The 2012 Byron Bird Award
for Excellence in a Research Publication
Modern computer chips consist of millions of transistors assembled into intricate 3-D arrangements packed into tiny devices produced at rates of hundreds per hour. Improving these devices demands the ability to print ever-smaller structures — yet traditional ultraviolet lithography methods have reached their physical limit.
Over the past decade, Milton J. and A. Maude Shoemaker Professor of Chemical and Biological Engineering Paul Nealey has made seminal advances in nanolithography that have spawned a revolution in both the semiconductor device and hard disk drive manufacturing industries.
Published in 2003 in the journal Nature and cited more than 550 times, Nealey's paper, “Epitaxial self- assembly of block copolymers on lithographically defined nanopatterned substrates” (with Kim, Solak, Stoykovich, Ferrier and de Pablo), presented paradigm-shifting scientific and technological breakthroughs.
Nealey’s process sets forth an elegant method for organizing self-assembling block copolymer materials on surfaces such as silicon. He generates a lithographically defined chemical pre-pattern using traditional tools and materials, and then uses the pattern in surface wetting to direct the assembly of an overlying nanostructured block copolymer film. By manipulating the geometry of the chemical pre-patterns and the magnitude of interfacial interactions, block copolymer films are directed to assemble into two- and three-dimensional architectures that have a high degree of perfection and uniformity of dimensions — at resolution beyond that of the traditional lithographic materials and processes used to make the pre-patterns.
The approach overcomes limitations associated with traditional lithography and solves two outstanding problems — reducing the feasible feature size while still ensuring a perfect pattern over large, integrated surface areas — for the microelectronics industry. “The self-assembly of block copolymers on lithographically defined substrates is the cheapest, simplest and most elegant way to achieve the improvement in patterning resolution that is available today,” says C. Grant Wilson, a University of Texas at Austin professor of chemical engineering.
Nealey's 2005 Science paper, “Directed assembly of block copolymer blends into non-regular device-oriented structures” (with Stoykovich, Muller, Kim, Solak, Edwards and de Pablo), as well as dozens of other articles he and colleagues have published in leading journals, continue to detail advances that have made block copolymer lithography a part of the International Technology Roadmap for Semiconductors. “Convincing several large industrial giants to adopt a radically new fabrication technology is no small feat, and should be viewed as the ultimate achievement for an engineer,” says Nicholas Abbott, John T. and Magdalen L. Sobota Professor and chair of chemical and biological engineering at UW-Madison. “Through his 2003 Nature paper and his 2005 Science paper, Paul Nealey did that at a very early stage in his career.”