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JOURNAL OF MICROELECTROMECHANICAL SYSTEMS, VOL. 13, NO. 4, AUGUST 2004
An In-Plane High-Sensitivity, Low-Noise Micro-g
Silicon Accelerometer With CMOS Readout Circuitry
Junseok Chae, Member, IEEE, Haluk Kulah, Member, IEEE, and Khalil Najafi, Fellow, IEEE
Abstract—A high-sensitivity, low-noise in-plane (lateral) capacitive silicon microaccelerometer utilizing a combined surface and
bulk micromachining technology is reported. The accelerometer
utilizes a 0.5-mm-thick, 2.4 1.0 mm2 proof-mass and high aspect-ratio vertical polysilicon sensing electrodes fabricated using a
trench refill process. The electrodes are separated from the proofmass by a 1.1- m sensing gap formed using a sacrificial oxide layer.
The measured device sensitivity is 5.6 pF/g. A CMOS readout cirmodulator opcuit utilizing a switched-capacitor front-end
erating at 1 MHz with chopper stabilization and correlated double
sampling technique, can resolve a capacitance of 10 aF over a dynamic range of 120 dB in a 1 Hz BW. The measured input referred noise floor of the accelerometer—CMOS interface circuit
is 1.6 g/ Hz in atmosphere.
[1115]
6 1
Index Terms—Inertial sensors, micromachined accelerometer,
micro-g, sigma-delta, switched-capacitor.
Fig. 1. Performance
microaccelerometers.
I. INTRODUCTION
H
IGH-PRECISION microaccelerometers are increasingly
needed in inertial navigation/guidance, unmanned aerial
vehicles (UAV’s), seismometry, and space microgravity applications because of low-cost, small-size, and low power dissipation. Many transduction techniques and several devices with
10’s of micro-g resolution have been reported. Capacitive accelerometers have been commonly used due to several advantages such as high-sensitivity, low-noise, stable dc characteristics, low-power dissipation, and low-temperature sensitivity [1].
Fig. 1 summarizes the noise performance of some of the reported in-plane (x- and y-axis) and out-of-plane (z-axis) micromachined accelerometers. Note that the noise floor in the figure
indicates not just mechanical noise, but overall accelerometer
system noise. In this paper, noise represents the overall system
noise unless it is stated as mechanical or electronic noise. Most
of the reported high performance devices are sensitive to out-ofplane (vertical, z-axis) acceleration since it is easier to fabricate large proof-mass and large-area electrodes along the z-axis.
These sensors utilize full wafer thickness for their proof-mass,
and a small sensing gap [2], [3]. Those characteristics (large
proof-mass, large-area electrodes, and a small sensing gap) enable these out-of-plane accelerometers to achieve high sensitivity and low noise performance. However, it is not easy to
Manuscript received July 17, 2003; revised December 18, 2003. This
work has been supported by DARPA under Contract F30602-98-2-0231.
This work made use of the WIMS Engineering Research Center’s Shared
Facilities supported by the National Science Foundation under Award Number
EEC-0096866. Subject Editor E. Obermeier.
The authors are with the Department of Electrical Engineering and Computer Science, Center for Wireless Integrated Microsystems, The University of
Michigan, Ann Arbor, MI 48109-2122 USA (e-mail: [email protected]).
Digital Object Identifier 10.1109/JMEMS.2004.832653
improvements
for
In-plane
and
Out-of-plane
achieve these features for in-plane (lateral, x-, y-axis) sensors
that are sensitive to acceleration parallel to the sensor substrate
because of the difficulty in fabricating high-aspect ratio vertical
sense/drive electrodes with small sensing gaps. Although surface micromachined accelerometers can be integrated with interface electronics to improve performance, due to their small
mass they typically have a noise floor of 0.03–1 mg/ Hz at atmospheric pressure [4]–[8]. Although vacuum packaging substantially reduces the mechanical noise of a surface micromachined accelerometer and lowers the output noise floor, it is
desirable to operate sensors in atmosphere since vacuum packaging is not cost effective [6].
In order to increase the proof-mass size above what is
typically achievable using surface micromachining, silicon-on-insulator (SOI) or wafer-bonded accelerometers
utilizing deep-reactive ion etching (DRIE) technology have
been developed [9]–[12]. These accelerometers utilize a 25–120
m thick single-crystal silicon proof-mass to reduce overall
system noise. However, most of these accelerometers either do
not provide high enough resolution needed for inertial-grade
performance, or have complicated fabrication processes and
large parasitics. In this paper we report a high-sensitivity,
low-noise in-plane silicon accelerometer which utilizes a
full wafer thickness proof-mass, high aspect-ratio electrodes,
and small conformal sensing gaps using a combined surface
and bulk micromachining technology [13]. In the following
sections, the structure of the proposed accelerometer, its fabrication and associated process issues, and measurement results
of the accelerometer—CMOS system will be presented.
1057-7157/04$20.00 © 2004 IEEE
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CHAE et al.: AN IN-PLANE HIGH-SENSITIVITY, LOW-NOISE MICRO-g SILICON ACCELEROMETER
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TABLE I
GAIN/NOISE RATIO COMPARISON BETWEEN OUT-OF-PLANE AND IN-PLANE ACCELEROMETERS
II. SENSOR DESIGN
A. Approach
An acceleration sensor module consists of a micromachined
accelerometer and readout electronics. Although both mechanical noise from the accelerometer and the readout electronics
noise contribute to the overall noise, the electronic noise is dominant unless the module has significantly large gain and large
mechanical noise [6]. In order to achieve a low noise system, the
mechanical noise should be small, and the gain of the module
should be large. The gain of the module consists of two parts;
gain of the accelerometer (defined as output/input acceleration)
and that of the electronics. As the electronics gain increases,
however, electronic noise increases [14]. Thus, the overall noise
floor is heavily dependent on the gain of the accelerometer.
In order to obtain high-gain, low-noise capacitive microaccelerometers, it is necessary to reduce damping, increase proofmass size, and reduce the sensing gap [13]. The Gain/Mechanical noise ratio of a capacitive accelerometer in atmosphere with
squeeze film damping is
(1)
where is the number of sense electrodes, is the sensing gap,
is the thickness of the proof-mass, is the spring constant,
and
and
are the length and height of the sense electrodes, respectively. As shown in (1), increasing the thickness
of the proof-mass is the most effective means to obtain large
Gain/Mechanical noise ratio.
There have been many reports of micromachined accelerometers in the literature to achieve high gain and low noise performance. Out-of-plane sensors, typically, provide higher gain and
lower noise floor than in-plane devices because they have much
larger proof-mass and smaller sensing gap with larger sense
area. Table I summarizes the characteristics of commercialized
or in-development out-of-plane and in-plane accelerometers.
Due to the small mass and the relatively large sense gap with
small sense capacitance, surface micromachined accelerometers
have lower gain compared to other accelerometers, which results in higher system noise. In order to overcome this drawback,
a SOI accelerometer has been developed [9], [11]. It offers much
larger mass and sense capacitance, which provide high gain and
low noise floor. However, still the Gain/Noise floor ratio is small
compared to that of out-of-plane devices.
A bulk micromachined accelerometer provides relatively
large mass compared to other lateral devices [10], [12]. Due
to its large sense gap, however, the gain is small compared
with that of out-of-plane accelerometer. This is because of
the finite lateral etch from a DRIE step. In order to achieve
truly inertial-grade high-sensitivity and low-noise in-plane
accelerometers, a new structure is needed. In this work, a
high aspect-ratio structure is developed by using a combined
surface and bulk micromachining technology; the sensing
gap is defined by a sacrificial layer, surface micromachining
technology, and a large proof-mass (wafer thick, 500 m) is
obtained utilizing bulk micromachining technology.
B. Structure
The in-plane silicon accelerometer structure is illustrated
in Fig. 2. This has a large proof-mass, stiff sense/drive electrodes, and a small and reproducible sensing gap. The silicon
proof-mass is supported using high aspect-ratio polysilicon
springs, which are formed by refilling deep-etched trenches
[15]. Polysilicon trench refilling is also used to form vertical
sense/drive electrodes, which are attached to the fixed support
rim and span the entire width of the proof-mass. The cross-section of differential capacitive sense/drive electrode pairs is
also shown in the figure. The proof-mass is released in wet
silicon etchants such as ethylene-diamine pyrocatecol (EDP).
This same etching step is used to etch the silicon around the
outside perimeter of the sense/drive electrodes as illustrated.
Unlike conventional in-plane accelerometers, the proposed
in-plane silicon accelerometer uses a bridge-type electrode
configuration.
Note that one side of the proof-mass forms the sense capacitor
with the sense/drive electrodes, while the other side is etched
and does not form a capacitor with the electrodes. This is necessary and important in order to ensure that the gain of the device
is not compromised when the proof-mass moves. Electrodes and
support beams are also formed on the bottom side of the device
to reduce cross-axis sensitivity and offset.
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630
Fig. 2.
JOURNAL OF MICROELECTROMECHANICAL SYSTEMS, VOL. 13, NO. 4, AUGUST 2004
Top view and cross section of the proposed in-plane accelerometer.
C. Stiff Sense/Drive Electrodes
Frequently capacitive accelerometers utilize force feedback
to achieve a high dynamic range and high bandwidth [16]–[18].
This feedback force is applied between two sets of sense/drive
electrodes, one attached to the substrate and the other attached
to the proof-mass. When a voltage is applied between these electrode sets, electrostatic force is generated and tends to attract the
proof-mass toward the fixed electrodes. Obviously, it is important that the sense/drive electrodes be stiff enough so as not to
bend when this force is applied. Otherwise, the feedback force
causes unstable operation [19].
Many in-plane devices use long and narrow comb finger electrodes on a relatively small proof-mass (few microgram weight,
2–50 m thickness). These long and narrow comb fingers
cannot be used if the proof-mass gets bigger—in the order of
m)—because
milli-gram weight with full wafer thick (
the fingers are not stiff enough to resist bending in the direction
of the applied force. Therefore, a more rigid configuration of
electrodes is required to ensure stable operation for the in-plane
accelerometer with large proof-mass.
The proposed in-plane accelerometer uses bridge-type
electrode configuration. The bridge electrode configuration is
much stiffer per unit length than cantilever type electrode. The
stiffness (k, spring constant) of a cantilever beam (conventional
scheme) is 64 times smaller than that of a bridge configuration
with the same mechanical dimensions for the beam [20]. Note
that the length of the sense/drive electrode is preferred to be
large in order to increase sense area which is necessary to
achieve high-gain. Since the stiffness of a beam (electrode)
(length of a beam), the sense
is inversely proportional to
electrode in a cantilever-type comb finger scheme can bend
when a large force is applied if the proof-mass becomes heavy.
The bridge-type configuration has been implemented in
out-of-plane devices using either glass wafers or polysilicon
electrodes [2], [13]. However, it is not practical to apply these
methods to in-plane devices due to inherent characteristics of
semiconductor planar fabrication techniques. In conventional
cantilever-type accelerometers, the stiffness of electrode could
be increased by increasing its width, thus effectively increasing
stiffness. But, this consumes a large area, and is not a very
effective method.
The bridge configuration electrodes are implemented by
polysilicon trench-refilled technique in the in-plane silicon
Fig. 3. Improve stiffness of electrodes by using interelectrode cross-bar
stiffeners.
accelerometer. The thickness of the sense/drive electrodes
made of polysilicon is determined by the width of trenches. The
stiffness of the electrodes is mainly limited by the thickness
of the electrodes, which is, at maximum, twice the thickness
of the deposited polysilicon layer. By simple calculation, a 2mm-long, 2.5- m-thick polysilicon, 70- m-tall bridge configuration electrode has a very small spring constant of 3.0 N/m.
In order to obtain much stiffer electrodes, two long polysilicon
plates are connected by short polysilicon connectors.
The stiffness of the electrode is simulated using ANSYS. The
electrode is 2-mm long, 70- m tall, 5- m thick, and the length
of the polysilicon connector (located every 70 m) is 10 m. A
spring constant of 1100 N/m is obtained from ANSYS simulation. The stiffness of the bridge electrode configuration can be
further increased by using cross-bar inter-electrode stiffeners as
illustrated in Fig. 3. By using these stiffeners, stable and stiff
electrodes a few millimeters long, as needed in high-gain devices, can be formed.
D. Device Specifications and Sensor System Performance
Specifications of the in-plane silicon accelerometer are summarized in Table II. Note that the estimated gain is comparable to that of out-of-plane devices while mechanical noise is
sub- g/ Hz due to large proof-mass.
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CHAE et al.: AN IN-PLANE HIGH-SENSITIVITY, LOW-NOISE MICRO-g SILICON ACCELEROMETER
631
Fig. 4. Fabrication process sequence of the in-plane accelerometer. (a) Boron doping, (b) DRIE Trench, (c) Oxide, Nitride, Poly Deposition, (d) Pattern Oxide,
Nitride, Poly, (e) Electroplate Metal, (f) Anisotropic wet etching, and (g) HF Release.
TABLE II
IN-PLANE SILICON ACCELEROMETER DESIGN SPECIFICATIONS
From the above noise calculation, the noise of the sensor system
with readout electronics is expected to be sub- g/ Hz.
III. FABRICATION
The signal from the accelerometer is read out by using a
modulator [21]. Thus, to esswitched-capacitor front-end
timate the noise floor of the accelerometer with readout circuit,
contribution from readout electronic noise needs to be taken
into account. A hybrid-assembled out-of-plane accelerometer
module, using the same readout circuit as the in-plane silicon
accelerometer system, was demonstrated with electronic noise
nV/ Hz [22]. The overall noise floor can be estimated as
(assuming 0.2 V/pF circuit gain) as follows:
Fig. 4 shows the fabrication process of the accelerometer. It is
a double-sided process (although processing can be carried out
only on one side of the wafer) that requires six masks, utilizes
silicon dioxide as a sacrificial layer, and defines device structure with anisotropic wet etching at the end of the process. This
is the same exact process used for fabricating an out-of-plane
accelerometer which has been developed by our group and does
not require any additional steps [3].
The process starts with a shallow p++ boron diffusion,
defining the proof-mass and supporting rim, on
double-side polished p-type silicon wafers. Then, 70- m-deep
trenches are etched in the silicon to be used later to form the
vertical electrodes. The trenches are then refilled completely
with oxide for a sacrificial layer, nitride, and doped polysilicon.
After polysilicon deposition, annealing is followed to alleviate
any compressive stress in the polysilicon. Next, the polysilicon
and nitride films are etched using RIE and another oxide
(capping) is deposited. The oxide is patterned to form metal
contact vias and openings to the bulk silicon for the subsequent
anisotropic wet etching. Then, contact metal is electroplated.
To minimize the anisotropic wet etching time and help undercut
the electrodes by the etchant, some of the single-crystal silicon
is etched by DRIE. After the DRIE, anisotropic wet etching is
followed not only to define the proof-mass and supporting rim
but also to etch the unnecessary silicon around the sense/drive
electrodes. This step is important since the unnecessary silicon
would reduce the capacitance change from an external acceleration resulting in gain degradation. Finally, the sacrificial oxide
layer is removed by hydrofluoric acid (HF). Critical steps and
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JOURNAL OF MICROELECTROMECHANICAL SYSTEMS, VOL. 13, NO. 4, AUGUST 2004
Fig. 6. Anisotropic wet etch around the sense/drive electrodes.
Fig. 5. Anisotropic wet etch for the proof-mass, the rim, and the sense/drive
electrodes.
their influence on the overall performance are discussed in the
following subsections.
A. Annealing
Sense/drive electrodes are made of polysilicon which has
residual stress. In order to control the stress of the film, two
annealing steps are performed. One is polysilicon in situ anenvironment at 625 C for two hours) right after
nealing (
polysilicon deposition. The other is rapid thermal annealing
environment at 1100 C for two minutes) after the
(RTA) (
final high temperature step.
Since the electrodes of the in-plane silicon accelerometer are
the polysilicon refilled inside the trenches and they are 5 m
thick, 2 mm long, it is highly desirable to have a tensile stress
in the film. By in situ annealing, the stress of the polysilicon
film is changed to be tensile (200–300 MPa) from compressive
–
MPa). The second annealing is performed after
(
the final high temperature step in order to reduce variations of
the stress over the wafer. Depending on the position inside the
polysilicon deposition furnace, the stress of the film changes
MPa) to tensile (100 MPa). RTA is
from compressive (
ambient at
performed after deposition of capping oxide in
1100 C for two minutes.
B. Anisotropic Wet Etch
Anisotropic wet etching is crucial for the in-plane silicon accelerometer. It not only defines the proof-mass and the rim by
selective etching, but also removes unnecessary silicon around
sense/drive electrodes, as illustrated in Fig. 5. A DRIE etch is
first performed to minimize the anisotropic wet etching time and
to help undercut the electrodes. Anisotropic wet etching is then
performed. Note that sense/drive sides of the electrodes are protected by a boron diffused layer while the other sides are etched
by the wet etch.
In order to remove un-needed silicon around the sense/drive
electrodes, the corrugated electrodes are at an angle with respect
direction as illustrated in Fig. 6. The wet etchant etches
to
the bulk silicon until it meets
crystal planes. Without the
Fig. 7. Top view of the in-plane silicon accelerometer.
corrugated electrodes, wet etching stops when two
planes
meet to form a V-groove. This does not remove all the unneeded
silicon from the electrodes. By properly designing the shape of
plane form
the electrodes, the wet etch continues until the
a deep V-groove below the electrodes, as illustrated.
A fabricated accelerometer and close-up views of electrodes
and polysilicon beams are shown in Fig. 7, while Fig. 8 shows
the cross section of one 70- m tall electrode and the sensing
gap of only 1.1 m. Interelectrode stiffeners to provide extra
stiffness for sense/drive electrodes are shown in Fig. 9.
IV. TEST RESULTS
A. Electrostatic Measurement
The fabricated in-plane silicon accelerometers are first tested
electrostatically. Both left and right electrodes have very simV as shown in Fig. 10.
ilar responses and pull-in voltages of
From the pull-in voltage, the spring constant of the accelerometer is obtained as 17.1 N/m (estimated 25 N/m) by (2), asis 1.1 m and (sense area) is
m . The
suming
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CHAE et al.: AN IN-PLANE HIGH-SENSITIVITY, LOW-NOISE MICRO-g SILICON ACCELEROMETER
Fig. 8.
633
Cross section of the sense/drive electrode and sensing gap.
Fig. 11. Sensitivity measurement shows 5.6 pF/g sensitivity with small offset
(0.14 pF).
Fig. 9. Interelectrodes crossbar stiffeners.
Fig. 12. Hybrid accelerometer and CMOS readout circuit module.
change according to the dividing head. It shows 5.6 pF/g (designed to be 6.8 pF/g) sensitivity with low offset (0.14 pF) and
g.
good linearity (99%) in the range of
C. Hybrid Module With Switched-Capacitor Readout Circuit
Fig. 10.
Electrostatic measurement shows pull-in voltages of
2 V.
discrepancy might be from the thickness of polysilicon springs.
Since the spring constant is very sensitive to the thickness of
), which is determined by
the springs ( is proportional to
can retrench width for refilling, only a 10% variation in
sult in changing spring constant by 30%.
(2)
B. Dividing Head (Precision Turn Table) Measurement
Devices are placed on a dividing head, precision turn-table,
to measure acceleration sensitivity. Static capacitance is mealarger than the
sured to be approximately 25 pF, which is
estimated sense capacitance of 7.7 pF. It is believed that parasitic capacitances from contact metal pads anchored on the rim
of the device are fairly large. Fig. 11 demonstrates capacitance
Capacitance changes from the micro-accelerometer are read
out by a
switched-capacitor circuit, which can operate either in open- or closed-loop. The circuit includes chopper stanoise,
bilization and correlated double sampling to cancel
amplifier offset, and compensate for finite amplifier gain. It operates using a 1 MHz clock and can resolve better than 10 aF
with dynamic range of 120 dB for 1 Hz BW, while dissipating
less than 12 mW from 5 V supply [21]. Fig. 12 shows the CMOS
capacitive interface chip and its hybrid connection to the accelerometer. Two fixed external reference capacitors are used to
establish a full-bridge scheme. With 0.2 V/pF gain of the interface circuit, the sensor module is expected to provide an overall
system gain of 1.1 V/g. However, the measured system gain is
0.49 V/g. We do not know the source of this discrepancy.
The output noise of the hybrid module is measured with a HP
3561 dynamic signal analyzer with a 50 k reference resistor
shown in Fig. 13. This figure indicates that the resistor has 34
nV/ Hz noise density which matches well with its estimated
thermal noise (note that the measurement bandwidth (BW) is
11.72 Hz in these measurements). Thus, the hybrid module can
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JOURNAL OF MICROELECTROMECHANICAL SYSTEMS, VOL. 13, NO. 4, AUGUST 2004
TABLE IV
GAIN/NOISE COMPARISON FOR ALL CAPACITIVE ACCELEROMETERS
vides 5.6 pF/g and 1.6 g/ Hz noise floor, resulting in a 3500
Gain/Noise ratio.
V. CONCLUSION
A high-sensitivity, low-noise in-plane silicon accelerometer
is demonstrated. The accelerometer has a full wafer thick
proof-mass, large sense area, and small sensing gap. This
provides very high sensitivity and low mechanical noise floor
(0.7 g/ Hz). This is achieved by fabricating the device with
well-characterized combined surface and bulk micromachining
technology. The fabricated accelerometer has 5.6 pF/g sensitivity with low offset (0.14 pF) and good linearity. High
performance readout circuit was used to measure gain and
noise floor of hybrid accelerometer system. The accelerometer
hybrid-assembled with CMOS interface circuit provides 0.49
V/g of system gain and can resolve 1.6 g in 1 Hz BW.
p
Fig. 13. Output noise of the hybrid module shows 1.6 g/ Hz input referred
noise density.
TABLE III
MEASURED HYBRID MODULE SPECIFICATIONS
ACKNOWLEDGMENT
The authors thank Dr. A. Salian, Mr. B. Casey, Mr. R. Gordenker, Ms. M. Loy, and the staff at WIMS, The University of
Michigan.
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Conference on Micro Electro Mechanical Systems (MEMS’03), Kyoto,
Japan, 2003, pp. 466–469.
Junseok Chae (M’03) received the B.S. degree in
metallurgical engineering from the Korea University,
Seoul, Korea, in 1998 and the M.S. and Ph.D. degrees
in electrical engineering and computer science from
the University of Michigan, Ann Arbor, in 2000 and
2003, respectively.
Since then, he has been a Postdoctoral Research
Fellow. His areas of interests are MEMS sensors, mixed-signal interface electronics, MEMS
packaging, and ultrafast pulse (femtosecond) laser
for micro-/nano- structures. He holds a couple of
patents.
Dr. Chae received the 1st place prize and the best paper award in Design
Automation Conference (DAC) student design contest in 2001 with the paper
entitled “Two-dimensional position detection system with MEMS accelerometer for mouse application”. He had an invited talk at Microsoft, Inc., regarding
“MEMS technology for consumer electronic applications”.
635
Haluk Kulah (M’03) was born in Ankara, Turkey,
in 1975. He received the B.Sc. and M.Sc. degrees in
electrical engineering with high honors from Middle
East Technical University (METU), Ankara, Turkey,
in 1996 and 1998, respectively. He received the Ph.D.
degree in electrical engineering from The University
of Michigan, Ann Arbor, in January 2003.
He received “1999 Thesis of The Year Award”
given by Prof. Mustafa N. PARLAR Education
and Research Foundation in METU with his M.Sc.
thesis. Since then, he has been working as a Research
Fellow at the University of Michigan. His research interests include micromachined inertial sensors, infrared detectors, MEMS-based energy scavenging,
and mixed-signal sensor interface electronics design.
Dr. Kulah was the winner of the several prizes in Design Automation Conference (DAC) 2000 and 2002 Student Design Contests, which is sponsored by a
number of companies including CADENCE, Mentor Graphics, TI, IBM, Intel,
and Compaq.
Khalil Najafi (S’84–M’86–SM’97–F’00) was born
in 1958. He received the B.S., M.S., and the Ph.D.
degrees in 1980, 1981, and 1986 respectively, all in
electrical engineering from the Department of Electrical Engineering and Computer Science, University
of Michigan, Ann Arbor.
From 1986 to 1988, he was employed as a Research Fellow, from 1988 to 1990, as an Assistant Research Scientist, from 1990 to 1993, as an Assistant
Professor, from 1993 to 1998, as an Associate Professor, and since September 1998 as a Professor and
the Director of the Solid-State Electronics Laboratory, Department of Electrical
Engineering and Computer Science, University of Michigan. His research interests include: micromachining technologies, solid-state micromachined sensors, actuators, and MEMS; analog integrated circuits; implantable biomedical
microsystems; hermetic micropackaging; and low-power wireless sensing/actuating systems.
Dr. Najafi was awarded a National Science Foundation Young Investigator
Award from 1992 to 1997, was the recipient of the Beatrice Winner Award for
Editorial Excellence at the 1986 International Solid-State Circuits Conference,
of the Paul Rappaport Award for coauthoring the Best Paper published in the
IEEE TRANSACTIONS ON ELECTRON DEVICES, and of the Best Paper Award at
ISSCC 1999. In 2001, he received the Faculty recognition Award, and in 1994
the University of Michigan’s “Henry Russel Award” for outstanding achievement and scholarship, and was selected as the “Professor of the Year” in 1993.
In 1998 he was named the Arthur F. Thurnau Professor for outstanding contributions to teaching and research, and received the College of Engineering’s
Research Excellence Award. He has been active in the field of solid-state sensors and actuators for more than eighteen years, and has been involved in several
conferences and workshops dealing with solid-state sensors and actuators, including the International Conference on Solid-State Sensors and Actuators, the
Hilton-Head Solid-State Sensors and Actuators Workshop, and the IEEE/ASME
Micro Electromechanical Systems (MEMS) Conference. He is the Editor for
Solid-State Sensors for IEEE TRANSACTIONS ON ELECTRON DEVICES, Associate Editor for IEEE JOURNAL OF SOLID-STATE CIRCUITS, an Associate Editor
for the Journal of Micromechanics and Microengineering, Institute of Physics
Publishing, and an editor for the Journal of Sensors and Materials.
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