18-200
Introduction to Nanotechnology
& Nanoelectronics
Yi Luo
ECE 18-200
Nov 10, 2005
11/10/05
1
Some facts:
Nanoscience and nanotechnology are “hot”. It is one of the most-talked about
topics among scientific and engineering communities. Government agencies and
industry are investing ~ $2 billion per year directly on nanotechnology.
What is “Nanotechnology” ?
Nanotechnology is the understanding and control of matter at dimensions of roughly
1 to 100 nanometers, where unique phenomena enable novel applications.
Encompassing nanoscale science, engineering and technology, nanotechnology
involves imaging, measuring, modeling, fabricating, synthesizing and manipulating
matter at this length scale.
Which area is it involved ?
Many scientific disciplines, e.g. physics, chemistry, biology, medicine, and
materials etc., and almost all engineering fields. It expands over many industrial
areas such as electronic, health care, chemical, so on and so forth.
Can you name any nanotechnology or anything made with
nanotechnology ?
11/10/05
2
Transistor
(2005)
Switching
molecule
O
O
MeS S
N S S N
S S
N
N
N
O
O
4 nm
O
O
S
H2O
~0.2nm
O
O
O
O
O
O
O O
OMeO MeO
MeO
.
.
.
11/10/05
nucleus of hydrogen (proton)
~ 0.000001 nm
1 fm = 10-15 m
Source: National Nanotechnology Initiative
3
Is “nano” special in nature?
Probably not.
… kilo-, meter, milli-, micro-, nano-, pico-, femto-, atto-…
Why nanotechnology is getting popular now?
1. now we are able to image, make, and manipulate
materials on this scale;
2. there are needs and applications in the real world
(justified by the costs).
11/10/05
4
Two major distinct approaches build to nanoscale systems :
1. the more traditional approach:
“top-down” – starting from bulk materials to fabricate nanostructures
via patterning, etching, and deposition, etc.; more physical flavored.
Best represented by CMOS technology.
2. the novel approach:
“bottom up” – starting from basic elements to synthesize and
assemble more complicated nanostructures; more chemical flavored.
Nanocrystal, carbon nanotube, supramolecule, etc.
For the rest of the lecture, we are discuss nanotechnology based on
these two approaches.
11/10/05
5
Top-down Approach
(best represented by CMOS fabrication)
11/10/05
6
A close look of FET
(field effect transistor)
Source: Intel
The challenge is to make a billion of them on a chip.
11/10/05
7
There are over 200 processing steps in
CMOS IC fabrications.
To name a few:
patterning
etching
metalization
implantation
deposition
cleaning
CMP
annealing
wafer bonding
packaging
.
.
.
Source: intel
This time we will only talk about how to make small things.
11/10/05
8
Optical Lithography
-sub micron technology
UV light radiation
Develop with solvent
SUSS MA6
Mask
Photo-resist
Si wafer
Advantage – very mature, fast, parallel processing.
Limits – relatively large feature sizes, mask can be
very expansive.
SUSS MA200/300PLUS
11/10/05
9
EUV Lithography
EUV system at ALS in LBL
-Deep sub-micron technology
-10’s to ~100 eV incident light
How it works:
The scanning mirror directs focused EUV light from the Kirkpatrick-Baez mirrors into the
converted interferometer with the desired degree of spatial coherence and illumination pattern.
Installed inside the interferometer tank, the Set-2 optic images the EUV light reflected from the
mask-carrying reticle onto a resist-covered silicon wafer.
Advantage –small patterns, can be reasonably fast;
Limits – can be very expensive.
11/10/05
10
Electron Beam Lithography
High energy electrons (30-200 KeV) have
much shorter wavelength (~ pm). Beam size
can be sub-nanometer.
Primary beam
e-
Quanta 600 FEG (FEI Company)
secondary electrons
beam exposure
eebeam resist
Substrate
post-development
ebeam resist
Substrate
11/10/05
JBX-9300FS Electron
Beam Lithography System
11
Electron Beam Lithography
4 nm
K. Yamazaki and H. Namatsu, Jpn J.
Appl Phys,Vol 43, 6B, 3767 (2004).
Muray, Isaacson, and Adesida, Appl.
Phys. Lett., Vol 45, 589 (1984).
10-15 nm
Wavelength is not an issue. Beam size can
be sub-nanometer.
Done here at CMU !
Advantage – small arbitrary patterns, no mask is needed.
Limits – serial process, slow.
11/10/05
12
Nano-Imprint Lithography
SB6e - Suss
A schematics introduction
1
2
Master/Mold
Master/Mold
polymer
Si
Si
hυ
or/and
4
heat
3
Master/Mold
Master/Mold
Si
11/10/05
NPS 300 -Suss
Si
13
Cross-bar Memory – 1011bit/cm2
Pt
1 Kbit
Si
Ordered Nanowires
array with extremely
high density
Heath Group – Caltech
Imprint mold with
10nm diameter pillars
11/10/05
J M DeSimone Group – UNC/NCSU
Holes imprinted
in PMMA
Metal dots
fabricated by NIL
S.Y. Chou Group - Princeton
14
Techniques to make nanoscale patterns from
top-down – lithography with:
UV light,
ebeam,
EUV,
X-ray,
Imprint,
etc.
It is likely that the scaling of CMOS will continue down
to 22nm node (~10nm channel length).
11/10/05
15
11/10/05
16
Bottom-up Approach
• SPM – imaging, and building structures atom by atom;
• Synthesis and applications of nanocrytal, nanotube,
nanowire, and supramolecule;
• Self-Assembling of nano-components;
• Nanoelectronics with molecules.
11/10/05
17
SPM – Microscopes that can “see” and move atoms
Tunneling Current
STM
Fe atom
position
A
AFM
Quantum Corral
Source: IBM
Laser beam
deflection
Laser
11/10/05
position
Ge/Si(105) surface
(NCAFM image )
Si(111) 7x7 reconstruction surface
Source: Omicron
18
Atoms and molecules can be
precisely manipulated by STM tips
Low-temperature STM image of -CH3
on Si(111) surface. (Heath, Caltech)
C60 , ~ 1nm
“nano-abacus” formed by C60 molecule along
single atomic steps on copper surface.
(Jim Gimzewski, UCLA)
11/10/05
Development of One-Dimensional Band Structure
in Artificial Gold Chains, W. Ho Group, UC Irvine.
19
Nanocrystal / Nanoparticle
Brus, Columbia
Bawendi Group,
MIT
Optoelectronic
11/10/05
applications
Quantum confinement
- size effect 20
Fullerenes
A whole family of Bucky Balls
C28, … C60, C70,… C240…
C60
Carbon NanoTubes
11/10/05
http://www.photon.t.u-tokyo.ac.jp/~maruyama/agallery/agallery.html
21
Carbon Nanotubes
Carbon Nanotubes H. Dai Group, Stanford Univ.
Carbon Nanotube sensor and transistor
C. Dekker Group, Delft Univ of Tech
11/10/05
22
Semiconductor Nanomaterials
Semiconductor Tetrapod
Alivisatos Group, Berkeley
Chemical and biochemical sensing
11/10/05
Semiconductor
Nanowires, Lieber Group, Harvard
Peidong Yang Group, Berkeley
23
Self-Assembled Molecular Monolayer
Atomic Force Microscope
Image of SAM on Au
S S S S S S S S S
Au
11/10/05
24
DNA Nanotechnology
Specifically designed DNA building blocks
11/10/05
Seeman, NYU
25
DNA-Based Computation and Algorithmic Assembly
-a cool example: Yi = XOR [Yi-1,Xi]
11/10/05
Seeman - NYU & Eric Winfree - Caltech
26
Supramolecules – advanced multifunctional molecules
Molecular Borromean Rings
Molecular Muscles
J. Fraser Stoddart Group, UCLA
11/10/05
M. FUJITA Group
University of Tokyo
27
Bi-stable molecules
O
O
O
O
N
O
O
N
N
S
S
S
S
N
O
O
O
O
O
O
O
O
C14+
N
S
S
N
O
O
S
O
S
MeS
N
N
S
S
S
S
N
N
N
V=0 volt
V=-1 volt
V=+1 volt
N
N
O
O
O
O
O
O
N
O
N
S
S
O
O
S
N
O
O
S
S
O
O
O
O
O
S
N
O
O
C24+
R14+
O
O
OH
R24+
O
O
O
O
OMeO MeO
MeO
O
Figure 1
solution
Absorbance
O
polymer
400
500
600
700
λ / nm
800
900
Fraser Stoddart’s Group
11/10/05
CNSI / UCLA
28
Cross-bar Memory – 1011bit/cm2
MS
Schematics
MS
MS
MS
1 Kbit
Device Structure
molecule
p-type
Science, December 21, 2001
n-type
Current (nA)
1.0
All bits OFF
0.8
0.6
0.4
0.2
0.0
0
Si
100
200
Bits
400
500
600
500
600
1.0
Selective bits ON
Current (nA)
0.8
Metal
300
0.6
0.4
0.2
0.0
0
100
200
300
400
Bits
11/10/05
Heath Group – Caltech
29
single-molecule transistor
10
7nm Ag nano-particle
5
Molecular states
VS-D
VG (volt)
Schematic energy diagram
0
Ef
-5
source
drain
-10
-0.2
-0.1
0.0
VS-D (volt)
0.1
0.2
0.10
VG
0.05
gate
VG(V)
0.0
Molecular energy levels
can be tuned by gate potential.
-0.05
-0.10
Break-junction with single molecule (gap
size can be controlled between ~1 to 10 nm).
5nm long molecule
-0.15
-20
-10
0
10
VSD(mV)
30 nm silicon oxide
Au or Pt electrode
11/10/05
Gate electrode
(degenerately doped poly-Si)
30
20
Single Molecule Transistor
Fabry-Perot measurement
for electron wave
P.L. McEuen Group, Cornell Univ.
HK Park, Harvard Univ.
11/10/05
31
A True Single Molecule Transistor
Opportunities to go much smaller than 10 nm
where top-down and bottom-up meet !
Pt
S
H
N
H
N
N
H
H
N
H
N
N
N
H
n
<10 nm
Pt
S
n
source
LUMO
drain
H N
HOMO
source
drain
N H
H N
Tunneling
barrier
PO 4
TiO2/Ti
gate
gate
Tunneling
barrier
LUMO-lowest Unoccupied Molecular Orbital
HOMO-highest Occupied Molecular Orbital
• Built-in gate to increase gating efficiency
• Tunneling barriers to adjust coupling
• Anchoring groups to realize Selective-Self- Attachment
Conductive and Semiconductive
Oligomers
• bandgap ~ 1-3 eV
• chemically or electrically doped
• polymer conductivity ~ 5x102 (S cm-1)
11/10/05
acetylene
phenylene
S
S
S
S
thiophene
32
Just in the world of electronics
In six decades, device features have
been reduced by x 106!
1947, Shockley,
Bardeen, &
Brattain
1958, Kilby
1971, Intel 4004
Number of transistors on a chip
approaching 1 billion vs. 100 billions to
1 trillion neural networks in an average
human brain.
11/10/05
current, Intel Xeon
(65nm generation,
36nm channel length)
(Source: Intel)
Entering the world
where molecules and
chemistry work the
best!
What’s next?
(< 10nm)
How to get there?
33