04147576.pdf

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JOURNAL OF MICROELECTROMECHANICAL SYSTEMS, VOL. 16, NO. 2, APRIL 2007

Simple Fabrication Process for Self-Aligned,

High-Performance Microscanners—

Demonstrated Use to Generate

a 2-D Ablation Pattern

Hyuck Choo, David Garmire, James Demmel

, Fellow, IEEE

, and

Richard S. Muller

, Life Fellow, IEEE, Member, ASME

Abstract—

A new, straightforward, complementary metal–

oxide–semiconductor (CMOS)-compatible, three-mask process

is used to fabricate high-performance torsional microscanners

driven by self-aligned, vertically offset comb drives. Both the

moving and fixed combs are defined using the same photolithog-

raphy mask and fabricated in the same device layer, a process

allowing the minimum gap between comb fingers to be as small

as twice the alignment accuracy of the photolithography process.

Our fabricated microscanners have torsional resonant frequencies

between 58 Hz and 24 kHz and maximum optical-scanning angles

between 8



and 48



with actuation voltages ranging from 14.1

to 67.2

V

rms

. The yields on two separate fabrication runs have

been better than 70%. To demonstrate an application for these

scanners, we used them to generate laser-ablation patterns suitable

for ocular cornea surgery. We assembled a 2-D scanning system

by orienting two identical microscanners at right angles to one an-

other. When driven by two 90



out-of-phase 6.01-kHz sine waves,

the cross-coupled scanners produce circular patterns having radii

fixed by the amplitude of the driving voltage. Then, we emulated

a small pattern from the surface topography found on a U.S.

Roosevelt dime and built up an ablation pattern that compares

favorably with similar emulations reported by earlier researchers

who used larger, more complicated ablation systems. [2006-0185]

Index

Terms—

Complementary

metal–oxide–semiconductor

(CMOS)-compatible, ocular refractive surgery, self-aligned ver-

tical offset combs, torsional microscanners, 2-D scanning system.

I. I

NTRODUCTION

ANY researchers have been motivated to develop

simpler, more cost-effective scanner-fabrication tech-

nologies because the commercial markets that have resulted

from the macroscale torsional scanner (galvano-scanner)

technology are mature and lucrative. The scanners are la-

beled “torsional” because they consist of mirrors supported

by beams that are torsionally flexed in order to direct a light

beam through an arc. Scanners are essential components for

applications such as optical switches in telecommunication

Manuscript received August 31, 2006; revised November 22, 2006. Parts

of this paper were presented orally at the 2005 IEEE/LEOS Optical MEMS

Conference, Technical Digest 21-22, Oulu, Finland, August 1-4, 2005. This

work was supported by the National Science Foundation under the Grants NSF-

EEC0318642 and CITRIS-NSF-TR22325. Subject Editor H. Fujita.

The authors are with the Electrical Engineering and Computer Sciences De-

partment, University of California at Berkeley, Berkeley, CA 94720-1774 USA

(e-mail: hchoo@eecs.berkeley.edu).

Digital Object Identifier 10.1109/JMEMS.2007.895048

networks [1], high-definition and retinal displays for entertain-

ment, engineering, and educational markets [2]–[5], barcode

scanning for inventory monitoring, endoscopic, confocal, and

coherent tomography imaging in biomedical fields [6]–[8],

range-finding systems for safe vehicular navigation, and free

space laser communications [9]

A number of previous researchers have used the methods

that are generally identified as “microelectromechanical system

(MEMS) technologies” to fabricate microscanners in order to

exploit the precise design and mass production advantages af-

forded by this choice. Specific results as reported for earlier re-

search demonstrate, however, that there are pitfalls that lead to

undesirable complexity, lowered processing yields, and other

difficulties. A major problem area is centered on actuation of

the microscanners.

Torsional microscanners typically require substantial torque

and to produce this torque by electrostatic drivers, previous re-

search [10] has shown the effectiveness of using vertically offset

comb pairs for the drivers. Fabrication of these vertically offset

combs has been a considerable challenge to earlier MEMS tech-

nologists, who have found the solutions using the following

demanding procedures: 1) carrying through critical alignment

steps in a two-wafer process [10], 2) controlling and replicating

the properties of materials such as photoresist or bimorph layers

so that these materials can function as hinges [11], 3) postpro-

cess annealing in a high-temperature furnace following the hand

assembly of lids on device chips [12], and 4) depositing mul-

tiple-masking layers (composed of silicon dioxide and silicon

nitride) [13] to create the offset combs. We decided to focus our

research on the development of fabrication methods that would

produce vertically offset comb pairs using more conventional

integrated-circuit (IC) processing tools.

This paper reports a complementary metal–oxide–semicon-

ductor (CMOS)-compatible MEMS technology that we have

developed and demonstrated for batch-fabricating high-perfor-

mance torsional microscanners. Our microscanner-fabrication

technology employs only conventional silicon-processing

tools that have proven their effectiveness and user-friendliness

through large scale use in the integrated circuits industry. The

required temperatures for all of our processing steps are low

enough to allow prefabrication of CMOS electronics directly

on the same wafer as the microscanner devices. The yield for

this new scanner process has exceeded 70% on two fabrication

CHOO

et al.

: SIMPLE FABRICATION PROCESS FOR SELF-ALIGNED, HIGH-PERFORMANCE MICROSCANNERS

261

Fig. 1. Three different microscanner designs: (a) fast microscanner with a circular scanning area (or optically re

ective area); (b) very fast microscanner with

a rectangular scanning area; and (c) slow microscanner with an extra large scanning area; inset at lower right is a plan view showing the dimensions of t

he mi-

croscanner support beams.

runs (

116 devices per wafer, 2 wafers per run

) made in the

University of California at Berkeley Microlab.

Operational tests on the fabricated microscanners show that

they easily meet the performance requirements for many ap-

plications in the biomedical, telecommunication, and imaging

systems areas. To demonstrate the microscanner performance,

we have investigated a particular application for which we

our design to be well suited: refractive laser surgery of ocular

corneas where small spot size and high scan speeds are im-

portant assets [14]. In ocular refractive surgery, surgeons need

to steer and control laser pulses to reshape a patient

’

s corneas

in order to improve his vision. To demonstrate this use with

our microscanners, we have employed them to generate abla-

tion

–

emulation results that are superior to published emulation

patterns that had been produced by commercial, state-of-the-art

eye-surgery microscanners [14].

There are potentially many additional MEMS applications

for the robust, high-performance comb drivers introduced in

this paper. As a result of their fabrication using only conven-

tional IC processing tools, there is excellent control of critical

dimensions such as comb-

nger spacings. These spacings are

determined by a single photomasking step which allows them

to be as small as two times the alignment accuracy of the pho-

tolithography process (which is 2

7nm

14 nm for Nikon

NSR-S609B). However, the practical minimum gap sizes are

typically 1

m wide or larger because they are determined by

the fabrication process limitations and variations such as an

achievable aspect ratio of a deep reactive ion etching (DRIE)

process as well as the sidewall erosions commonly observed

in plasma-etch processes. Minimizing gap spacing reduces the

driving voltage needed to provide a given force. As an example,

we consider a typical design in which vertical combs having

gaps of 3

m, widths of 5

m, and lengths of 100

m, are laid

out using 25% of the comb-drive area for supporting structures.

With this design,

nished combs will exert an out-of-plane force

density of 13.8

N/cm

. Comb drives having this force den-

sity can be used advantageously in many ways; for example, in

adaptive optics for mirror-curvature adjustments [15], in vertical

inch-worm motors [16], in phase-shifting interferometers [17],

and also, in acoustic speakers. In yet another application, by pro-

ducing a capacitance change of 27.6 pF/cm

per micrometer of

out-of-plane motion, the combs can gainfully be applied to the

design of

-axis accelerometers, to innovative microphone tech-

nologies and to microstage positioning systems.

II. D

ESIGN

ABRICATION

AND

HARACTERIZATION

A. Microscanner Design

We have investigated three different designs of microscanners

as pictured in Fig. 1.

For each of these three designs, we have varied the dimen-

sions (diameters of circular re

ective areas or lengths and

widths of rectangular re

ective areas) of the optically re

ective

areas as along with the lengths and the widths of the torsion

beams. To predict the resonant frequencies of these designs,

we calculate the torsional stiffness of the beams using Timo-

shenko

’

s equation [18]

(1)

In (1),

is the torsional modulus for silicon, and

and

are the width and height of the beam, as indicated in the bottom-

right inset of Fig. 1. The microscanner resonant frequency is

given by

(2)

where

is the mass-moment of inertia of the microscanner

(given in Table II), the value of which depends on the mi-

croscanner geometry and is readily calculated [19].

Table I lists the dimensions of the microscanner embodiments

investigated and their predicted resonant frequencies [using (2)].

By making various combinations of re

ective areas of different

sizes and torsion beams of differing dimensions (resulting in

different torsional stiffnesses) as listed in Table I, we designed

microscanners having predicted resonant frequencies ranging

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JOURNAL OF MICROELECTROMECHANICAL SYSTEMS, VOL. 16, NO. 2, APRIL 2007

TABLE I

ARAMETER

ARIATIONS FOR

ICROSCANNER

MBODIMENTS

Fig. 2. Fabrication process for torsional microscanners with self-aligned, vertically offset combs. The left column shows top views while the right

column shows

cross-sectional views along the dotted lines following completion of the processing steps described in Section II-B.

CHOO

et al.

: SIMPLE FABRICATION PROCESS FOR SELF-ALIGNED, HIGH-PERFORMANCE MICROSCANNERS

263

Fig. 3. Etch methods to produce offsets to the comb

ngers using (a) anisotropic silicon etch and (b) oxide layer and isotropic silicon etch.

Fig. 4. SEM images of moving- and

xed-comb

ngers after completing fabrication step f) [Fig. 2(f)]. The upper two images show offset combs being processed

on SOI wafers with a 30-



m device layer (offset height: 15



m) while the lower two images show offset combs being processed on SOI wafers with a 50-



device layer (offset height: 25



m).

Fig. 5. SEM images of moving- and

xed-comb

ngers after HF release [process step g)]. The completely processed comb

ngers have sharp, well-de

ned

rectangular shapes with very smooth surfaces, regardless of having undergone the silicon isotropic etch step or not.

Fig. 6. The 3-D pro

le measurements of vertically offset combs and the uni-

formity of offset heights at

ve locations on a 10-cm processed wafer: The mea-

surements were made at its center and at locations, 2 cm from the outer edge of

the wafer. The values are peak-to-peak deviations from the average value.

TABLE II

EVIATION

ROM THE

VERAGE

ALUE

(15



from 50 Hz to 26 kHz. This wide range of resonant frequencies

can address the requirements for microscanners having many

different applications.

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JOURNAL OF MICROELECTROMECHANICAL SYSTEMS, VOL. 16, NO. 2, APRIL 2007

Fig. 7. SEM pictures of fabricated microscanners: (a) fast circular microscanners

—

only LTO has been used in the fabrication process and (b) very fast rectangular

microscanners

—

only thermal oxide has been used in the fabrication.

TABLE III

ESONANT

-M

OTION

ROPERTIES OF

EPRESENTATIVE

ICROSCANNERS

Fig. 8. Frequency response of selected microscanners with circular re

ective

areas.

Fig. 9. Ocular refractive surgery: Using a microkeratome (a very

ne blade),

a corneal

ap is cut open. Then, using a laser (wavelength: 193

–

208 nm), the

exposed inner tissue of the cornea is selectively ablated to correct optical aber-

rations and thereby improves the patient

’

s vision.

B. Microscanner Fabrication

The microscanner fabrication process, which involves the use

of three photolithography masks [two for de

ning features in

the device layer of a silicon-on-insulator (SOI) wafer and one

for opening the backside of the microscanners], is illustrated in

Fig. 2. The following is true.

a) We start with a

-type SOI wafer (device-layer

thickness: 30 or 50

m, resistivity: 0.005

–

0.01

cm) and

grow 0.5-

m thermal oxide at 900

C or deposit low-

temperature oxide (LTO) at 400

C. LTO must be chosen if

it is necessary to ensure that the fabrication process remains

completely CMOS-compatible. Because the oxide layers

serve only as protective layers, the LTO layer does not need

to go through a densi

cation process at high temperatures

(which would typically exceed 950

C). Next, using the

photolithography mask #1, we pattern and remove the

CHOO

et al.

: SIMPLE FABRICATION PROCESS FOR SELF-ALIGNED, HIGH-PERFORMANCE MICROSCANNERS

265

Fig. 10. Summary of ablation process for refractive surgery: (a) only that part of the laser pulse having energy density above an ablation-threshold v

alue will ablate

the target; (b) no ablation performed; (c) ablation pattern generated by applying a single laser pulse having the pulse-energy distribution shown in

(a); (d) ablation

pattern generated by applying two subsequent laser pulses; and (e) spherical pro

le generated by applying multiple, coordinated laser pulses.

oxide (thermal or LTO) selectively where

xed combs

will be later fabricated and vertically thinned [Fig. 2(a)].

b) Using mask #2, we de

ne patterns for the microscanners,

including moving/

xed combs,

exures, and the geome-

tries of the re

ective area, on the top surface of the device

layer [Fig. 2(b)]. The

xed combs must be de

ned within

the windows from which the oxide has been removed to

expose the silicon surface in the previous step, and the

minimum gap between the moving and

xed-comb

gers can be as small as twice the alignment accuracy of

the photolithography system.

c) After hard-baking the patterned photoresist at 120

C for

one hour, we

rst perform anisotropic oxide etch, and

then, use DRIE to pattern the microscanner structures (in-

cluding the optically re

ective area, comb

ngers, and

exures) in the device layer of the SOI wafer [Fig. 2(c)].

d) Once the DRIE etching is complete, we remove the pho-

toresist layer and deposit a very thin layer (

0.2

of thermal oxide or LTO, in order to stop erosion of the

sidewalls of the structures that were created in the pre-

vious step [Fig. 2(d)]. After this thin oxide has been de-

posited, there are 0.2-

m-thick oxide layers on top of

the

xed-comb

ngers and approximately 0.7-

m-thick

oxide layers on all other surfaces including, especially, the

top surfaces of the movable comb

ngers and of optically

ective surfaces.

e) Following the oxide growth (or deposition), we perform

a timed anisotropic-plasma-oxide etch to remove the

0.2-

m-thick oxide from the top-facing surfaces. This

step exposes the silicon surface on top of the

xed combs,

but leaves all other surfaces covered by an approximately

0.5-

m-thick oxide layer [Fig. 2(e)].

f) In a next step, we use a timed plasma etch that erodes

silicon isotropically to etch the exposed top surfaces of

the

xed combs, thinning only these

ngers because all

other surfaces of the structures are still protected by an

oxide layer [see Figs. 2(f), 3(b), and 4].

g) The, using mask #3, we pattern and open the backside

of the microscanners, and release the devices in con-

centrated high-frequency (HF) followed by critical point

drying (CPD) [Fig. 2(g)].

Comment on the need for steps d) and f), thin-oxide deposi-

tion and selective removal

: In theory, the previously described

process might be simpli

ed through omission of steps d)

–

f), re-

placing them by an anisotropic etch which should erode only the

exposed

xed-comb tops. In practice, we have found, however,

Fig. 11. The 2-D scanning system realized using a pair of identical micro-

scanners.

that anisotropic silicon etch does, in fact, erode surfaces that are

not perpendicular to the beam causing considerable silicon re-

moval from the comb sidewalls.

This erosion leads to unacceptable control of comb-

nger

widths and of the gaps separating the

ngers. Accordingly, we

have added the thin-oxide deposition and selective removal

steps to produce our microscanners.

Fig. 4 shows scanning electron microscope (SEM) images of

moving- and

xed-combs taken immediately following comple-

tion of the timed-isotropic silicon etch described in process step

f) and shown in Fig. 2(f). The vertically etched top surfaces as

well and the remaining oxide shells are clearly visible. Com-

pressive stress in the silicon dioxide layer is the source for the

waviness of the vertical oxide shell. The oxide waviness does

not have any effect on the

nal shape of the silicon comb

gers, as shown in Fig. 5.

Fig. 5 shows SEM images of released combs [following step

g)]; the comb

ngers are clearly vertically offset, sharply de-

ned, and precisely aligned. The top surfaces of the isotropi-

cally etched

xed-comb

ngers are visually as smooth as the

surfaces of the adjacent unprocessed comb

ngers that form the

moving-comb pair.

Using a WYKO NT3300 optical surface pro

ler, we mea-

sured the offset heights of vertically offset comb

ngers around

the wafers. The measurements were made at

ve locations,

2 cm from the outer perimeter of 10-cm processed wafers

(Fig. 6). The peak-to-peak deviations at

ve locations shown

266

JOURNAL OF MICROELECTROMECHANICAL SYSTEMS, VOL. 16, NO. 2, APRIL 2007

Fig. 12. Schematic diagram of experimental setup using scanners to generate cornea ablation patterns.

Fig. 13. Stability and repeatability of our 2-D scanning system within 30 min.

in Table II are smaller than the thickness

uctuations found

stated in the speci

cations for the device layers of SOI wafers

(typically 0.5

–

m), and they show excellent uniformity for

the new process.

C. Fabricated Microscanners

SEM pictures of fabricated microscanners are shown in

Fig. 7.

Our fabrication process has produced high yields on two sep-

arate fabrication runs (116 micromirrors per wafer, two wafers

per run). Between 70% and 85% of tested microscanners per-

form properly on all of the wafers. Damages to microscanners

mostly occurred during step g), the

nal HF-release/rinsing/crit-

ical-point-drying step as a consequence of rough handling.

Table III shows the resonant frequencies

, quality factors

, and maximum optical scan angles (OSA) at resonance

measured for selected microscanners driven with sine waves

having the tabulated root-mean-square (rms) amplitudes. Here,

OSA is de

ned as an angle that is twice the mechanical scan

angle that a microscanner physically rotates. Resonant fre-

quencies of the fabricated microscanners ranged from 58 Hz to

24 kHz. The maximum resonant amplitudes achieved by the

microscanners ranged from 8

to 48

, with most microscanners

exhibiting OSA of 20

. The actuation voltages ranged

from 14.1 to 67.2

. Fig. 8 shows the frequency response

measured for

ve different microscanners.

D. Microscanner Application Example: Emulating A Cornea

Ablation Process

In order to evaluate our microscanners in a

“

real-world

”

ap-

plication, we investigated their possible application to the task of

refractive laser surgery of ocular corneas. Scanners used for this

purpose should be effective in steering very small laser beams at

high scan speeds [14]. The purpose of the surgery is to reshape

optical corneas by ablating tissue in order to correct optical aber-

rations as shown in Fig. 9.

Ablation of human corneas is a cumulative process, as shown

in Fig. 10. Only the section of the laser pulse having an energy

level higher than the threshold value (50

–

60 mJ/cm

) causes ab-

lation [14], [20]. The depth of the ablated tissue is proportional

to the logarithm of the laser-pulse energy [20].

To demonstrate this application, we assembled a 2-D scan-

ning system by orienting two identical microscanners at right

angles to one another as shown in Fig. 11 (mirror #3 in Fig. 8,

mirror diameter

1 mm, resonant frequency

6.01 kHz) and

scanned a pulsed laser beam (670-nm wavelength). The cross-

coupled scanners were driven by two 6.01-kHz sine waves that

were 90

out of phase, producing circular patterns having radii

xed by the amplitude of the driving voltage with an intensity

governed by the modulated laser (Fig. 12). For cornea abla-

tion, circular scanning provides for an excellent match to the

cornea

’

s geometry and is, therefore, favorable over the more

typical raster scanning which uses linear sweeps by horizontal-

and vertical-scanning mirrors to trace out a pattern.

In the ablation system, laser spots forming the pattern persist

for 0.4

s and have a 220-

m diameter (full width/half max-

imum) as measured with a charge coupled devices (CCD) op-

tical sensor. The wavelength of the laser is 660 nm. A CCD

sensor, positioned in place of the ocular cornea, allows us to as-

sess performance of the system. As mentioned earlier, refractive

laser surgery is a cumulative ablation process [14]. To mimic the

real process, we capture the scanning pattern at each CCD frame

and then sum the intensity pro

les which are proportional to the

nal ablation pattern. The usual period of time for optical laser

surgery is shorter than 20 min so we measured the repeatability

and stability of our system over a period of 30 min (Fig. 13).

Our system demonstrates excellent repeatability in pulse posi-

tion (standard deviation less than 0.56

m) as well as in pulse

diameter (standard deviation less than 0.68

m) around the ab-

lation zone.

To demonstrate the versatility of our area scanner, we have

emulated a small pattern from the surface topography found on a

U.S. Roosevelt dime. The 3-D topology of the region of interest

on the United States dime was measured using a WYKO NT3300

and is shown in Fig. 14(b) and (c) as well as in Fig. 15(a). The

height information was then converted into a grayscale image

–

255 level), which is easier to utilize for ablation process.

CHOO

et al.

: SIMPLE FABRICATION PROCESS FOR SELF-ALIGNED, HIGH-PERFORMANCE MICROSCANNERS

267

Fig. 14. Selected ablation target pattern: (a) picture of a United States dime; (b) 3-D pro

le of the region of interest indicated by the dotted circle (measurements

by using WYKO NT 3300); and (c) 3-D pro

le converted to a grayscale image (based on height information), which is more convenient for emulating the ablation

process.

Fig. 15. (a) WYKO 3-D surface pro

le [Fig. 14(b) repeated]. (b) The 3-D di-

agram of small-spot ablation replica of the dime surface captured by our mi-

croscanner and CCD system (peak-to-valley height difference is approximately



m on the original surface).

Fig. 16. Laser-ablation pattern produced by a commercially available system:

(a) surface topology of a United States penny (target pattern); (b) reproduced

pattern using a state-of-the-art refractive surgery system; (c) magni

ed image

zoomed in around the ear of the reproduced pattern (after [14]). Fig. 15(b) can be

compared to Fig. 16(c) for an evaluation of performance of our ablation scanning

system with the performance of a commercial system (VISX STAR S4).

Next, according to the grayscale image, we have built up an

ablation pattern over a 40-min interval. The resultant pattern is

shown in Fig. 15(b). Because the scanning spot was 220

min

diameter, some of the very

ne details were lost. Yet, overall,

the emulated ablation image contains many details and shows

good-quality depiction of the original target pattern.

Fig. 16 shows a similar result presented by researchers to

demonstrate their ablation capabilities using a state-of-the-art

refractive surgery system [14]. By comparing Fig. 15(b) with

the images shown in Fig. 16(b) and (c), we can judge at least

qualitatively that the microscanner ablation system that we have

presented performs very well as compared to presently available

macrosized tissue-ablation systems.

III. C

ONCLUSION

We have designed, fabricated, and tested microscanners

using our new fabrication techniques. The process uses

well-developed integrated-circuit processing tools, and is

simple, high yielding, and reliable. The major advance in our

fabrication process results from its straightforward method to

produce vertically offset comb pairs that provide for robust

electrostatic drive of torsion-bar suspensions. In practice,

we achieve uniform offset heights for vertical comb

ngers

processed across the 10-cm wafers. We have produced mi-

croscanners having resonant frequencies ranging from 50 Hz

to 24 kHz having OSA values typically approximating 20

but

varying from 8

to 48

. The actuation voltages required were

from 14.1 to 67.2

A 2-D scanning system, built using these microscanners, pro-

duced emulated ablation patterns that compare favorably to re-

sults published by researchers to illustrate the performance of a

state-of-the-art macroscale ablative surgery system.

CKNOWLEDGMENT

The authors would like to thank M. Wasilik of University

of California Berkeley Microlab for developing silicon etch

recipes and Dr. M. Helmbrecht of Iris Adaptive Optics (I. AO,

Berkeley, CA) for the loan of a high-voltage ampli

er.

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268

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”

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Boston, MA, Jun. 2002, pp. 1015

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comb-drive actuated trussed scanning mirrors,

”

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Int. Conf. Opt. MEMS Their Appl.

, Aug. 2003, pp. 12

–

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, Aberration-Free Refrac-

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terlaken, Switzerland, Feb. 2002.

Hyuck Choo

received the B.S. and M.Eng. degrees in

1996 and 1997, respectively, in electrical engineering

from Cornell University, Ithaca, NY. He is currently

working towards the Ph.D. degree in electrical engi-

neering and computer sciences at the University of

California, Berkeley (UC Berkeley), under Prof. R.

S. Muller

’

s supervision.

Before enrolling at UC Berkeley, he was with

Kionix, Inc., Ithaca, NY, as a MEMS Test Engineer.

He has focused his research on microlens and

microscanner systems, particularly on applications

to ocular-refractive surgery, biomedical-imaging systems, high-de

nition

displays, and next-generation wavefront sensors. His most recent projects

are directed toward the development of fast MEMS-based phase-shifting

interferometers and their applications to the measurement of transient optical

and biological phenomena.

Mr. Choo won the UC Berkeley EECS Lim Prize in 2001 (Best Performance

on the Pre-Doctoral Exam) and is the two-time winner of the Berkeley Sensor

and Actuator Center presentation award.

David Garmire

received the B.S. degrees in both

computer science and mathematics from Carnegie

Mellon University, Pittsburg, PA. He is currently

working towards the Ph.D. degree in computer

science at the University of California, Berkeley (UC

Berkeley) under the guidance of Prof. J. Demmel.

His main research area is in scienti

c computing

focusing on MEMS simulation platforms, MEMS

metrology techniques, and precision-control/sensing

of MEMS devices using computers and high-speed

analog/digital electronics. He has three United States

international patents pending in MEMS photonics and sensors.

Mr. Garmire currently holds a Siebel Scholars Fellowship.

James Demmel

’

–

’

–

’

02) is the Dr.

Richard Carl Dehmel Distinguished Professor of

Computer Science and Mathematics at the University

of California, Berkeley (UC Berkeley). His personal

research interests are in numerical linear algebra,

high-performance computing, computer-aided de-

sign for MEMS, and applications of information

technology to solve societal scale problems. He

is best known for his work on the LAPACK and

ScaLAPACK linear algebra libraries.

Prof. Demmel is a Fellow of the Association for

Computing Machinery (ACM) and Member of the National Academy of Engi-

neering. He is a winner of the Society for Industrial and Applied Mathematics

(SIAM) J. H. Wilkinson Prize in Numerical Analysis and Scienti

c Computing,

He was an invited speaker at the 2002 International Congress of Mathematicians

and the 2003 International Congress on Industrial and Applied Mathematics.

Richard S. Muller

’

–

’

–

’

–

’

–

’

97) received the mechanical engineer

’

s degree

from Stevens Institute of Technology, Hoboken, NJ,

the M.S. degree in electrical engineering and the

Ph.D. degree in electrical engineering and physics,

in 1962, from the California Institute of Technology,

Pasadena.

After employment as a Member of the Technical

Staff at Hughes Aircraft Company, he joined the fac-

ulty at the University of California, Berkeley, where

he concentrated his research on the physics of inte-

grated-circuit devices. Together with Dr. T. I. Kamins of Hewlett-Packard Com-

pany, he

rst published,

Device Electronics for Integrated Circuits

in 1977. A

third edition of this book (which has been translated into

ve languages) was

published in 2003. In the late 1970s, he began research in the area now known

as MEMS and, together with R. M. White, he founded the Berkeley Sensor and

Actuator Center in 1986. His present research focus is on optical MEMS. His

present research focus is on optical MEMS.

Dr. Muller wrote the proposal to establish the IEEE/ASME J

OURNAL OF

ICROELECTROMECHANICAL

YSTEMS

(JMEMS), of which he is now the

Editor-in-Chief. A member of the U.S. National Academy of Engineering, he

received a career MEMS Award at TRANSDUCERS

’

97 as well as the IEEE

Brunetti Award (1998, with R. T. Howe), a Fulbright Professorship, and a

von Humboldt Research Award at Technische Universit

t Berlin (TU), Berlin,

Germany, in 1994. His other awards include the Berkeley Citation and the

Renaissance Award from Stevens Institute of Technology, where he served as

a Trustee from 1996 to 2005. He has been a member of the National Materials

Advisory Board and served on several National Research Council study panels

as well as chairing a 1997 panel for which he acted as Editor of a widely

distributed report on the promises and challenges of MEMS. He is a Member

of the American Society of Mechanical Engineers (ASME).