i) aproximación descendente ii) aproximación...

Bloque 4. Preparación de Nanomateriales

i) Aproximación Descendenteii) Aproximación Ascendente

Bloque 4: Preparación de Nanomateriales. Aproximación Descendente

Métodos Físico-QuímicosFotolitografía

Litografía de haz de electronesLitografía de nanoimpresión

Ciudad de Petra, 312 aC

Capital de los Nabateos

Aproximación de arriba-abajo (top-down)

Top-down

Botton-up

Litografía

AutoensamblajeSíntesis covalente

Estrategias para preparar Nanomateriales

Material Nanoestructurado

Herramientas en Nanotecnología

Bottom-up Top-down

Material Nanoestructurado Método descendenteMétodo ascendente

Método descendenteCrear objetos a partir de Macroobjetos

(Fotolitografía, nanolitografía,…)

Método ascendenteSíntesis Química-BioquímicaManipulación de átomos y

moléculas

Aproximación Descendente (top-down)

GraphenePotential

Applications

How Graphene can be synthesized?

exfoliation

Top-Down Bottom-up

CVD

Graphene

From GraphiteFrom carbon sources:

hydrocarbons, alcohols, carbon, ...

CVD: on Surface

polyethylene terephthalate (PET) substrate

Large Areas and transferred

Andrés Castellanos-Gómez, PhD Thesis 2011 UAM

Scotch tape exfoliation

Adhesivecontamination

Multilayergraphene

Few layergraphene

Graphene from Graphite: Micromechanical Exfoliation

Micromechanical Exfoliation with PDMS Stamps

Graphene from Graphite: Micromechanical Exfoliation

Micromechanical Exfoliation with PDMS Stamps

Andrés Castellanos-Gómez, PhD Thesis 2011 UAM

Graphene from Graphite: Micromechanical Exfoliation

Expansion of graphite

Graphene from Graphite: Chemical Exfoliation

Liquid Phase Exfoliation: Assisted by sonication

Electrostatic repulsion prevent re-aggregation

water suspensionstable for weeks

Surfactantdificult to

detach

SDS

Increasedexfoliation x20

With

NaO

HW

ithout

NaO

H

NMP

Suspension stablefor weeks

Solvent expensive and with high boiling

point 4 mg/mL6 mg/mL

F. Zamora et al. work under patent

0

0,2

0,4

0,6

0,8

1

230 430 630 830

THF-Water (4:1) - 0.5 ml in 2 ml ofsolvents

Liquid phase exfoliation of Graphite massive production

c 0.1 g/L

NMP

4003002001000

8

7

6

5

4

3

2

1

0

X[nm]

Z[n

m]

4 nm

(a)

(b)

(c)

(d)

Fuji Dimatrix materials inkjet-printer DMP-2800

Potential use as ink for a comercial inkjet printer

1.41.210.80.60.40.20

2.5

2

1.5

1

0.5

0

X[µm]

Z[n

m]

2.5 nm

3.532.521.510.50

14

12

10

8

6

4

2

0

X[µm]

Z[n

m]

6 nm

F. Zamora et al. work under patent

ca. 6 layers

Thomas Swan graphene scale-up

J. Mater. Chem., 2012,22, 8367-8371

Exfoliation: Assisted by Ball-milling

Evolución de la Fotolitografía

100 nm

Miniaturización de objetos

El toro micrométrico de Kawata,

del tamaño de los glóbulos rojos,

ha sido obtenido mediante

fotopolimerización de una resina

(Nature 2001).

Fotolitografía

Current Silicon Technology

Basic NanotechnologyTri-Gate Transistors

14 nm node

Fotolitografía

Resolución en Fotolitografía

Optics - Basics and Diffraction

• Ray tracing (assuming light travels in straight lines) works well as long as the

dimensions are large compared to .

• At smaller dimensions, diffraction effects dominate.

• If the aperture is on the order of , the light spreads out after passing through

the aperture. (The smaller the aperture, the more it spreads out.)

small Plane wave

continues due to

superposition

Spherical

secondary

wavelets - same

More

spherical

propagation

Aperture -

fewer

wavelets

Huygens-Fresnel principle

Free space

Small

aperture

Proceso de Fabricación

Various lithography sources

Contact Proximity Projection

MFS = (d.)1/2 ~ MFS = ((d+g).)1/2 ~ MFS = 0.61 /NA ~

Modos de Litografía Óptica

• Resist is in contact with the mask: 1:1 magnification• Advantages: Inexpensive equipment, moderately high

resolution (~0.5 mm or better but limited by resist thickness- 0.1 mm demonstrated)

• Disadvantages: Contact with the mask degrades the mask that results in non-uniform resolution, no magnification.

Difracción dela luz limita R

d

Resist is not in contact with the mask: 1:1 magnification

Advantages: Inexpensive equipment Disadvantages: Low resolution (~1-2 mm).

Diffraction effects limit accuracy of pattern transfer. Less repeatable than contact methods, no magnification

Mask image is projected a distance from the mask and de-magnified to a smaller image: 1:4 -1:10 magnification

Advantages: High resolution (25-14 nm), No mask contact(high production compatible). Magnification.

Disadvantages: Extremely expensive and complicated equipment, diffraction effects limit accuracy of pattern transfer.

Paso a paso

Resolución en Fotolitografía

Photolithography

apply resist

mask alignment/

exposure

develop

etching

resist removal

Resumen del proceso

SubWavelength Lithography

• Beginning in ≈ 1998, chip manufacturers began to manufacture chips with feature sizes smaller than the wavelength of the light used to expose photoresist.

• This is possible because of the use of a variety of “tricks” - illumination system optimization, optical pattern correction (OPC) and phase shift mask techniques.

(From Synopsis Website - www.synopsis.com)

Current Lithographic Technology

193 nm Excimer Laser Source

Computer Console

Exposure Column(Lens)

Wafer

Reticle (Mask)

www.tnlc.ncsu.edu/information/ceremony/lithography.ppt

• Lenses are very effective and perfectly transparent for 193nm and above, so many are used

• A single “lens” may be up to 60 fused silica surfaces

• System maintained at atmospheric pressure

• Lens NA ~0.5-0.85

• Up to 1.1 for immersion

• Exposure field 26x32mm

• Steppers capable of >100300mm wafers per hourat >100 exposures per wafer

Immersion lithography

R= K1 /NA

• 45-nm node (ASML)

Hyper-NA Immersion Litho Tool

From 1 cm to 1 nm

Brattain and Bardeen's pnp point-contact germanium transistor operated as a speech amplifier with a power gain of 18 on December 23, 1947

www.lucent.com 1 cm

First Nanotubes based transistor based on a CNT. Dekker group 1998

Moore Low(1964)Number of transistors will double every 18 months

Tra

ns

isto

res

po

rc

m2

Año

45 nm level

Intel® Core™2 Quad

45 nm10 nm

SELF-ASSEMBLY

LITHOGRAPHY

CONVENCIONAL

LITHOGRAPHY

nanopatterns.png

10 nm1010 componentes/cm2

Producción en laboratorio : 14 nm de sección de canal

Nanotecnología Básica

Current Silicium Technology

Basic NanotechnologyTri-Gate Transistors

14 nm node

Litografía de haz de electrones

Diferencias con la Litografía Óptica:

Longitud de onda de los electrones es menor

Los electrones presentan difracción despreciable (algo de scattering en la

resina)

Procedimiento de fabricación lento: no útil en producción

• Ventajas Mejor resolución

Escritura directa, sin mascara

Tamaño, forma y arquitectura arbitraria

• Inconvenientes Producción en serie

Areas pequeñas y lento

Scattering

Compatibilidad

Litografía de haz de electrones

• Fuente: electrones

• Voltage de aceleración Vc=120kV, λ=0.0336Å

• Utiliza una columna de electrones para generar

el haz

Litografía de haz de electrones

• Similar techniques to optical lithography: projection-printing

• Beam diameter 5 nm

• Can achieve a resolution of about 10 nm

• Limitation: secondary electrons…

surface gated quantum dot device

with submicron airbridge on

GaAs/AlGaAs

Litografía de haz de electrones

• (a) Sample is coated with a thin layer of a

polymer chemical known as the resist (ei.

polymethylmethacrylate, PMMA).

• (b) With EBL, there must be a path to ground for

the electrons. Thus, a small section of the

PMMA must be scraped away on the edge of the

sample so that conductive tape can be attached

from the sample to the stage (ground). If the

sample itself is an insulator, a very thin (10-20 Å)

layer of gold must be deposited onto the PMMA.

• (b) PMMA breaks down into smaller

molecular weight monomers upon exposure

to electrons. Afterwards, the exposed regions

can be rinsed away (developed) using a

chemical known as methyl-isobutyl-ketone.

• The rest is like optical lithography

Litografía de haz de electrones (EBL)

PMMA-polymetracrilato

Columna de electrones

Litografía de nanoimpresión

Preparación del sello

Impresión de patrones vía modo-estampa pre-diseñado

Polydimethylsiloxane (PDMS)

(a)(b) (c)

Stable for months

Nano-printing technology

• Si Stamp by e-beam lithography

• Polydimethylsiloxan (PDMS) stamp mat.

• OR add “ink” containing thiol molecules

• print on Si/ Au demosnstrated

• Structured SAM on Si/ Au (50 nm)

• Resolution depends on stamp and ink

Imprint mold with 10nm

diameter pillars

10nm diameter holes imprinted in

PMMA

10nm diameter metal dots fabricated

by NIL

Nanolitografía

Scanning Probe Lithography

• Probe

STM, AFM

• Techniques

Voltage pulse

CVD

Local electrodeposition

Dip-pen

Microscopias de Campo Cercano

Herramientas para la Nanotecnología

Scanning Tunnel

Microscope (STM)

Atomic Force

Microscope (AFM)

460nm

Ver

Manipular - Organizar

Medir Propiedades

Microscopio de Fuerzas Atómica (AFM)

(palanca)

(punta)

10-20 nm

Escribiendo con STM

• Examples of STM built

nanostructures with atom dragging

• Quantum corrals (diameter 14nm)

• Chains of atoms…other more

complex structures

• Ultimate in terms of resolution—

costly—slow

88

• Other tool is the Atomic force microscope

• The force between the cantilever and the sample is used to probe the

topography on the sample. Several modes of imaging to discuss later…

• Use conductive tip AFM as electron source for e-beam lithography

• Sub 50nm in commercial e-beam resist demonstrated

• SPM-based e-beam: less backscatter electrons

Quate and collaborators (Stanford)

Escribiendo con AFM

Dip Pen Lithography

90

AFM Dip Pen Lithography

• AFM tip is used to deliver molecules (Solvent meniscus)

• Naturally forms in the ambient atmosphere.

• Molecules anchor themselves to the substrate via

chemisorption

• Features as small as 15 nm linewidths

• and ~ 5 nm spatial resolution

• Chemical patterning of this sort can have a number of

applications

• Patterning conducting molecules, selective sites for

reactions, ….

Murkin Group