On the top row are
two images of a nanomesh bilayer of PDMS cylinders in which the top layer
is perpendicular
to the complex orientation of the bottom layer. The bottom images show
well-ordered
nanomesh patterns of PDMS cylinders. The images on the right show
zoomed-in views of
the images on the left. Courtesy of the researchers
(January 22, 2016) Polymer
nanowires that assemble in perpendicular layers could offer route to tinier
chip components.
Since the 1960s, computer chips have been built using a
process called photolithography. But in the past five years, chip features have
gotten smaller than the wavelength of light, which has required some ingenious
modifications of photolithographic processes. Keeping up the rate of circuit
miniaturization that we’ve come to expect — as predicted by Moore’s Law — will
eventually require new manufacturing techniques.
Block copolymers, molecules that spontaneously self-assemble
into useful shapes, are one promising alternative to photolithography. In a new
paper in the journal Nature Communications, MIT researchers describe the first
technique for stacking layers of block-copolymer wires such that the wires in
one layer naturally orient themselves perpendicularly to those in the layer
below.
The ability to easily produce such “mesh structures” could
make self-assembly a much more practical way to manufacture memory, optical
chips, and even future generations of computer processors.
“There is previous work on fabricating a mesh structure —
for example our work,” says Amir Tavakkoli, a postdoc in MIT’s Research
Laboratory of Electronics and one of three first authors on the new paper. “We
used posts that we had fabricated by electron-beam lithography, which is time
consuming. But here, we don’t use the electron-beam lithography. We use the
first layer of block copolymer as a template to self-assemble another layer of
block copolymer on top of it.”