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Highly Adaptable MEMS-Based Display with Wide Projection Angle

Veljko Milanović, Kenneth Castelino, Daniel T. McCormick

Adriatic Research Institute828 San Pablo Ave., Ste. 109, Berkeley, CA 94706

MEMS 07’ p 143~146

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OutlineOutline

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large deflection angleslarge displacement

Two Basic MEMS-based projection display :Reflective displays,pioneered by Texas InstrumentDiffractive display,pioneered by Silicon Light Machines

MEMS-BASED DISPLAYMEMS-BASED DISPLAY

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2000 2001 2002 2003 2004 2005 2006 2007

[18] Improve image quality/re-flesh rate/brightness

High Temperature Operation

Display with Wide angle

Fully-Functional (high-speed /low-power)

[15] Two-Axis Scanners[7] 2 DoF linkages to a central stage.

[14] 3 DoF With Large Static Rotation and Piston Actuation

Sunghoon , Two-Axis

Research Chart Analysis

tunable field emission devices (FEDs).Torsional Micromirrors Lateral Actuators

[4]Single axis rotation

DRIE Devices

Large rotation with contact to neighboring elements

Year

Production EngineeringProduction Engineering

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A Brief History (1)

[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 10.8° and about the y-axis to 11.7°, for <85 Vdc.

Veljko Milanovic´, Member, IEEE

Year Publish Contribution

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[5] 2004 (Journal ) vertical comb drives micromachined from the back side and front side of a 50- μm silicon- on- 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

Veljko Milanovic´, Member, IEEEA Brief History (2) Year Publish Contribution

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[1]

Basic Manufacture Process

four-mask process layers with DRIE:two for front-side and two for back-side etching. High layers(50 μm)Lower layers(30 μm)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

Deep reactive ion etch (DRIE)

The biggest obstacle in SOI-MEMS mirrors is theinherent lack of out-of-plane motion.,[2001]

Three -levelVertical Comb

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Single axis rotation

out-of-wafer-plane degrees of freedom (DoF).

providing 1DoF (or single-axis) rotation

Laterally actuated ,2001

Vertical actuated ,2003

Problem: radius of curvature,dynamic deflection,Bucking

up-actuating comb drives down-actuating comb drives

high aspect ratio

Rotor & Stator2 x 2=4 TypesRotor & Stator2 x 2=4 Types

50V 100 angle50V 100 angle

9A High Aspect Ratio 2D Gimbaled Microscanner with Large Static Rotation,2002

vertical comb drives Isolation island upper-comb and Lower-Comb x rotating + Y rotating

vertical comb drives Isolation island upper-comb and Lower-Comb x rotating + Y rotating

Type 1- vertical combdrives ,2002

Two axis rotation-Vertical,islandProblem: radius of curvaturebending

x rotatingx rotating

Y rotatingY rotating

10Veljko Milanović, Int. Conf. on Microelectromechanical Systems, MEMS2004

2 generation

Type 2- vertical combdrives ,2004

Two axis rotation-Vertical,rotation transformer

Rotation transformer Mechanism

Comb drive single-axis+ single-axis unidirectional rotation

low voltage large displacement

11[19 ]D. T. McCormick, 2004 Solid State Sensor,Actuator and Microsystems Workshop

3 DoF tip-tilt-piston actuators

3 generation( Three axis rotation)

Linkage + Rotation transformer

Stator Rotor

12[16] D. T. McCormick ,2006 IEEE/LEOS Optical MEMS

Backside silicon micromirrors four vertical combdrive rotators

fully assembled four elements being driven by the software

1.2mm

Micromirrors fully assembled

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SummarySummary

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 DRIE

Vertical combdrive sets 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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ReferanceReferance(1)(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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[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.

ReferanceReferance(2)(2)

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Thank you for your attention!

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MEMS Dewvices Fish eye wide-angle lens optical scan angle 128o

AppendixAppendix

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AppendixAppendixAdriatic 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) : H:\¼B¦¨½å ¦Ñ®v\ARI Large Micromirrors.mpg

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IEEE JOURNAL OF SELECTED TOPICS IN QUANTUM ELECTRONICS, VOL. 10, NO. 3, MAY/JUNE 2004

The transformers allow larger static rotations of the micromirror

Transformer rotations