Top Down and Bottom Up Construction NanoFabrication Techniques Defined

Topics Covered

Background

Top Down Fabrication

Top Down Fabrication Techniques

Bottom Up Fabrication

Bottom Up Fabrication Techniques

Background

Fabricating structures at the nano level can be broken down into two main methods; top down and bottom up construction.

Top Down Fabrication

Top down fabrication can be likened to sculpting from a block of stone. A piece of the base material is gradually eroded until the desired shape is achieved. That is, you start at the top of the blank piece and work your way down removing material from where it is not required. Nanotechnology techniques for top down fabrication vary but can be split into mechanical and chemical fabrication techniques.

Top Down Fabrication Techniques

The most top down fabrication technique is nanolithography. In this process, required material is protected by a mask and the exposed material is etched away. Depending upon the level of resolution required for features in the final product, etching of the base material can be done chemically using acids or mechanically using ultraviolet light, x-rays or electron beams. This is the technique applied to the manufacture of computer chips.

Bottom Up Fabrication

Bottom up fabrication can be likened to building a brick house. Instead of placing bricks one at a time to produce a house, bottom up fabrication techniques place atoms or molecules one at a time to build the desired nanostructure. Such processes are time consuming and so self assembly techniques are employed where the atoms arrange themselves as required.

Bottom Up Fabrication Techniques

Self assembling nanomachines are regularly mentioned by science fiction writers but significant obstacles including the laws of physics will need to be overcome or circumvented before this becomes a reality. Other areas involving bottom up fabrication are already quite successful. Manufacturing quantum dots by self-assembly quantum dots has rendered the top down lithographic approach to semiconductor quantum dot fabrication virtually obsolete.

Source: AZoNano

For more information on this source please visit AZoNano

 

Date Added: Jan 25, 2007 | Updated: Jun 11, 2013
Comments
  1. ஆனந்தம் ராஜ் ஆனந்தம் ராஜ் India says:

    Very effective and easy to learn!

The opinions expressed here are the views of the writer and do not necessarily reflect the views and opinions of AZoNano.com.
Tell Us What You Think

Do you have a review, update or anything you would like to add to this article?

Leave your feedback
Submit