Transcript Highly Adaptable MEMS-Based Display with Wide Projection Angle

Highly Adaptable MEMS-Based Display
with Wide Projection Angle
Veljko Milanović, Kenneth Castelino, Daniel T. McCormick
Adriatic Research Institute
828 San Pablo Ave., Ste. 109, Berkeley, CA 94706
MEMS 07’ p 143~146
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Outline
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MEMS-BASED DISPLAY
Two Basic MEMS-based projection display :
Reflective displays,pioneered by Texas Instrument
Diffractive display,pioneered by Silicon Light Machines
large deflection angles
large displacement
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Research Chart Analysis
Year
2000
2001
2002
2003
2004
2005
2006
2007
DRIE Devices
tunable field emission devices (FEDs).
Torsional Micromirrors Lateral Actuators
Sunghoon , Two-Axis
[4]Single axis rotation
[15] Two-Axis Scanners
[7] 2 DoF linkages to a central stage.
[14] 3 DoF With Large Static Rotation and Piston Actuation
Fully-Functional (high-speed /low-power)
Large rotation with contact to neighboring elements
Display with Wide angle
[18] Improve image quality/re-flesh rate/brightness
High Temperature Operation
Production Engineering
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A Brief History (1)
Year Publish
Veljko Milanovic´, Member, IEEE
Contribution
 [1] 2000 (Journal ) DRIE Devices were fabricated on silicon-on-insulator (SOI) wafers
 [2] 2000 (Journal ) Integration of optimized microelectromechanical systems (MEMS) in RF systems on
substrates such as sapphire, GaAs, and even CMOS.
 [8] 2001 (Conf.)
Integration of a wide variety of SOI-MEMS sensors, actuators and micromirrors. 1-axis mirror
 [9 ] 2001 (Conf.)
The micromirror structures are laterally electrostatically actuated, torsionally suspended
micromirrors with static scanning deflection of over 40° peak-to-peak optical angle.
 [10] 2001 (Conf.)
Enabling additional independent degrees of freedom of operation: both upward and downward
vertical pistoning motion as well as bi-directional rotation.
 [3] 2001 (Journal ) Utilize MEMS actuators to laterally adjust electrode distances.
 [11] 2002 (Conf.)
Add vertical combdrives. + new beam structure which decreases lateral movement while
enabling rotation.
 [12] 2002 (Conf.)
Providing 1DoF and 2DoF rotation of micromirrors ; static optical deflection from –20° to +19°
 [4] 2003 (Journal ) Laterally electrostatically actuated, torsionally suspended (SOI) micromirrors with a static
optical deflection angle of over 40 peak-to-peak.
 [13] 2003 (conf.)
Allow larger static rotations of the micromirror from the combdrive-stroke limited rotation
The static optical deflection of the x-axis up to 9.6° and of the y-axis up to 7.2°, are achieved
for <275 Vdc ; lower-voltage operation exhibits static optical deflection about the x-axis to
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10.8° and about the y-axis to 11.7°, for <85 Vdc.
A Brief History (2)
Year Publish
Veljko Milanovic´, Member, IEEE
Contribution
 [5] 2004 (Journal ) vertical comb drives micromachined from the back side and front side of a 50- μm siliconon- insulator device layer.
 [6] 2004 (Journal ) larger static rotations of the micromirror from the comb-drive
 [7] 2004 (Journal ) high aspect ratio silicon-on-insulator microelectromechanical systems (SOI-MEMS) by
enabling additional independent degrees of freedom of operation: both upward and
downward vertical pistoning motion as well as bi-directional rotation
[14] 2004 (conf.) Each actuator can rotate bi-directionally to raise or lower its linkage,giving the stage the required
(3 DoF. )
 [15] 2004 (conf.) Tip-Tilt-Piston Actuators for High Fill-Factor Micromirror Arrays, (3 DoF)
 [19] 2004 (joural) Tip-tilt-piston actuators for high fill-factor micromiror arrays
 [16] 2006 (conf.) 95% - chosen such that the mirrors would have sufficient space for large rotations without making
contact to neighboring elements.
 [17] 2007 (conf.) display system with a very wide projection angle of up to 120°.
 [18] 2007 (conf.) To improve image quality, reflesh rate, brightness . Horizonal axis resonant frequencies ranging
from 10 kHz to 21.5 kHz for mirror sizes ranging from 1.2mm to 0.8 mm
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Basic Manufacture Process
Deep reactive ion etch (DRIE) [1]
The biggest obstacle in SOI-MEMS mirrors is the
four-mask process layers with DRIE:
inherent lack of out-of-plane motion.,[2001]
two for front-side and two for back-side
etching.
 High layers(50 μm)
Three -level
Lower layers(30 μm)
Vertical Comb
Upper layers (30 μm)
Backside opening
 releases large areas for out-of plane
motion and rotation of micro mirrors.
 up and down-actuating comb drives
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Single axis rotation
Laterally actuated ,2001
Problem:
radius of curvature,
dynamic deflection,
Bucking
50V  100 angle
providing 1DoF (or single-axis) rotation
out-of-wafer-plane degrees of freedom
(DoF).
high aspect ratio
Vertical actuated ,2003
up-actuating comb drives
down-actuating comb drives
Rotor & Stator
2 x 2=4 Types
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Problem:
radius of curvature
bending
Two axis rotation-Vertical,island
x rotating
Y rotating
vertical comb drives
 Isolation island
 upper-comb and Lower-Comb
 x rotating + Y rotating
Type 1- vertical combdrives ,2002
A High Aspect Ratio 2D Gimbaled Microscanner with Large Static Rotation,2002
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Two axis rotation-Vertical,rotation transformer
2 generation
Comb drive
 single-axis+ single-axis
 unidirectional rotation
Rotation transformer Mechanism
Type 2- vertical combdrives ,2004
low voltage
large displacement
Veljko Milanović, Int. Conf. on Microelectromechanical Systems, MEMS2004
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3 generation( Three axis rotation)
3 DoF tip-tilt-piston actuators
Stator
Rotor
Linkage + Rotation transformer
[19 ]D. T. McCormick, 2004 Solid State Sensor,Actuator and Microsystems Workshop
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Micromirrors fully assembled
1.2mm
Backside silicon micromirrors
fully assembled
[16] D. T. McCormick ,2006 IEEE/LEOS Optical MEMS
four vertical combdrive rotators
four elements being driven by the software
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Summary
A. Specification Achieved :
 3-level selective DRIE process SOI Wafer
 low-inertia mirror-apertures 1 mm x 1 mm
 rotations of the micromirror from 20° of peak-to-peak optical deflection
 maximum displacement of -12 μm to 12 μm
 125 μm stand-off pedestal
 15 μm thickness( metalized with a 100 nm thick layer of Al)
B. The important Milestone & Contribution history
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C. Key
fabrication process presented in this work
 All combfingers are fabricated isolated and independently
 Vertical combdrive sets
DRIE
large displacement
 Comb-fingers is controlled several μm of overlap
 Masks for etching of comb-fingers are self-aligned by a single mask
 The process requires selective, high aspect ratio multilevel etching,
Etch time is very important
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Referance(1)
[1] V. Milanović, L. Doherty, D. Teasdale, C. Zhang, V. Nguyen, M. Last, and K.Pister, "Deep Reactive Ion
Etching for Lateral Field Emission Devices," IEEE Electron Device Letters, vol. 21, no. 5, May. 2000.
[2] V. Milanović, M. Maharbiz, and K. Pister, "Batch Transfer Integration of RF Microrelays," IEEE Microwave
and Guided Wave Letters, vol. 10, no. 8, pp. 313-315, Aug. 2000.
[3] V. Milanović, L. Doherty, D. Teasdale, S. Parsa, C. Zhang, and K. Pister, "Micromachining Technology for
Lateral Field Emission Devices," IEEE Tran. On Electron Devices - special issue on vacuum electronics, vol.
48, no. 1, pp.166-173, Jan. 2001.
[4] V. Milanović, M. Last, K.S.J. Pister, "Laterally Actuated Torsional Micromirrors for Large Static
Deflection," IEEE Photonics Technology Letters, vol. 15, no. 2, pp. 245-247, Feb. 2003.
[5] V. Milanović, S. Kwon, L. P. Lee, "High Aspect Ratio Silicon Micromirrors with Large Static Rotation and
Piston Actuation," IEEE Photonics Technology Letters, vol. 16(8) , Aug. 2004, pp. 1891 - 1893.
[6 ]V. Milanović, D. T. McCormick, G. Matus, "Gimbal-less Monolithic Silicon Actuators For Tip-Tilt-Piston
Micromirror Applications," IEEE J. of Select Topics in Quantum Electronics,Volume: 10 , Issue: 3 , May-June
2004, Pages:462 – 471
[7 ]V. Milanović, "Multilevel-Beam SOI-MEMS Fabrication and Applications,“ IEEE/ASME Journal of
Microelectromechanical Systems, vol. 13, no. 1, pp. 19-30, Feb. 2004.
[8 ]V. Milanović, M. Last, K.S.J. Pister, "Torsional Micromirrors with Lateral Actuators,” Trasducers'01 Eurosensors XV conference, Muenchen, Germany, Jun. 2001.
[9 ]V. Milanović, M. Last, K.S.J. Pister, "Monolithic Silicon Micromirrors with Large Scanning Angle,”
Optical MEMS 2001, Okinawa, Japan, Sep. 2001.
[10] V. Milanović, “Multilevel-Beam SOI-MEMS for Optical Applications,” Proc. 9th IEEE Int. Conf. on
Electronics, Circuits and Systems - ICECS'02, Dubrovnik, Croatia, Sep. 2002. pp. 281-215
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Referance(2)
[11] V. Milanović, L. Doherty, “A Simple Process for Lateral Single Crystal Silicon Nanowires,” to be
presented, Int. Mechanical Eng. Conf. And Exhibit IMECE'02, New Orleans, LA, Nov. 2002.
[12]V. Milanović, S. Kwon, L. P. Lee, “Monolithic Vertical Combdrive Actuators for Adaptive Optics,”
IEEE/LEOS Optical MEMS 2002, Lugano, Switzerland, Aug. 2002.
[13] V. Milanović, G. Matus, T. Cheng, B. Cagdaser, “Monolithic High Aspect Ratio Two-axis Optical Scanner
in SOI,” Int. Conf. on Microelectromechanical Systems, MEMS2003, Kyoto, Japan, pp. 255-258, Jan. 2003.
[14] V. Milanović, G. Matus, D. T. McCormick, “Tip-Tilt-Piston Actuators for High Fill-Factor Micromirror
Arrays," at the Hilton Head 2004 Solid State Sensor, Actuator and Microsystems Workshop, Hilton Head, SC,
Jun. 6-10, 2004.
[15] V. Milanović, K. Castelino, “Tip-Tilt-Piston Actuators for High Fill-Factor Micromirror Arrays,”
Solid State Sensor, Actuator and Microsystems Workshop, Hilton Head, SC, Jun. 6-10, 2004.
[16] Veljko Milanović, Kenneth Castelino, Daniel McCormick, “Fully-Functional Tip-Tilt-Piston Micromirror
Array," 2006 IEEE/LEOS Optical MEMS and Their Applications Conf., Big Sky, Montana, Aug. 21, 2006.
[17]Veljko Milanović, Kenneth Castelino, Daniel McCormick, “Highly Adaptable MEMS-based Display with Wide
Projection Angle," 2007 IEEE Int. Conf. on Microelectromechanical Systems (MEMS'07), Kobe, Japan, Jan. 25,
2007.
[18] Veljko Milanović, “Improved Control of the Vertical Axis Scan for MEMS Projection Displays ,"
submitted to: 2007 IEEE/LEOS Optical MEMS and Their Applications Conf., Hualien, Taiwan, Aug. 12, 2007.
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Thank you for your attention!
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Appendix
 MEMS Dewvices
 Fish eye wide-angle lens
 optical scan angle 128o
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Appendix
Adriatic Research Institute
ARI Services :
 Custom Microfabrication Services
(1) 4” and 6” Wafers for CMOS and MEMS
(2) Diffusion ,Oxidatin, Depostion
(3) Etching
a. DRIE
b. RIE
c. Plasma Etching
d. XeF2 Etching
(4) E-Gun for W, Al, Cr, Au
 Consulting
CMOS and MEMS with 6 years experiences
 Contract Research and Development
ARI Micromirror Development(MPG FilE) :
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Transformer rotations
The transformers allow larger static rotations of the micromirror
IEEE JOURNAL OF SELECTED TOPICS IN QUANTUM ELECTRONICS, VOL. 10, NO. 3, MAY/JUNE 2004
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