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Patterning at the Nanoscale: From Silicon to DNA
Co-Sponsored by the Electrical and Computer Engineering Department and the Maryland NanoCenter
Dr. Franco Cerrina
Electrical and Computer Engineering & Center for NanoTechnology
University of Wisconsin – Madison
December 7, 2007, 2:00 p.m.
Jeong H. Kim Engineering Building, Rm. 1110
ABSTRACT: In this talk I will present our research activity in the area of nanofabrication. I will review our work in the area of semiconductor lithography, showing the design and performance of our Extreme Ultraviolet Interference Lithography and Holography (EUV-IL and HL) setup operating at = 13.4 nm. This activity is geared to support the development of novel photoresist materials for the 50-10 nm domain lithography nodes of the ITRS. Many aspects of image formation involving EUV are still poorly understood, and in addition to the experimental work we have also developed an extensive set of simulation tools to model the image formation from aerial image to resist developed image. In particular, we include explicitly stochastic effects to model the Line Edge Roughness that affects severely the ability of current processes to pattern reliably below 50nm. Since EUV-IL generates patterns limited to periodic structures, we have also extended the application of holography to the EUV spectral range using Computer Generated Holograms (CGH) for arbitrary image synthesis; these holograms are particularly challenging to manufacture for use in the EUV because of the poor optical quality of the materials in that photon energy range.
It is a truism to say that lithographic patterning is an essential part of any form of fabrication process involving semiconductor technology. Interestingly, in recent years lithography has been extended to biological problems. A classical example is the activity at Affymetrix, where DNA microarrays are synthesized using a combinatorial sequence of exposures to yield “chips” with hundreds of thousands of pixels, each one corresponding to a unique oligomer sequence. These “Gene chips” are widely used in genomic research. The process has been further extended by our introduction of the “Maskless Array Synthesizer”, or MAS, in 2000. The MAS is commercialized today by NimbleGen-Roche for the rapid turnaround production of custom sequences of high density chips.
The application of lithographic techniques to biological problem does not stop with DNA microarrays. We are developing a “gene synthesis” process whereby the oligomers synthesized on-chip are harvested from the surface, amplified and stepwise assembled in longer constructs. These “synthetic genes” can be used to encode biological functions, or to enable the use of DNA as structural material. I firmly believe that the combination of high-resolution patterning (e.g., by E-beam lithography of functionalized surfaces) with on-demand synthesis of DNA (and other molecules) is paving the way to completely new applications. Thus, in summarizing my talk, I will put in context the merger of nanolithography (as a top-down technique) with DNA and other molecular synthesis (as a bottom up technique).
BIOGRAPHY: Franco Cerrina is Lynn H. Matthias Professor of Electrical and Computer Engineering at the University of Wisconsin-Madison. He is an IEEE, APS and OSA Fellow, recipient of the SRC Aristotle award, and the director of the Center for Nano Technology since 1988. He earned his Doctorate in Physics from the University of Rome in 1974 and joined the University of Wisconsin’s ECE Department in 1984. Since then, 23 Ph.D. students have graduated from his group. Over the years, he has procured and managed in excess of $45 millions in grants and research contracts. He has published over 250 papers and holds several patents.
His research work is centered on semiconductor fabrication, optical patterning and advanced lithography. Recently he has expanded his research to include the application of microfabrication techniques to biological and genomic problems. In this area he has developed a novel Maskless photolithographic method for the rapid synthesis of DNA microarray chips. This technique is being commercialized by NimbleGen Systems, a Madison (Wi) company of which he is one of the scientific founders and first VP of Engineering. He has also been a co-founder and CEO of Genetic Assemblies, Inc., a company dedicated to the synthesis of long DNA strands (synthetic genes) that has now merged with Codon Devices, Inc. of Cambridge, MA. He serves on NimbleGen Systems Inc. and Codon Devices Scientific Advisory Boards.
The activity of the Center for Nanotechnology (CNTech) focus on micro- and nano-lithography, with application to semiconductor processing as well as biological systems. The Center is an interdisciplinary research unit of the College of Engineering. More than 20 students and researchers use the Center’s resources at any given time. Under the direction of F. Cerrina, CNTech has become an internationally known research organization in the area of advanced semiconductor lithography and nanofabrication.
CNTech’s nanolithography activity is concentrated on Next Generation Lithography (NGL) development. CNTech is working closely with semiconductor industries and the federal government through grants and contract work. The biological activities focus on genomics problems, ranging from the development of novel techniques for high-density DNA microarray fabrication, to the de-novo synthesis of DNA.
His personal research interests are in the area of semiconductor processing and electron devices fabrication, including lithography, optics, X-ray optics and technology, and synchrotron radiation. This research has a strong applied content and is currently focused on manufacturing technologies for the sub-100 nm ULSI electron devices, such as post-optical lithographies. His activities include metrology, electron beam and extreme UV lithography (EUVL), and atomic force microscopy. Another focus of activity is in the computer modeling of optical systems (including X-ray optics) and of semiconductor lithography, where his group has developed codes that are now worldwide standards.
Faculty Host: Reza Ghodssi
This Event is For: Public • Clark School