 Apr May Fluids BS + colleague s Electromagnetics + Electronics Electromagnetics + Electronics Modelling and Simulation DNA case study Accelerometer case study TBA Ch 13 AA Ch 6, 11, 14, 16 AA AA KH BS Ch 5 Ch 22 Ch 19 By AA By AA By BS By BS FINAL EXAM

51 An Accelerometer

52 Systron Donner Inertial Division

53 Systron Donner Inertial Division

54 Microaccelerometers Analog Devices Inc Accelerometer Acceleration direction Support Arms Anchor Mass Anchor Displacement sensor Commercially available two-axis accelerometer

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

56 Overview of ADXL Accelerometer

57 Closeup of ADI Accelerometer

58 XL78 Beam Design Instead of the mass being a central element with Fingers coming out the sides, the mass is a box with Fingers coming into the interior of the box V IN + Earlier Designs PLATE CAPACITORS + - MOVABLE BEAM + Amp V OUT FIXED PLATES - V IN - ANCHOR ANCHOR XL78 PLATE CAPACITORS MOVABLE FRAME V IN + ACCELERATION UNIT SENSING CELL MOVING PLATE FIXED PLATES UNIT FORCING CELL Amp V OUT V IN - ANCHOR

59 ADXL78 accelerometer

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61 XL78 Beams Magnified Mass (box shaped) Spring Second Mass Finger attached to mass

62 What I do

63 Specimens Narrow Thin-Film - 14 on 1 cm x 1cm die. Top end fixed; bottom gripped electrostatically. Test section is 3.5 µm x 50 µm x 1000 µm. Wide Thin-Film - One on 1 cm x 1 cm die. Center section released and ends glued into test machine. Test section is 3.5 µm x 600 µm x 4 mm. Thick-Film - Six on 1 cm X 1 cm die. Each released and placed in test machine. Test section is 200 µm x 200 µm x 2 mm.

64 Preparation and Handling of Wide Polysilicon Specimen Deposit specimen on die; then etch away part of die Support Strip AS RECEIVED Tensile Specimen AFTER ETCHING Grip End

65 Wide Specimen Glued in grips with support strips cut

66 Stress vs Biaxial Strain for Polysilicon

67 AutoCAD Drawing of Microcissors

68 SEM photos of Microscissors

69 Microscissors after etching away substrate

70 Homework Look at a journal article Look at a website Look at an accelerometer due Thus, Feb 6

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