University of California, Riverside

Department of Electrical and Computer Engineering

Assembly of block copolymers on chemically nanopatterned substrates: a platform for nanoscale lithography

Assembly of block copolymers on chemically nanopatterned substrates: a platform....


Paul F. Nealey

Department of Chemical and Biological Engineering
University of Wisconsin, Madison, WI 53706

When: Tuesday, May 12, 2009
Time: 2:00pm - 3:00pm
Location: A265 Bourns Hall


Information is encoded into the molecules of self-assembling materials such that they spontaneously form structures with well-defined dimensions and shapes at the nanoscale. In the particular case of block copolymer materials, thermodynamic driving forces for self-assembly are small and low-energy defects can get easily trapped. In order to take advantage of the self-assembling nature of block copolymers for lithographic applications, assembly must be directed to meet the severe constraints of manufacturing. Our approach to integrate block copolymers into and advance the performance of the lithographic process is to equilibrate films of block copolymers in the presence of lithographically defined chemically nanopatterned surfaces. Thus the starting point for directed assembly is chemical pre-patterns at or near the limit of current lithographic tools. In the form of thin films, surface and interfacial energy can be of equal or greater magnitude than the entropic (chain configuration) and enthalpic (block- block interfacial energy) contributions to the free energy that govern self-assembly in the bulk. Through tailored interfacial interactions between chemically patterned surfaces and the blocks of the copolymers, targeted block copolymer molecular weight and composition, judicious choice of surface pattern dimensions and geometry, and fundamental understanding of polymer chemistry and physics, we demonstrate that we can take advantage of the self-assembling nature of the block copolymer materials to enable resolution enhancement and precise control over the shapes (line edge roughness) and dimensions (critical dimension control) of patterned features, and at the same time retain the essential attributes of existing manufacturing practices including pattern perfection, registration and overlay, side-wall profile of features suitable for pattern transfer, and the ability to pattern device-oriented geometries.

About the Speaker:

Paul F. Nealey is currently the Shoemaker Professor of Chemical and Biological Engineering at the University of Wisconsin (UW), and is the Founding Director of the National Science Foundation-funded UW Nanoscale Science and Engineering Center in Templated Synthesis and Assembly at the Nanoscale. He graduated with his PhD in Chemical Engineering from the Massachusetts Institute of Technology in 1994, and from 1994 to 1995 he performed postdoctoral research in the Department of Chemistry at Harvard University. From 1995 until present, he has served on the faculty of the Department of Chemical and Biological Engineering at the University of Wisconsin. Paul F. Nealey's research interests include nanofabrication techniques based on advanced lithography and directed self-assembly, dimension dependent material properties of nanoscopic macromolecular structures, development of imaging materials for sub 50 nm lithography, and the effects of biomimetic nanostructured surfaces on cell behavior. He is a fellow of the American Physical Society, and has received the National Science Foundation Career Award, the Camille Dreyfus Teacher-Scholar Award, the University of Wisconsin Romnes Fellowship, and the Arthur K. Doolittle Award from the American Chemical Society.


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