Skip to Main Content

Latest News

Advertise Here
January 31, 2011
Volume 89, Number 5
p. 11

Parallel Printing At The Nanoscale

Lithography: Simplified patterning method reproducibly yields thousands of copies

Mitch Jacoby

  • Print this article
  • Email the editor

Latest News

October 28, 2011

Speedy Homemade-Explosive Detector

Forensic Chemistry: A new method could increase the number of explosives detected by airport screeners.

Solar Panel Makers Cry Foul

Trade: U.S. companies complain of market dumping by China.

Novartis To Cut 2,000 Jobs

Layoffs follow similar moves by Amgen, AstraZeneca.

Nations Break Impasse On Waste

Environment: Ban to halt export of hazardous waste to developing world.

New Leader For Lawrence Livermore

Penrose (Parney) Albright will direct DOE national lab.

Hair Reveals Source Of People's Exposure To Mercury

Toxic Exposure: Mercury isotopes in human hair illuminate dietary and industrial sources.

Why The Long Fat?

Cancer Biochemistry: Mass spectrometry follows the metabolism of very long fatty acids in cancer cells.

Text Size A A

Tiny Tips Fabricated via photolithography and chemical-etching methods, the array of silicon tips supported on a springy polymer (shown in SEM images, top, and schematically) can be used to simultaneously draw thousands of identical patterns with features smaller than 50 nm. Chad A. Mirkin/Northwestern U

A novel scanning probe lithography method can simultaneously draw many thousands of patterns with features smaller than 50 nm, according to a study published in Nature by researchers at Northwestern University (DOI: 10.1038/nature09697). The work may lead to versatile and readily implemented procedures for making nanoscale components of electronic and biotechnology devices by providing tools and techniques that are simpler and less expensive than ones in use today.

A number of alternatives to costly commercial lithography techniques have been developed in recent years for patterning applications. Various types of microcontact printing and scanning probe methods, for example, have been demonstrated repeatedly. Yet these methods each exhibit some key drawback, such as depending on relatively complex tools or being limited in resolution, throughput, or breadth of application.

The new technique, which was developed by Northwestern’s Wooyoung Shim, Adam B. Braunschweig, Chad A. Mirkin, and coworkers, sidesteps many of those limitations. Dubbed hard-tip soft-spring lithography, the method is based on a cantilever-free array of pyramid-shaped silicon tips (4,750 in this demonstration) mounted on a compressible elastomeric layer. The tips’ hardness and roughly 20-nm diameter provide high spatial resolution, and the array design lends itself to scale-up and implementation with commercial atomic force microscopes.

The team made the array structures in a layer-by-layer fashion by using standard photolithography, masking, and chemical-etching procedures. In the finished product, the silicon tips rest on a silicon dioxide layer, which in turn is supported on a polymethyldi­siloxane-coated glass slide.

In one demonstration, the group quickly drew roughly 19,000 copies of the pyramid image shown on the U.S. $1.00 bill. The micrometer-sized patterns, which were drawn as bitmap images with 16-mercaptohexadecanoic acid “ink” on a gold surface, consist of closely spaced 40-nm dots. The team also drew patterns with polyethylene glycol on a coated silicon surface and imprinted a polymer film with ordered rows of 40-nm-diameter holes.

By exploiting the springiness of a soft polymer layer, the group has “introduced a clever way of eliminating cantilevers from a scanning probe experiment and, in the process, dramatically decreasing the complexity of the system and the cost of array fabrication,” says Joseph M. DeSi­mone, a nanopatterning specialist at the University of North Carolina, Chapel Hill.

DeSimone adds that this advance has a good chance of transitioning scanning probe lithography from primarily the domain of academic laboratories to an important production and prototyping tool broadly used across the semiconductor and biotechnology industries.

Chemical & Engineering News
ISSN 0009-2347
Copyright © 2011 American Chemical Society
  • Print this article
  • Email the editor

Services & Tools

ACS Resources

ACS is the leading employment source for recruiting scientific professionals. ACS Careers and C&EN Classifieds provide employers direct access to scientific talent both in print and online. Jobseekers | Employers

» Join ACS

Join more than 161,000 professionals in the chemical sciences world-wide, as a member of the American Chemical Society.
» Join Now!