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Monolithic Integrated Antennas and Nanoantennas
for Wireless Sensors and for
Wireless Intrachip and Interchip Communication
Peter Russer1, Nikolaus Fichtner1, Paolo Lugli1,
Wolfgang Porod2 and Hristomir Yordanov1
1Institute for Nanoelectronics, Technische Universität München, Germany
2Center for Nano Science and Technology, University of Notre Dame, USA
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Contents
1.
2.
3.
4.
Introduction
CMOS Integrated Antennas
Nanoantennas with MOM Tunnel Diodes
Nanoantennas Based on Carbon Nanotubes and
Graphene
5. Alternative Materials and Fabrication Techniques
6. Outlook
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On-Chip Nanoantennas for
Sensing and Communication
• As the structure size of circuit devices and components is
continuously decreasing the same will hold for antennas
and radiation elements used in integrated circuits for onchip and chip-to-chip communication.
• Following the general scaling trend on-chip antennas will
soon enter the micrometer- and even the nanometer
regime.
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Introduction
• The rate of signal transmission on or between monolithic integrated
circuits is limited by the cross-talk and the dispersion due to the wired
interconnects.
• An interesting option to overcome the bandwidth limitations is wireless
chip-to-chip and on-chip interconnects via integrated antennas.
• The electromagnetic coupling of antennas may occur via waves
radiated into space and scattered by objects or via surface waves.
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Inter-Chip and Intra-Chip
MIMO Communication
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The Wireless MIMO Channel Model
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Contents
1.
2.
3.
4.
Introduction
CMOS Integrated Antennas
Nanoantennas with MOM Tunnel Diodes
Nanoantennas Based on Carbon Nanotubes and
Graphene
5. Alternative Materials and Fabrication Techniques
6. Outlook
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On-chip meander antenna
An intrachip wireless interconnect system using meander monopole on-chip
antennas and operating at 22 GHz to 29 GHz is described in
M. Sun, et al., “Performance of Intra-Chip wireless interconnect using On-Chip antennas and
UWB radios,’’ IEEE Trans. on Ant. & Prop., vol. 57, no. 9, pp. 2756-2762, 2009.
On-chip UWB radios in that frequency band are discussed there. The on-chip
antennas arevmeander monopoles with 1 mm axial length.
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CMOS Integrated Antennas
Schematic drawing of a chip with an integrated antenna
• Instead of dedicating chip area for the antenna the antenna can
make use of the available on-chip metallization.
• This can be obtained by dividing the top metallization layer into
patches and impressing an RF signal across the gap between the
patches.
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Differential Lines, Connecting the Digital Circuits
Under the Separate Antenna Patches
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Chip with Integrated Antenna
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1.1 mm
CMOS Integrated Antennas
2 mm
50 mm
Simulated current distribution of a two-patch antenna operated at 66 GHz
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CMOS Integrated Antennas
Photograph of the open slot antenna
H. Yordanov and P. Russer, “Area-efficient integrated antennas for inter-chip communication,”
Proc. of the 40th European Microwave Conference, EuMC 2010, Paris, France, Sep 2010.
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Antenna Characteristics
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Antenna Impedance vs. Gap Width
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CMOS Integrated Antennas
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CMOS Integrated Antennas
Main Direction
Minimum Direction
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Contents
1.
2.
3.
4.
Introduction
CMOS Integrated Antennas
Nanoantennas with MOM Tunnel Diodes
Nanoantennas Based on Carbon Nanotubes and
Graphene
5. Alternative Materials and Fabrication Techniques
6. Outlook
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Integration of Antennas with MOM Diodes
• A promising novel concept for infrared (IR) detectors is the
combination of a nanoantenna with a rectifying element.
• The rectifying element extracts a DC component from the
rapidly-varying current delivered from the nanoantenna.
Semiconductor diodes are widely used, but they encounter
frequency limitations for the mm-wave and long-wave IR
regime.
• It has been demonstrated that MOM tunnel diodes can
provide rectification for IR and even optical radiation
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Antenna with Integrated MOM Diode
The MOM dieode is naturaly formed at the overlaparea
between the antenna arms
P. Esfandiari, G. Bernstein, P. Fay, W. Porod et al., “Tunable antennacoupled
metal-oxide-metal (MOM) uncooled IR detector,” in Proc. of
SPIE, vol. 5783, 2005, pp. 471 – 482.
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ACMOMD Design
Design 1
Shadow evaporation
antenna
diode formed
antenna
Al
Design 2
Pt
MOM diode
Al-AlOx-Pt
Two step lithography
Al
Pt
MOM diode
Al-AlOx-Pt
Electrical leads
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Symmetric MOM - Unbiased
linearly
polarized IR
radiation
Metal X
Oxide Metal
X
Electrode 1
QM
Tunneling
Al-AlOx-Al
nanoantenna
Metal Oxide Metal
Net e-transfer for
one half cycle
Electrode 1 Electrode 2
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Metal Oxide Metal
Net e-transfer for
other half cycle
Electrode 1  Electrode 2
Electrode 2
For symmetrical barrier
MOM
No net e-transfer over
complete cycle of IR
radiation
No net QM Tunneling
current
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Symmetric MOM - Biased
Symmetric MOM - Biased
linearly
polarized IR
radiation
Al-AlOx-Al
nanoantenna
Metal X
Electrode 1
Metal X
Electrode 2
+applied
biased
Biased symmetric MOM
diode
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Electrode 1
Electrode 2
Electrode 1
Electrode 2
For BIASED symmetrical barrier MOM
Net e-transfer over complete cycle of IR radiation
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Asymmetric MOM
Asymmetric MOM - Unbiased
linearly polarized IR
radiation
Δ
1
2
Vacuum level
Metal X
Electrode 1
W2
W1
Al-AlOx-Pt
nanoantenna
Metal
Metal X
Electrode 1
X
Metal Y
Electrode 2
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Oxide
Metal Y
Electrode 2
Equilibrium condition
Δ = 1 2=W1-W2
Metal
Y
Metal X
Electrode 1
Metal Y
Electrode 2
For unbiased asymmetrical barrier
MOM
Net e-transfer over complete cycle
of IR radiation
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Two Step Lithography Devices
Optical Microscope Images
20 finished devices through 2 step lithography process
Corresponding SEM image
2-step lithography dipole antenna
Al-AlOx-Pt
Overlap
50x80 nm
Al
Pt
Gold
bonding
pads
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SEM Image of a Shadow Evaporation Device
J. A. Bean, B. Tiwari, G. H. Bernstein, P. Fay, and W. Porod, “Thermal infrared detection
using dipole antenna-coupled metal-oxide-metal diodes,” Journal of Vacuum Science &
Technology B: Microelectronics and Nanometer Structures, vol. 27, p. 11, 2009.
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One Step Lithography Devices
MOM overlap area of a Shadow evaporation device
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Polarization Dependent Response
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Contents
1.
2.
3.
4.
Introduction
CMOS Integrated Antennas
Nanoantennas with MOM Tunnel Diodes
Nanoantennas Based on Carbon Nanotubes and
Graphene
5. Alternative Materials and Fabrication Techniques
6. Outlook
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Carbon Nanotube Antennas
• A further considerable size reduction of integrated antenna
structures may be achieved using CNTs.
• CNTs exhibit exceptional electron transport properties,
yielding ballistic carrier transport at room temperature with a
mean free path of around 0.7 mm and a carrier mobility of
10,000 cm2/Vs.
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Carbon Nanotube Antennas
• Quantum transport effects in the CNT yield a quantum
capacitance CQ and a kinetic inductance LK in addition to
the geometric capacitance CG and inductance LG.
• The phase velocity for the modified equivalent circuit is
around 0.02 c0 which is in accordance with the reduced
wavelength of the surface plasmons.
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Carbon Nanotube Antennas
• Due to the extremely high aspect ratio (length to cross sectional
area), CNTs have AC resistances per unit length in the order of
several kW/μm.
• This causes high conduction losses and thus seriously
decreases the efficiency and the achievable gain
ofnanoantennas.
• This problem could be bypassed using of arrays of
nanoantennas or a bundle of parallel nanowires.
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Graphene Antennas
• Like CNTs, graphene also exhibits excellent conductivity and slow
wave properties. The achievable slow-wave effect in plasmon modes is
in the order of c0/100.
• At THz frequencies a population inversion in the graphene layer can be
realized by optical pumping or forward bias which yields an
amplification of the surface plasmon.
• Graphene allows the realization of planar structures and also the
realization of active circuits.
J. Moon et al., “Development toward Wafer-Scale graphene RF electronics,” in Topical Meeting
on Silicon Monolithic Integrated Circuits in RF Systems, January 11–13, 2010, New Orleans, LA,
Jan 2010, pp. 1-3.
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Graphene Antennas
Theoretical investigations have shown that antennas with sizes in the
order of several hundred nanometers are suitable to radiate
electromagnetic waves in the terahertz band, i. e. from 0.1 THz to 1
THz.
J. M. Jornet and I. F. Akyildiz, “Graphene-based nano-antennas for
electromagnetic nanocommunications in the terahertz band,” in Proc. of
4th European Conference on Antennas and Propagation, EUCAP, 2010.
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Contents
1.
2.
3.
4.
Introduction
CMOS Integrated Antennas
Nanoantennas with MOM Tunnel Diodes
Nanoantennas Based on Carbon Nanotubes and
Graphene
5. Alternative Materials and Fabrication Techniques
6. Outlook
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Alternative Materials and Fabrication Techniques
• The antennas described previously are generally
fabricated with conventional technologies, namely
evaporation of the metallic films followed by patterning via
photo or electron-lithography.
• In the CNT or graphene case, the conductive layers have
to be grown epitaxially on the given substrate.
• Especially when small dimensions are required, as for the
nanometer gaps required in plasmonic structures or in
nanometer scale MOM diodes, a very interesting
alternative could be offered by nanotransfer techniques.
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Schematic of Direct Metal-Transfer
A metal coated high resolution
heterostructure is pressed onto a
substrate, thereby creating
nanometer separated electrodes.
S. Harrer, S. Strobel, G. Scarpa, G. Abstreiter, M.
Tornow, and P. Lugli, “Room temperature
nanoimprint lithography using molds fabricated by
molecular beam epitaxy,” IEEE Trans.
Nanotechnology, vol. 7, no. 3, pp. 363–370, 2008.
S. Harrer, S. Strobel, G. Penso Blanco, G.
Scarpa, G. Abstreiter, M. Tornow, and P.
Lugli, “Technology assessment of a novel
highyield lithographic technique for sub-15nm direct nanotransfer printing of nanogap
electrodes,” IEEE Trans. Nanotechnology,
vol. 8, no. 6, pp. 662 –670, 2009.
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Transfer Metal Pads with a Gap of a Few Nanometers.
• Transferred metal pads, exhibiting
a gap featuring line separations
down to approximately 9 nm.
• The structures could be transferred
along the complete length of the
mold (approximately 4 mm) with an
efficiency of about 80%.
• Structures containing several lines
separated by nanometer gaps
have also been realized.
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Contents
1.
2.
3.
4.
Introduction
CMOS Integrated Antennas
Nanoantennas with MOM Tunnel Diodes
Nanoantennas Based on Carbon Nanotubes and
Graphene
5. Alternative Materials and Fabrication Techniques
6. Outlook
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Universität
München
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Conclusion and Outlook
• As the structure size of circuit devices and components is
continuously decreasing the same will hold for antennas
and radiation elements used in integrated circuits for onchip and chip-to-chip communication.
• Following the general scaling trend,on-chip antennas will
soon enter the m- and even the nanometer regime.
• Integrated antennas based on nanoelectronics provide a
tremendous potential for the realization of novel devices
and systems from DC up to the optical range.
• The applications will cover wireless intra-chip and interchip
transmission at Gbit/s rates, field sensors and photon
harvesting systems.
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Conclusion and Outlook
• Intrachip and interchip wireless broadband communication
at millimeterwave carrier frequencies can be realized in
CMOS technology and will allow the transfer of Gbit/s data
rates.
• A further size reduction of antenna structures will be
possible by integration of CNT and graphene antenna
structures.
• When small dimensions are required, as for the nanometer
gaps required in plasmonic structures or in nanometer
scale MOM diodes, a very interesting alternative could be
offered by nanotransfer techniques.
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