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Introduction to Nano-fabrication Jared Kroke

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Jordan Iverson

on 6 December 2012

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Transcript of Introduction to Nano-fabrication Jared Kroke

Bottom-up Top-down Introduction to Nanofabrication Nanotechnology is Impacting Everything http://www.cvrick.com/cv_rick/images/2007/09/22/tiny_01.jpg Making nano-scale "things" is called Nanofabrication There are 3 different approaches to Nanofabrication: 1. Top-down nanofabrication

2. Bottom-up nanofabrication

3. Hybrid nanofabrication Nanotechnology uses Nanofabrication to make a wide variety of Nano-structures: 1. Nano-particles
(e.g., macro-molecules,
beads, tubes, wires)
2. Planar structures
(e.g.,structures built
using layers)
3.Hybrid structures (mixtures of particles
and planar structures) http://static.guim.co.uk/sys-images/Guardian/Pix/pictures/2008/05/20/nanotube.article.jpg http://2.bp.blogspot.com/_wkhzIFfw_Qo/SMltRMfaAWI/AAAAAAAAASs/bPzfhcn7cvw/S660/Planar+structure+by+Joy+Lee,+2004.jpg How are these things made: 1. Top-down nanofabrication makes nano-
structures by repeated use of steps that put
down films and take parts of them away

2.Bottom-up nanofabrication builds up nano-
structures from atoms, molecules, particles, or
some combination of these

3. Hybrid nanofabrication combines elements of
top-down and bottom-up nanofabrication How do you direct Nanofabrication? 1. Sometimes no direction is
needed; i.e., no patterns for
establishing positioning are
required (e.g., nanoparticles in solution)
2. Sometimes direction is required; i.e.,
sometimes patterns for positioning are
necessary (e.g., transistors on a
substrate)
3. No external pattern control; Hybrid When Pattern Controlled Fabrication is required, it can utilize an: 1. Externally Imposed Pattern (This
approach is generally called
lithography)
2. Inherent Pattern (Uses size,
shape, or chemical bonding to
impose patterning)
3. Hybrid (mixture of both)

4. No external pattern control;
Hybrid External Patterning means: 1. Using lithography for placing,
growing, or modifying materials into
patterns, where you want, on a
structure on a substrate

2. Using lithography for removing
materials, where you don't want them,
on a structure on a substrate An Example of An Externally Imposed Pattern (Lithography) Pattern is transferred from a “mask” using
light (photolithography) in this example Pattern is
external to
structure. It is
originally here
(on what is called a “mask”) Fabrication is done here following the transferred pattern Pattern is transferred to here (in this caseby using a material that is sensitive to light) Inherent Patterning means- 1. Using size, shape, specific chemical
bonding or all of these to establish a
pattern in the nanofabrication

2. No external pattern control;
Hybrid An Example of An Inherent Pattern Pattern is dictated by shape and chemical bonding in this example Antigen “fits” into antibody due to shape, size, and specific chemical bonding and self-assembles Antigen Antibody Top-Down Nanofabrication is like sculpting Start with a material supported on
a substrate Add some new material
according to a pattern (lithography) Image courtesy of Bruce Hirst Image courtesy of Bruce Hirst Top-Down Nanofabrication is like sculpting Subtract some of the material
according to a pattern (Process
order is not important; can subtract
before or after adding) Repeat the adding/subtracting as
needed following the pattern Image courtesy of Bruce Hirst Image courtesy of Bruce Hirst Bottom-up Nanofabrication is like putting blocks together The building blocks can go together in some inherent

pattern dictated by shape or

they can go together randomly The building blocks can be atoms, molecules, or nanoparticles Vs. Top-Down: In “top-down” nanofabrication, one grows or deposits layers of materials and, by some combination of physical and chemical methods, creates the desired nanostructure. Structures of carefully controlled, limited dimensions are created by laying down layers of material, modifying properties as needed, and etching away those parts of each layer that are unwanted. Bottom-Up: In “bottom-up” nanofabrication approaches, one starts with small components – for example, individual molecules and nano-particles – and then assembles these components to make the desired structure. The basic materials of top-down nanofabrication
are layers (e.g., films) of materials. The basic materials of bottom-up nanofabrication
are atoms, molecules, particles, and layers. Top-down Nanofabrication always

uses some combination of- 1. Lithography (Pattern Transfer)
2. Growth/Deposition (Addition process)
3. Etching (Substraction process)
4. Modification
5. No external pattern control; Hybrid Here’s the way Top-down
Nanofabricaton is done – 1. The four steps (lithography, addition, subtraction
and modification) are used in some sequence.

2. Steps may be skipped. You can start with any step.

3. The sequence usually starts with growth or
deposition of material.

4. Lithography is the step which orchestrates all the
others. It controls where materials stay and where
they are “sculpted” (i.e., etched) away. The Top-Down
Fabrication
Method Depositing
or
Growing Material
Modification Etching Lithography Hybrid Hybrid Bottom-up Nanofabrication always
uses some combination of- 1. Building block (molecules, particles,
and layers) fabrication

2. Self-assembly Here’s the way Bottom-up
Nanofabricaton is done – 1. The two steps (building block fabrication
and self-assembly) are used in some sequence.
2. Steps may be skipped.
3. The sequence starts with building block
fabrication.
4.An inherent patterning process (due to size, shape, chemical bonding) may be present. The Bottom-up
Fabrication
Methodology Building
Block
Foundation Self
Assembly An Example of a Bottom-Up
Nanofabrication Processing Sequence Synthesize Nanoparticle Functionalize the Nanoparticle Link with Antibodies Antigen Attachment Courtesy of CNEU Copyright April 2009 The Pennsylvania State University The preceding cartoon demonstrates
the two basic steps of bottom-up
nanofabrication: 1. Building Block Fabrication (molecules,
particles, or layers--the basic building blocks
of bottom-up nanofabrication)
2. Assembly of the building blocks into functioning nanostructures.
3. In this example, an inherent pattern was present dictated by allowed chemical bonds Key Points 1. Making of nanostructures is nanofabrication. 2. Two types of nanofabrication:Top-down and Bottom-up. 3. Combination of the two is called Hybrid. 4. Top-down makes structures from layers using addition/subtraction processes guided by a pattern established by lithography. 5. Structures of carefully controlled, limited dimensions are created by laying down layers of material and etching away those parts of each layer that are unwanted in Top-Down fabrication. 6. Bottom-up assembles building blocks. Can be random or follow pattern present due to bonding, size, or shape. 7. Bottom-up uses atoms, molecules, and nano-particles
assembled to make a desired structure. This module, produced by the Center for Nanotechnology Education and Utilization at
The Pennsylvania State University,
is one of a series developed to introduce nanotechnology and its applications to a broad audience. Each module, its component viewgraphs, and the companion glossary are copyrighted 2009 by
The Pennsylvania State University.
All rights reserved.
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