introduction to microelectromechanical systems (mems… · 2015. 11. 23. · mems 487 session #1...
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MEMS 487Session #1Spring 03
INTRODUCTION TO
MICROELECTROMECHANICAL SYSTEMS
(MEMS)
520/530.487
Instructors:Andreou HemkerSharpe
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
What is (are) MEMS (MEMSs)?
(Microsystems)
MICROELECTROMECHANICAL SYSTEMS
(MEMS)
Small structures, sensors, actuators, machines, and robots
Maximum dimensions on the order of millimeters
Minimum features on the order of micrometers
Issues in Mechanical Testing
• Specimen preparation andhandling
• Friction in mechanism
• Direct strain measurement
Test section is 5 micronswide and 500 microns long.Hair is ~ 80 microns in diameter.
MICROELECTROMECHANICAL SYSTEMS
(MEMS)
• May not be electromechanical; may be electrochemical or purely mechanical
• Originated approximately 16 years ago
• Originally work of electrical engineers
How to make MEMS
Surface micromachining - deposit sacrificial layer, then desiredmaterial, 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
Specimens
Narrow Thin-Film - 14 on 1 cm x 1cm die.Top end fixed; bottom gripped electrostatically. Test section is3.5 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.
AN EXAMPLE
Digital Mirrors
Senturia Ch 20
And
Digital Light Processing: A New MEMS-Based TechnologyBy Larry Hornbeck
See also
Tutorial: Micromachining in OpticsBy Gregory Magel
Both from www.dlp.com (a part of www.ti.com)
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
eye
16 ms
Color mix can be
AnalogReflected as from paintTransmitted as thru transparencyOrDigitalEmitted for different times
3 color -- 5.3 ms for each
256 bits -- 5.3/256 = 0.021 ms for each bit
Switching frequency per bit = 48 kHz
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
Hornbeck Fig 2
Hornbeck Fig 15
Hornbeck Fig 5
Hornbeck Fig 4
Hornbeck Fig 6
Hornbeck Fig 7
Hornbeck Fig 20
Hornbeck Fig 19
Each mirror is 16 microns square
Senturia Fig 20.1
Hornbeck Fig 18
Hornbeck Fig 14
Hornbeck Fig 11
Hornbeck Fig 17
Hornbeck Fig 27
Disciplines or topics involved
Electrical engineering – Andreou
Materials science – Hemker
Mechanics – Sharpe
Others such as optics, etc.
Malur Fig 5.2
MEMS is not just planar
The MEMS Industry
History from T. Tsuchiya
0.5
1
1 .5
2
2 .5
3
3 .5
4
1992 1994 1996 1998 2000 2002 2004 2006
Total M EM S M arket
Do
lla
rs -
Bil
lio
ns
From Maluf, Table 1.2
0
40
80
120
160
200
1830 1840 1850 1860 1870 1880 1890 1900
Ra
il M
ile
s -
10
00
Y ear
Telegraph 1844
BessemerSteel1856
Railroad Mileage in U.S.
Historical Statistics of the U.S.
Johns HopkinsUniversity1876
Camden Station - Baltimore
1856 2000
MEMS Industry Group
MEMS Industry Group
MEMS Industry Group
MEMS Industry Group
MEMS Industry Group
The State of MEMS Education
Progression of MEMS
(from Bill Trimmer)
• “Isn’t it neat?”
• Potential uses
• A few applications
• Widespread commercialization
~ 1985
2000
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
http://web.mit.edu/microsystem-design/www/
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
The Course
The prerequisite is Senior or Graduate standing or permission.
Instructors:
Professor Andreas G. Andreou, Stieff Bldg. 120, 410-516-8361, [email protected] Kevin J. Hemker, Latrobe Hall, 410-516-4489, [email protected] William N. Sharpe Jr., Latrobe Hall 126 , 410-516-7101, [email protected]
Website: http://www.ece.jhu.edu/faculty/andreou/487
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 notbe accepted without advance arrangements.
Date Topics Instructor Text Homework Lab
30 Jan
31
Introduction
Introduction
BS
AACh 1
6 Feb
7
Materials KHCh 8
Accelero-meters
13
14
ProcessingOxidn, lithog,
KH + AACh 3
By BS
20
21
ProcessingFilm depn, LIGA
KH + AACh 4
By BS
27
28
Mechanics BS Ch 9, 10
6 Mar
7
MIDTERM
Pressure gage
AA
AA
Ch 18
10-14 SPRING BREAK
Some topics will be familiar; Lab exercises are to be arranged
20
21
Fluids BS + colleagues
Ch 13
27
28
Electromagnetics+Electronics
AA Ch 6, 11, 14, 16
By AA
3 Apr
4
Electromagnetics+Electronics
AA By AA
10
11
Modelling and Simulation AA
Ch 5
17
18
DNA case study KH Ch 22
By BS
24
25
Accelerometer case study
BSCh 19
By BS
1 May
2
TBA
8-15 FINAL EXAM
An Accelerometer
Systron Donner Inertial Division
Systron Donner Inertial Division
Analog Devices IncAccelerometer
Commercially available two-axis accelerometer
Mass
Accelerationdirection
AnchorAnchor
Displacement sensor
SupportArms
Microaccelerometers
A Polysilicon Accelerometer(2 Microns Thick)
Mass
SupportArms
SensingElectrodes
Support arms are 2 microns square and ~ 100 microns long
From John Yasaitis, Analog Devices Inc
Overview of ADXL Accelerometer
Closeup of ADI Accelerometer
XL78 Beam DesignInstead of the mass being a central element with Fingers coming out the sides, the mass is a box withFingers coming into the interior of the box
MOVABLEFRAME
AC
CE
LER
AT
ION
UNIT FORCINGCELL
UNIT SENSINGCELL
MOVINGPLATE
FIXEDPLATES
PLATECAPACITORS
ANCHOR
ANCHOR
VIN -
VIN +
VOUT
Amp
VIN -
VIN +
VOUT-
+
+
-
AmpFIXEDPLATES
PLATECAPACITORS
ANCHOR
MOVABLEBEAMEarlier
Designs
XL78
ADXL78 accelerometer
XL78 Beams MagnifiedSpringMass (box shaped)
Finger attached to mass
Second Mass
What I do
Specimens
Narrow Thin-Film - 14 on 1 cm x 1cm die.Top end fixed; bottom gripped electrostatically. Test section is3.5 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.
Preparation and Handling of Wide Polysilicon Specimen
Deposit specimen on die; then etch away part of die
GripEnd
SupportStrip
TensileSpecimen
AS RECEIVED AFTER ETCHING
Wide Specimen
Glued in grips with support strips cut
0.00
0.25
0.50
0.75
1.00
1.25
-0.2 0.0 0.2 0.4 0.6 0.8
Stress vs Biaxial Strain for Polysilicon
AutoCAD Drawing of Microcissors
SEM photos of Microscissors
Microscissors after etching away substrate
Homework
• Look at a journal article
• Look at a website
• Look at an accelerometer
due Thus, Feb 6