纳米制造手册（导读版）

现代工业使用的众多器件和系统变得越来越小，有的达到纳米尺寸级别。纳米制造的目标在于构建大量高效低成本的用在组件、器件和系统中的纳米结构。纳米制造是所有纳米技术领域的关键所在，特别是纳米技术在传统的工程和科学领域应用方面。本书覆盖了重要的纳米制造技术，每章都全面介绍了一种纳米制造技术。适合化工、材料、物理等相关专业的人员阅读。

编辑顾问委员
前言
编者
1 纳米结构的定向组装 J M MACLEOD,Università degli studi di
Trieste,Trieste,Italy F ROSEI,Université du
Québec,Varennes,QC,Canada
2 有序纳米颗粒超结构的生物调控组装 W L CHENG,S J TAN,M J CAMPOLONGO,M R HARTMAN,J S
KAHN and D LUO,Cornell University,Ithaca,NY,USA
3 表面的手性分子 C J BADDELEY,University of St.Andrews,St.Andrews,UK G
HELD,University of Reading,Reading,UK
4 纳米结构的电子束光刻 D M TENNANT and A R BLEIER,Cornell
University,Ithaca,NY,USA
5 紫外压印光刻在纳米制造中的现状 J CHOI,P SCHUMAKER and F XU,Molecular
Imprints,Inc., Austin,TX,USA S V SREENIVASAN,Molecular
Imprints,Inc.,Austin,TX,USA,University of Texas at
Austin,Austin,TX,USA
6 皮升印刻 E GILI,M CAIRONI and H SIRRINGHAUS,University of
Cambridge,Cambridge,UK
7 分子印刻板:从超分子化学到纳米制造 R SALVIO,J HUSKENS and D N REINHOUDT,University
of Twente,Enschede,The Netherlands
8 分子机械和马达 A CREDI,Università di Bologna,Bologna,Italy
索引

1 Directed Assembly of Nanostructures
J M MacLeod,Universita` degli studi di Trieste,Trieste,Italy
F Rosei,Universite′ du Que′ bec,Varennes,QC,Canada
a 2010 Elsevier B.V.All rights reserved.
1.1 Introduction
The realization that nanoscale matter often behaves
differently with respect to the same materials in the
bulk form has prompted a wealth of research aimed at
understanding,characterizing,describing,and predicting
‘nano’[1,2].However,while‘nanotechnology’has
been a buzzword for almost two decades,it has delivered
fairly little so far in terms of new technologies,that is,
new products that are commercialized and used by the
general public.
One of the great promises of nanotechnology is
the ability to do more in the same space: to advance
our current technologies through miniaturization,so
that each crop of electronics is smaller,faster,and
more powerful than the one before.This is the manifestation
of Moore’s law [3],the now-famous 1965
empirical prediction by Gordon Moore（who later
went on to co-found Intel）that the number of transistors
accommodated in a chip of given size doubles
roughly every two years.The semiconductor industry
has used this prediction as a roadmap over the last
three decades.As the limits of this down-scaling
approach the dimensions of single molecules and
atoms,the discrepancy between nanoscale and bulk
behavior has become evident.While this is detrimental
in some situations,for example,in scaled-down
versions of larger transistors that can exhibit problematic
behaviors,such as unexpected leakiness,at
nanoscale dimensions [4],it opens the door to opportunities
for custom-designing new circuit
architectures to exploit behaviors unique to the
nanoscale.For example,quantum size effects [5,6],
confinement of excitons [7,8],and high surface-tovolume
ratios [9] can all impart new,unexpected,
and potentially useful behavior to nanoscale systems.
To capitalize on the full potential of nanostructured
materials and their properties,it is necessary to
develop the ability to purpose-build nanoscale systems,
a task which hinges on the precise placement of
appropriate nanoscale building blocks in two and
three dimensions（2D and 3D）.This approach is
generally referred to as‘bottom-up’,implying the
spontaneous formation of a desired architecture.
This approach provides a diametric counterpoint to
the‘top-down’techniques（typically lithographic
techniques,which are very precise but must adhere
to Rayleigh’s equation,and therefore cannot resolve
fine nanoscale features [10]）used in the contemporary
fabrication of semiconductor devices [11],and
provides an intuitive mechanism for building architectures
from countable numbers of atoms or
molecules.
The use of molecules as the basic building blocks
of nanoscale structures capitalizes on a wealth of
knowledge that can be obtained from the study of
biological systems [12-14].Supramolecular chemistry
[15],applied to nanoscale design [16-18],
additionally benefits from the capabilities of synthetic
chemists,since molecules can essentially be
custom-designed for form and functionality salient
to specific systems and devices [19,20].
The aim of this article is to provide an overview of
the tools and techniques available for building nanoscale
architectures from molecular building blocks,
limiting ourselves primarily to a discussion of the
geometry of molecular assemblies at surfaces,that
is,structures confined to 2D.Outside of our focus
will be atomic structures [21-24],clusters [25,26],
and quantum dots [27-29],all of which provide their
own unique set of challenges and rewards.Our focus
will be on the major experimental advances made via
surface physics and chemistry over the past 25 years.
The majority of the investigations that we describe
have been performed with scanning probe microscopies
（SPM）,specifically,scanning tunneling
microscopy（STM）[30-34].The STM is a remarkably
versatile instrument capable of imaging
conducting and semiconducting surfaces [35],probing
their electronic characteristics [36],investigating
the vibrational characteristics of adsorbed molecules
[37,38],interacting with the surface or adsorbates to
produce new geometric and electronic configurations
[39-41],or even to initiate chemical bond formation
[42,43].Many excellent books and reviews are
available,describing various facets and uses of
SPM [44-64].
After briefly discussing the fundamentals of directing
nanoscale assembly of surfaces,as well as the most
salient experimental techniques for probing these
systems,we will provide an overview of significant
experiments grouped by the type of interaction used to
pattern the molecules: strong bonding between the
molecules and the underlying surface,molecular selfassembly
driven by hydrogen bonding,and metal-
organic coordination,using inclusion networks to position
molecules,and,finally,surface-confined
polymerization for producing robust,covalently bonded
structures.An emerging area that we will unfortunately
neglect due to space limitations is the formation of
ordered multicomponent assemblies driven by curved
surfaces.We refer interested readers to the relevant
literature [65-77].
1.2 Fundamentals of Directing
Nanoscale Assembly at Surfaces
There are two competing types of interactions that
control the formation of patterns at surfaces:（1）
molecule-molecule and（2）molecule-substrate [78].
In most cases,bottom-up assemblies depend on the
balance between（1）and（2）; however,depending on
the choice of surface（2）can be either the dominant
interaction or can be almost suppressed,with various
intermediate regimes.For example,graphite surfaces
are essentially inert and therefore their participation
in pattern formation is usually minimal besides providing
regular and planar array of adsorption sites.
On the other hand,reconstructed silicon surfaces are
characterized by a high density of reactive unsaturated
dangling bonds（DBs）that interact strongly
with molecules upon adsorption,often causing the
molecules to fragment as in the case of cyclo-addition
reactions [79].With respect to（1）,most intermolecular
interactions used so far are noncovalent in
nature,that is,they may induce the formation of
long-range ordered patterns,yet,are easily disrupted
because of their weak bonding.This aspect has several
advantages,including the‘self-repair’
mechanisms that are well known in supramolecular
chemistry: defects tend to disappear as the interactions
locally break up the pattern forming a new
ordered one devoid of defects.Notably,hydrogen
bonding and metal-organic coordination are noncovalent
interactions frequently employed to form
ordered patterns in both 2D and 3D.van der Waals
forces alone can usually lead to the formation of local
patterns,yet their lack of directionality is usually a
barrier to producing long-range patterns.
Stronger molecule-molecule interactions can lead
to the formation of covalent bonds.While these are
often desirable to obtain more robust structures with
interesting mechanical and electronic properties,
they are significantly more difficult to direct and
their use for nanostructure formation at solid surfaces
has been explored only in the last decade.Some
elegant examples of covalent architectures,together
with a discussion of their challenges and limitations,
will be provided in Section 1.7.
1.2.1 Noncovalent Interactions between
Molecules
1.2.1.1 Hydrogen bonding
Hydrogen bonds are formed between an electronegative
atom and a hydrogen atom bonded to a second electronegative
atom [80].The strength of the hydrogen bond
depends on the electronegativity of the atoms;
Table 1 classifies hydrogen bonds as very strong（e.g.,
[F…H…F] ）,strong（e.g.,O H…OTC）,or weak
（e.g.,C H…O）depending on the bond energy,
which ranges from 40 to <4 kcal mol 1,respectively.
The directionality of the bond increases with strength.
For crystal engineering,the‘strong’hydrogen bond is
perhaps the most useful type [81,82].For example,in the
systems we describe in this article,hydrogen bonds
between carboxylic groups（O H…OTC）are often
used to drive self-assembly.
1.2.1.2 Metal-organic coordination
The attraction between an organic ligand and a metal
center provides an alternative route to creating
directional associations at surfaces.Metal-organic
coordination provides a stronger association than
the commonly employed modes of hydrogen bonding
（typically in the order of 50-200 kJ mol 1 in 3D
compounds）[84],and can confer various geometrical
motifs due to the flexibility of the coordination
modes available in transitional metals [85].
1.2.2 Molecule-Surface Interactions
The attraction between a molecule and an underlying
surface is typically characterized as either physisorption
or chemisorption,depending on the strength of the
interaction.Physisorption generally refers to van der
Waals interaction,and has a maximum interaction
energy of about 60 kJmol 1 for a small molecule [86].
Chemisorption implies higher interaction energy due
to a significant charge rearrangement in the adsorbed
molecule to facilitate the formation of a covalent or
ionic bond with the surface.This is obviously the
dominant case for molecules on semiconductor
2 Directed Assembly of Nanostructures
surfaces; on metal surfaces chemisorption strength
depends on whether the metal has a d-band（the
absence of which leads to relatively weak chemisorption）,
on the filling of the adsorbate-metal antibonding
d-states,and on the orbital overlap between the adsorbate
and the surface [87,88].In general,for transition
metal substrates,the reactivity of the surface decreases
from left to right across the periodic table,and from
top-to bottom [89].We avoid using the total adsorption
energy to distinguish between physisorption and
chemisorption since complex molecules can interact
with the surface over a large area,leading to a total
physisorption energy that can be comparable to chemisorption
energies for smaller molecules even in the
absence of charge rearrangement.
1.2.2.1 Common surfaces for studies
of molecular assembly
1.Highly oriented pyrolytic graphite.While its constituent
graphene sheets have been the source of
extremely intense investigation recently [90-98],
highly oriented pyrolytic graphite（HOPG）holds
its own place of importance in ambient and solution
studies of molecules on surfaces.One reason for this
is the ease with which a clean,flat surface can be
prepared and used: an HOPG crystal can be cleaved
with adhesive tape,and the exposed clean surface
remains stable in air for hours.These properties are
a direct consequence of the bonding between the
carbon atoms.Each atom is sp2 hybridized and
bonded in-plane to three nearest-neighbors to form
graphene sheets,with the remaining electron contributing
to a delocalized  -bond between the sheets.
The   system at the graphite surface is
advantageous
for studies of aromatic molecules,since  – 
interactions
stabilize the molecules on the surface.Long-chain
alkanes can also adsorb stably,with their molecular
axis oriented parallel to the HOPG surface [99,100].In
this configuration,the periodicity of the alternate
methylene groups along the alkane molecule（2.51A°）
is very nearly commensurate with the spacing of the
hexagons in the graphite surface（2.46A°）,providing
strong molecule-surface interaction [101].The subsequent
formation of an alkane monolayer is stabilized by
van der Waals interactions.
It is important to note that care must be taken in
the interpretation of STM images obtained from
HOPG surfaces,since defects in the graphite（e.g.,
those introduced by the rotation of subsurface graphene,
etc.）[102-105] can be easily misinterpreted as
molecular features [106,107].
2.Cu（110）/Cu（111）.The face-centered cubic（fcc）
structure of copper leads to different atomic geometries
on its low-energy faces: Cu（100）is fourfold
symmetric,Cu（110）is twofold symmetric,comprising
atomic rows,and Cu（111）is threefold symmetric,
comprising close-packed atoms.The（110）and（111）
surfaces（Figure 1）are extensively used as substrates
in molecular assembly experiments.The surfaces
present distinct characteristics to molecular adsorbates:
besides the obvious difference in geometry,
the open structure of（110）is associated with a higher
adsorption reactivity than the closed（111）structure
[108].The two surfaces are accordingly used in different
contexts,with（111）being used to favor
molecule-molecule interactions and（110）being
used to impose a twofold symmetry on the molecular
building blocks（see Section 1.5 for examples）.The
anisotropy of（110）has additional implications for the
diffusion of adsorbates,which is enhanced parallel to
the [11ˉ0] direction [109,110].
3.Au（111）.The inclusion of an extra Au atom
once every 22 atoms along [11ˉ0] leads to a massive,
strain-induced（22p3）reconstruction of Au（111）
[111,112].The unit cell comprises both hexagonal
close-packed（hcp）and fcc sites,with a narrow band
of bridge sites between the two.These bridge sites
form the characteristic herringbone bands evident in
STM images（Figure 2）.The spatial and electronic
[113,114] inhomogeneities introduced by this reconstruction
can lead to a templating effect for
adsorbates introduced to the surface.Both atomic
[115,116] and molecular [117] species have been
demonstrated to preferentially adsorb at the‘elbows’
of the herringbones.
Although the Au（111）-（22-p3）surface can be
prepared on a single-crystal metal sample using the
usual ultrahigh vacuum（UHV）techniques [118],it
can also be prepared on thin films of gold deposited
on mica [119-121].The films can be easily prepared
by vacuum deposition of gold onto mica,with subsequent
flame-annealing to improve the quality of
the substrate,or can be purchased commercially.
Gold on mica substrates is amenable to study in
ambient,or in solution.
4.Si（001）.The electronic properties of Group IV
semiconductors have made them the cornerstone of
modern devices [122].Growing useful nanostructures
on a semiconductor surface is therefore of
considerable interest,since this approach offers the
opportunity to integrate novel technologies with
established ones.We focus here the Si（100）surface,
which is nearly ubiquitous in the microelectronics
market [123].
The Si（001）surface has been described in many
insightful reviews [124-126,123],so we will provide
only a brief sketch of the surface structure.The
1.3 nm 1.3 nm [001] [110] – [101] [1-10] –
Figure 1 STM images of Cu（110）（left）and（111）（right）.Unit cells are
outlined in white,and surface directions are specified.
STM image parameters: Vb. 0.4 V,It.1.5 nA（left）,Vb. 0.2 V,It.0.8
nA（right）.Courtesy of J.A.Lipton-Duffin.
Figure 2 STM image of the Au（111）-（22-p3）
herringbone reconstruction.Obtained from http://
ipn2.epfl.ch/LSEN/jvb/collection/coll_au111.htm.
4 Directed Assembly of Nanostructures
Si（001）surface reconstruction is c（4-2）at low temperature,
and（2-1）at room temperature [127,128].
This surface periodicity results from formation of
asymmetric silicon dimers [129],with the 2- periodicity
aligned along [1ˉ10]（traditionally,a surface
that is 2- along the equivalent [110] is referred to as
（1-2）.）The dimerization results in a reduction of
the number of surface DBs from one per atom to one
per dimer.These remaining DBs mean that even the
dimerized surface is quite reactive; exposure to
hydrogen passivates the surface through the formation
of one of several hydrogen terminations,
depending on conditions of preparation [130].
Reactive DB sites can persist as defects after passivation
[131],or can be introduced in a controlled
manner by desorbing a hydrogen atom with a voltage
pulse from the STM tip [132].
1.3 Patterned Bonding between
Molecules and Surfaces
In this section,we will provide an overview of two
rather different methods of spatial control over molecular
bonding at surfaces.In Section 1.4.1,we will
discuss chemical chain reactions that lead to the
formation of molecular lines covalently bonded to a
silicon surface.In Section 1.4.2,we will discuss a
more general technique for molecular positioning
through the selective patterning of substrates to
delineate reactive regions on a surface.This
approach can be used to guide covalent molecule-
substrate bonding or to confine molecular
self-assembly to a predefined area.
1.3.1 Chemical Chain Reactions
Self-propagating directed growth via chemical chain
reactions represents an extremely appealing mechanism
for fabricating molecular architectures.As a
general schema,the growth of a molecular architecture
via a chemical chain reaction requires a
nucleation site,at which a molecule will attach in
such a way so as to create a second nucleation site.
Attachment of a molecule at this site will create a
third nucleation site,and so on.The power of this
technique lies in the simplicity of its execution: once
the initial nucleation sites are created,the subsequent
chemical chain reaction can be carried out quickly,
and in parallel,that is,the growth of multiple structures
can be carried out simultaneously.
The seminal work on molecular architecture formation
through a chemical chain reaction is described
by Lopinski et al.[133].The nucleation site for the
chemical chain reaction was a single silicon DB on an
otherwise H-terminated Si（001）.Figure 3 shows a
schematic of the reaction of an alkene at the DB site:
the alkene moiety（CH2TCH R）interacts with the
surface DB to form a C-centered radical at the carbon-
carbon double bond,and the radical abstracts a
hydrogen from a neighboring silicon dimer（this
mechanism was confirmed with density functional
theory modeling [134]）.After exposing a slightly
defective H:Si（001）surface to 3 l of styrene（1）,
Lopinski et al.observed molecular lines up to 130A°
in length.High-resolution imaging confirmed the spacing
of the features within the line to be 3.8A°,
corresponding to the dimer spacing on Si（100）.
The longest observed lines therefore indicate a
34- propagation of the chemical chain reaction.
Figure 3 Schematic illustration of an alkene reacting at a
silicon dangling bond in the first step of a chemical chain
reaction.From Lopinski GP,Wayner DDM,and Wolkow RA
（2000）Self-directed growth of molecular nanostructures on
silicon.Nature 406: 48-51.
Lopinski et al.essentially provided a recipe for
growing chain-reaction architectures.By changing
the substrate geometry or molecular substituents,
architectures with different geometries or functionalities
have been grown via the same principle.We
will discuss some of these below; for a discussion of
chemical chain reactions to produce molecular
monolayers,we direct the reader to a recent review
by Lopinski [135].
The growth of compact styrene islands was demonstrated
by exploiting the geometry of the H-terminated
Si（111）surface [136].In contrast to the unidirectional
propagation fostered on the dimer rows on H:Si（100）,
the H:Si（111）surface yields a（1-1）hexagonal array.
DB defects were created by selectively using the STM
tip to desorb hydrogen [137] from a high-quality
H:Si（111）surface created via wet-chemical methods
[138].Subsequent exposure to 12 l of styrene resulted
in the growth of a two-dimensional（2D）island at each of
the DB sites.The islands appeared to be self-limiting in
size,terminating after20 reactions,likely turning in on
themselves due to an attractive interaction between the
phenyl rings in the growing island.
Although island growth on Si（111）provides a neat
extension of the chemical chain reaction principle,
most efforts were directed toward growing linear
chains,which may play an important role in molecular
electronics,on Si（100）,the‘device’face of silicon.
The styrene chemical chain reaction proceeds
along a silicon dimer row,but growth across the
dimer rows has also been demonstrated [139].The
key to tailoring the growth direction lies in matching
the physical parameters of the reactant site in the
molecule with the periodicity of the silicon surface
（3.84A°
along the dimer row,7.68A°
across the rows）
[139].With styrene,for example,the Ccentered
radical abstracts a hydrogen from a neighboring
silicon dimer.However,for molecules where
R is CH2 SH,Hossain et al.[139] propose that the
C-centered radical can be transferred to the sulfur,
resulting in the creation of a thiyl radical.The thiyl
radical subsequently reacts with the surface to
abstract a hydrogen and create a new silicon DB.
Since it is located further from the anchored site of
the molecule,it is favorable for the thiyl to abstract a
hydrogen from the neighboring dimer row 5A° away,
rather than from the closer neighboring site along the
same dimer row.Figure 4 shows a schematic for this
reaction,together with an STM image of an allyl
mercaptan（2）line traversing the H:Si（100）dimer
rows.For comparison,the schematic and an STM
image of a styrene line are also shown.
2
In a follow-up work,Hossain et al.described a
beautiful experiment in which they interconnected
styrene and allyl mercaptan lines on the H:Si（100）
surface [140].Figure 5 displays a series of STM
images showing the steps involved.After creating a
H:Si（100）surface with a dilute concentration of DB
defects,lines were grown by exposing the surface to
5 l of allyl mercaptan.Using the STM tip,Hossain
et al.created a DB defect immediately adjacent to one
of the allyl mercaptan lines.This defect served as the
nucleation position for a styrene line,which,upon
exposure to 5 l of styrene,grew perpendicular to the
initial allyl mercaptan line,terminating at a parallel
adjacent line.
More recent work in this field has focused on
creating contiguous molecular lines incorporating
90  angles,a geometry potentially useful for molecular
wiring and electronics applications.It was demonstrated
that on the（3-1）-H:Si（100）surface the DB
terminating a styrene line could be used to seed the
growth of a perpendicular line of trimethylene sulfide,
creating a contiguous,L-shaped structure [141].Lines
comprising sections directed both parallel and perpendicular
to the（2-1）-H:Si（100）surface have also been
formed from a single molecule,acetophenone [142].
The capability for a single molecule to propagate via
chain reaction in perpendicular directions on this silicon
surface is unique,and the authors suggest that it
may be a manifestation of chirality effects in the
adsorbed molecule,together with the buckling of the
underlying silicon dimer [142].
1.3.2 Selectively Patterned Surfaces
An alternative route to guiding the bonding between a
molecule and substrate relies on the prepatterning of the
substrate through a preliminary process,such as the
growth of a specific surface phase.This can result in
the formation of spatially limited reactive zones on the
surface,and molecules introduced in a secondary
growth step will selectively bond to the reactive regions.
For this purpose,the Cu（110）/CuO surface provides
an ideal template.The reaction of even small
amounts of oxygen with Cu（110）produces a（2-1）
periodicity [143].The reconstruction,comprising
Cu O strings aligned along [001] and spaced by
two lattice constants（<0.512 nm）along [11ˉ0],is
formed from the chemisorption of oxygen with