Pacific Nanotechnology Inc.
The machinery comprising the AFM can be utilized for active manipulation as well as passive
observation. That is, it can become a toolbox for altering the physical and chemical properties of
the SUT, not just a microscope. The tools in that toolbox include:
Like modern printing, nano-scale AFM
lithography uses one, or the other, or both of
the two basic techniques: bit-mapped imagery
and vector-drawn imagery. As in computer
printers, software renders the desired image
described by a source file (e.g. .bmp or .jpeg).
It moves the probe and indents, scratches, or
deposits "ink" of some kind (Figure 4-1). Resolution
of such AFM lithography, of course,
usually depends upon the probe diameter and
noisiness of the PZT positioning process. The
primary drawback to AFM lithography is low
scan rate.
Simple Scratching. What is a drawback for AFM microscopy can be an asset for surface
etching. If the force exerted by the
probe is high enough, and the SUT is
softer than the probe, the probe will
scratch the surface.
Anodic Oxidation. In 1989 it was demonstrated
that the localized current from a small probe, as
in a scanning tunneling microscope, can modify
a surface through localized electrochemistry.
The most common example is anodic oxidation.
In this particular example, the width of
the oxidized line that is created depends on the
number times it is traced.
Chemical deposition - The AFM as generalized printer/plotter. The AFM can be used as a sort of generalized
plotter, applying a variety of "inks" at the nanometer scale, for a variety of applications.
The vehicle for the deposition can be:
Many applications have been envisioned in which precise deposition or fabrication or lithographic
mask creation at the nano-scale are needed.
The fluid deposited may also be a so-called "molecular glue" which forms a template or mask for
subsequent chemical nano-scale fabrication.
Dip Pen Nanolithography® (DPN
®) is a proprietary scanning probe lithography technique invented
in Dr. Chad Mirkin's laboratory at Northwestern University, in which a microscopic pen (e.g. the
tip of an atomic force microscope cantilever) is coated with an "ink" (a chemical compound or
mixture) and put in contact with the "paper" (a substrate). Both the name and its abbreviation are
now trademarks of the Nanoink corporation. "Dip pen" is an archaic name for a quill pen, by analogy
to the procedure.
