Sensors are becoming ubiquitous in our lives and possible applications are countless. Micro and nanotechnologies are the natural choice for enabling complex sensor nodes, as they are small (thus unobtrusive), cheap and low power. Carbon nanotubes (CNTs) are a perfect example of how nanosystems offer features unachievable with microsystems: their outstanding structural, mechanical and electronic properties have immediately resulted in numerous device demonstrators from transistors, to physical and chemical sensors, and actuators. A key idea of the project is to combine elements from the fundamental knowledge base on the physics of carbon nanotubes, gathered in the past several years, and the fundamental engineering sciences in the area of micro/nano-electromechanical systems, to develop novel devices and processes based on CNTs.
Specificaly, it seeks to demonstrate concepts and devices for ultra-low power, highly miniaturized functional blocks for sensing and electronics. Due to their small mass and high stiffness, doubly clamped CNTs can exhibit huge resonant frequencies. These are carbon nanotube resonators which, as recently demonstrated or predicted theoretically, can reach the multi-GHz range, can be tuned via straining over a wide range of frequency, offer an unprecedented sensitivity to strain or mass loading, exhibit high quality factors, and all these with a very low power consumption.
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Cabtures
1. Nano‐Tera.ch ‐ Annual Plenary Meeting, Bern, May 12, 2011
Enabling Autonomous Sensor Nodes:
Tunable Carbon Nanotube Electro-
Mechanical Resonators (CabTuRes)
C. Hierold, C. Roman
W. Andreoni, A. Magrez / L. Forró , O. Gröning, A. Ionescu,
M. Kayal, B. Nelson, D. Poulikakos, D. Briand / N. de Rooij
12.05.2011
2. Overview
5 mm
CabTuRes proposes a SiP solution to integrate CNT resonators (NEMS) with readout
electronics (CMOS IC) within a package adapted to application (cap wafer)
CabTuRes is an interdisciplinary engineering research project at the cross roads between
basic science and engineering with great innovation potential and high commercial
opportunities for Swiss industry.
19.05.2011
3. Main deliverables in
I. Tunable CNT resonators as a platform, enabling low-power
sensors and devices for autonomous complex sensor systems
for health, security and the environment
II. A System-in-Package (SiP) technology platform, integrating
CMOS, MEMS and CNTs (or other nanostructures) for many
future applications
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4. Potential applications
Tunable CNT resonators enable a wide range of apps such as:
a. Sensors:
CabTuRes demonstrator
b. Electronics:
CabTuRes demonstrator
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5. Rationale: mass balance
Miniaturization per se is not the
motivation but all the benefits
coming with miniaturization….
Yes, it is miniature and it is ultra low-power
What else?
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6. Mass detection: CNTs vs. SiC
Yang et al, Nano Lett. 6, 583 (2006)
Yang et al, Nano Lett. 11, 1753 (2011) Lassagne et al, Nano Lett. 8, 3735 (2008)
20 zg @ 300 K
7 zg @ 4.2 K
1.4 zg @ 5 K
128 MHz
900 nm × 2 nm
190.5 MHz SWNT
2.3 μm × 150 nm × 100 nm
SiC
First CNT mass sensors (2008) have
surpassed in mass resolution state of
the art SiC
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7. Mass detection: Record holders
CNT resonators have achieved atomic resolution:
[Jensen08] 0.13 zg (0.4 Au atom) @ 10-10 torr (shown) using singly
clamped CNT field emission device
[Chiu08] 0.085 zg (1 Ar atom)
Jensen et al, Nature Nano. 3, 533 (2008)
@ 6 K (not-shown) using SET
detection
[Hüttel09] extrapolate (not
measured) resolution to 7 yg
(1 He atom) @ 20 mK using
ultraclean SWNTs with Q~105
(@350 MHz)
Chiu et al, Nano Lett. 8, 4342 (2008)
Hüttel et al, Nano Lett. 9, 2547 (2009)
19.05.2011
8. Rationale: mass balance
Miniaturization per se is not the
motivation but all the benefits
coming with miniaturization….
Yes, it is miniature and it requires ultra low-power to excite/readout a
nanoresonator
Unprecedented mass resolution in comparison to nanowires and QCMs
(~1 cm size) in UHV and low temperature demonstrated in literature
SNR and Q for SWNT resonators at ambient conditions must be investigated
Unprecedented mechanical tuning range of SWNTs (yield strain up to 5%)
allows for a very large measurement range in closed loop operation.
High sensitivity for mass balance because of low m and high ω0
Goal: ultra low power and small size & weight is conditional for
autonomous sensor systems
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9. The CABTURES Team
T6: System T3: MEMS T2: SWNT fund.
in Package with CNTs properties
T4: CNT mech.
interfaces
T1: CNT growth
& integration
T5: CMOS IC
& sys. model
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10. T6: System level assembly and encapsulation
Defined a consistent 3D System-in-Package
integration process, incorporating the CNT
NEMS fabrication process, hermetically
packaging the NEMS chip and electrically
connecting the NEMS and CMOS chips (by TSVs)
Rokhaya Gueye Teru Akiyama
Danick Briand Shih-Wei Lee
19.05.2011
11. T6: System level assembly and encapsulation
Achieved hermetic packaging via Au-Si
eutectic bonding of a glass cap wafer with
predefined cavities onto a Silicon wafer
Rokhaya Gueye Teru Akiyama
glass cap wafer with deep cavities of 300 µm
bonded to a Si wafer
Danick Briand Shih-Wei Lee
19.05.2011
12. T6: System level assembly and encapsulation
Demonstrated a Through-Silicon Via (TSV)
process flow withstanding both CNT growth
temperature and device HF release
Rokhaya Gueye Teru Akiyama
KOH -TSVs (backside view)
Danick Briand Shih-Wei Lee
19.05.2011
13. T3: Resonator design, fabrication and characterization
Developed a CNT resonator fabrication
process based on SoI with contaminant-
free, in situ grown SWNTs contacted by
thick post-metallization and consistent
with the integration SiP process
Shih-Wei Lee Matthias Muoth
tilted SEM view of a suspended CNFET
Hengky Chandrahalim Cosmin Roman
19.05.2011
14. T3: Resonator design, fabrication and characterization
Demonstrated a contact passivation
process based on ALD Al2O3 to prevent
long term degradation of the contact
resistance
Shih-Wei Lee Matthias Muoth
Hengky Chandrahalim Cosmin Roman
19.05.2011
15. T3: Resonator design, fabrication and characterization
Developed a characterization setup to
excite the CNT resonator and readout its
motion via the DC component of the
piezoresistance
Shih-Wei Lee Matthias Muoth
Hengky Chandrahalim Cosmin Roman
19.05.2011
16. T3: Resonator design, fabrication and characterization
Demonstrated
Shih-Wei Lee Matthias Muoth
operating tensile
MEMS actuators post-
growth by performing
tensile tests in SEM
Hengky Chandrahalim Cosmin Roman
19.05.2011
17. T1: Carbon nanotube integration
Developed a process to define catalyst
particles (LANS) at precise locations (within
80 nm2) from which clean, long CNTs with
high yield (100%) and narrow diameter
distribution (1.2±0.25 nm) were synthesized
Massimo Spina Arnaud Magrez
1μm
Shih-Wei Lee Matthias Muoth
19.05.2011
18. T4: Mechanochemical clamping at contacts
Developed a process to fabricate suspended
CNT samples compatible with nano-
manipulation inside both SEM and TEM to
test the mechanical clamping strength
Simone Schürle Manish Tiwari Kaiyu Shou
Shih-Wei Lee Matthias Muoth
w.o. metal clamping: failure on contact w metal clamping: failure at CNT outside contact
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19. T4: Mechanochemical clamping at contacts
Developed a lateral force microscopy (LFM)
technique including a diamagnetic levitation
calibration procedure to enable accurate
stiffness acquisition of individual-SWNTs
2 m
Simone Schürle Manish Tiwari Kaiyu Shou
Shih-Wei Lee Matthias Muoth
19.05.2011
20. T2: Defect analysis and functionalization
Developed tools to analyze the impact of
chemical functionalization on SWNTs based
on Scanning Tunneling Spectroscopy (STS),
showing that hydrogenation is reversible and
just weakly perturbing electronic properties
(no QD states formed)
O. Gröning Rached Jaafar
W. Andreoni Fabio Pietrucci Jaap Kroes
19.05.2011
21. T2: Defect analysis and functionalization
Analyzed via Density Functional Theory (DFT)
calculations binding energies of different
hydrogen adsorption configurations including
their impact on the electronic properties, and
by Classical MD the impact of topological
defect concentration on Young’s modulus
O. Gröning Rached Jaafar
W. Andreoni Fabio Pietrucci Jaap Kroes
19.05.2011
22. T5: Integrated electronics and system properties
Designed a wideband readout circuit (1-
103MHz) for the CNFET
Defined an oscillator feedback loop around the
CNT resonator based on the AC piezoresistance
component
Ji Cao Dimitrios Tsamados
Christian Kauth Marc Pastre
19.05.2011
23. T5: Integrated electronics and system properties
Developed a fabrication process flow for
prototyping double gate, vibrating body
CNFETs, to extract their small-signal model
parameters and measure AC piezoresistivity
200 nm
Ji Cao Dimitrios Tsamados
1 m
By J. Cao @ EPFL
Christian Kauth Marc Pastre
19.05.2011
24. Summary and Conclusions
CabTuRes is a technology integration project between nine partner
groups: integration of functional nano structures with CMOS circuits
and zero level packaging
The process flow for integration is settled, minor changes possible
The unit processes for SWNT growth are under development and
follow the constraints of the integrated process flow: suspended
SWNT FETs achieved
The oscillator circuit architecture is preliminary defined, utilizing the
2*f0 piezoresistive current modulation of a resonating suspended
SWNT FET. Modeling and parameter extraction has started.
Tasks for basic investigations: SWNT localization and radius control,
mechanical clamping and damping, defect density and impact on
electronic properties, are contributing significantly to the knowledge
about SWNT mechanical and electronic properties
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25. Additional information and technical details
For more information please consult any of the 6 CabTuRes posters
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26. The CabTuRes team thanks you!
Group picture on 14.10.2009 at ETH Zurich
19.05.2011
