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Clifford L. Henderson
Associate Professor
Contact Information
Building: Ford ES&T
Office:
1226
Phone: 404.385.0525
Fax: 404.894.2866
email
Mailing Address
Georgia Institute of Technology
School of Chemical &
Biomolecular Engineering
311 Ferst Drive, N.W.
Atlanta, GA 30332-0100
Links
Clifford L. Henderson
Education
B.S. 1994, Georgia Institute of Technology
M.S. 1996, University of Texas at Austin
Ph.D. 1998, University of Texas at Austin
Research Interests
Dr. Henderson's research interests are in the areas of polymer science, thin films, nanotechnology, organic electronic materials, and microsystems processing (i.e. the fabrication of microelectronic, optoelectronic, microfluidic, and microelectromechanical systems). The work in the Henderson group lies at the intersection of chemical engineering, polymer science, materials science, chemistry, electrical engineering, and nanoscience. The common themes throughout the work in his group are: (1) the rational design of novel materials and processes , (2) development of structure-processing-property relationships for the new materials developed in his group, (3) the development of models that can quantitatively describe the processing and properties of the materials developed in his group , and (4) the application of the group’s capability to fabricate materials and structures with control over their chemical and physical structure at lengths scales ranging from the molecular to the macroscale to solve engineering problems in a variety of current and emerging application areas. In terms of specific research and application areas, Dr. Henderson’s research group is currently working on the following topics: (1) understanding the physiochemical behavior of polymer ultra-thin films and nano-confined polymer structures, (2) development of novel membranes and membrane processing techniques for separations and fuel cells, (3) development of organic molecular glass photoresists for sub-32 nm node lithography in integrated circuit processing, (4) development of predictive mesoscale models for photoresist behavior during nanoscale patterning, (5) interfacial engineering of surfaces for semiconductor and organic solar cell fabrication, (6) novel routes for the production of graphene nanoribbons and nanostructures for electronics applications, and (7) methods for rapid manufacturing using stereolithography to produce complex three dimensional polymeric objects (e.g. contact lenses, tissue engineering scaffolds, etc.) . Additional details of a few of the specific ongoing project areas are provided below as examples of the types of work pursued in Professor Henderson’s group.
Polymer Ultra-Thin Films & Advanced Membranes: The behavior of polymeric materials can change quite dramatically as the materials are confined to small dimensions. The Henderson group has been one of the groups pioneering the discovery of which physiochemical properties in polymer ultra-thin films change due to nanoscale processing and confinement, characterizing what the important length scales are for observed deviations from bulk behavior with respect to different properties, and characterizing the magnitudes and potential universal scaling of such behaviors. For example, the group recently has presented results which show that the diffusion behavior in polymer thin and ultra-thin films formed by spin-casting techniques deviates strongly (e.g. a decrease in diffusion coefficient of up to ~5 orders of magnitude can be observed) from bulk polymer behavior when the film thickness decreases below approximately 2 microns in thickness. Such dramatic changes in diffusion behavior for polymer thin films has important implications in a variety of fields including microelectronics processing, fuel cells, and membrane based separations. Additional work is ongoing to exploit these observed changes in the physiochemical properties of thin and ultra-thin polymer films to develop materials with enhanced performance for such applications.
Advanced Materials and Processes for Semiconductor Patterning: There is a continuous drive in the semiconductor industry to shrink the size of device features such as the transistor gate in order to produce faster and more powerful microelectronic products. This aggressive schedule of feature size reductions imposes strong demands on the microlithographic technologies and imaging materials used to pattern semiconductor devices. A variety of projects are being pursued in the area of imaging materials (photoresists) that are directed at developing a fundamental understanding of the important physical and chemical processes that control their performance. For example, experimental and modeling studies are being pursued to understand the process of acid generation, simultaneous acid diffusion and reaction, and the polymer dissolution kinetics in chemically amplified (CA) photoresists. There is also a need to develop new imaging materials for next generation lithography systems (such as 193 nm, EUVL, and electron beam systems). Development of new “molecular glass” resists is being pursued in the group. Finally, entirely new fabrication and patterning processes are being developed in the group as alternatives to conventional subtractive lithography methods.
Development of Predictive Models for Molecular Glass Behavior: Molecular glasses refers to an exciting class of materials that are small molecule in nature but which produce amorphous films when processed. Such materials have application in a wide variety of areas ranging from organic light emitting diodes (OLEDs) to organic photovoltaics (OPVs) to semiconductor nanolithography. The Henderson group has been particularly interested in developing modeling tools that can be used during the molecular design process to predict the impact of chemical structure of a molecule on its resulting glass properties such as its glass transition temperature (Tg). A wide variety of modeling technique ranging from semi-empirical to detailed quantum chemical and molecular mechanics models are being used to develop the models of interest and the work is strongly coupled with experimental investigations to provide data sets for model creation and model validation.
Novel Routes to Manufacturing Graphene and Graphene Devices: Graphene can be thought of as a one atomic layer thick plane of a graphite lattice. This exciting new nanomaterial possesses an array of unique properties (e.g. ballistic conductivity) that make it a promising candidate material in a variety of electronic and optoelectronic applications. One of the potentially significant applications for the material is as a replacement for silicon in making high speed transistor based integrated circuits. Work in the Henderson group in this area is focused on the development of novel organic precursors and processing methods that will allow for the direct fabrication of graphene nanostructures in a manner compatible with existing microelectronics fabrication processes and materials.
Rapid Prototyping and Rapid Manufacturing using Stereolithography: Stereolithography (SL) refers to a set of techniques in which light is used to cause the photopolymerization of reactive monomer solutions to form three dimensional solid polymeric objects. The interest in this area for the Henderson group is in applying the group’s knowledge of photopolymerization characterization and modeling and the group’s materials design and synthesis skills to produce faster, more accurate SL processes in a wider variety of functional materials that can make an impact in the prototyping and rapid manufacture of constructs for a variety of applications including a recent focus on biomedical areas (e.g. hierarchically structured tissue engineering scaffolds and customized contact lenses).
Professor Henderson is a member of the American Institute of Chemical Engineers, the American Chemical Society, the International Society for Optical Engineering, the Materials Research Society, and the Electrochemical Society. He has authored more than 125 papers and holds 9 patents in areas related to his research.