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Autumn 2008 Seminar Series
Friday, November 7 at 3:30 p.m.
Room 264 MacQuigg Labs
Warren J. MoberlyChan
Lawrence Livermore National Laboratory
DualBeam SEM/FIB Applications & Prototyping Research: from cut-&-paste in the nano-kindergarten to see-&-do in the pico-preschool
Abstract
The advent of the two-beam tools (FIB/SEM) a decade ago dramatically expanded the utility of Focused Ion Beams beyond their historic roots as tools for semiconductor circuit-edit and TEM sample preparation. When using a focused beam or even trying to focus a beam, having a 2nd beam (such as SEM) of higher resolution to see what is being done with the first beam is invaluable; having an internal metrology tool provides the ultimate control to the processing capability of the tool. Furthermore, this in situ metrology results in on-the-fly decisions such that the SEM/FIB becomes the definitive prototyping tool for nanoscience; not just to micromachine a prototype part but also to prototype research itself; the ideal See-&-Do tool, not just do-&-see. In situ experiments are enhanced by add-ons such as: direct-write deposition systems, chemicals for enhanced etching, hot-&-cold stage, micromanipulators, electrical-&-optical contact/sensors, and detectors for other analytical techniques. With a 5-axis stage optimized for concentric/eucentric tilting, wide-ranges of 3-D processes become achievable in minutes. Consequently, we are learning more about the physics of ion beam processing, and these capabilities are then ported from the FIB back to large-beam ion-processing systems. The nano-nature of the FIB means expensive materials such as diamond or hazardous materials such as beryllium and uranium can be processed in very small quantities thereby reducing costs and human risk. The invention of 2-beam technology enables direct-write deposition of nanometer-scale devices using zeptoliter sources. And cryolithography has developed the most environmentally benign photoresist: ice. This talk discusses several wide-ranging applications of FIB: from TEM sample prep and lift-out extractions, to biological materials, to FIB's role in picoscale research (subnanosecond deformation, subnanosecond reactions and subnanometer structures). The 2nd part of the focuses on the ion beam process: to produce self-organized nanostructures, and to study "reverse reactions". In minutes the FIB/SEM produces a movie of the evolution of ripple topographies; with doses that typically require days in large ion-beam systems. Nanoscale observations of erosion have enabled us to control deposition during erosion, to produce picostructures. Conversely, erosion during deposition is controlled to "grow" ripples. The site-specific nature of the FIB leads to geometrical limits and boundary conditions. Although 14nm holes have pushed near-field optical microscopes to similar resolution (P. Stark), often it would be desirable to FIB etch a smaller hole or a deeper hole or even etch faster. Aspect ratio and redeposition are critical rate-limiting parameters for many applications; and the DualBeam allows us to study the 3-D erosion and deposition physics that are essential for nanostructure control. As we learn to understand and control reverse reactions that used to be declared as artifacts, we can begin to optimize their use in picotechnology.
Part of this work was funded by the United States Department of Energy at the Lawrence Livermore National Laboratory CMELS-MSTD contract of No. DE-AC52-07NA27344. (UCRL-ABS-236327)
Bio
Warren J. MoberlyChan is a microscopist in Boston, MA. He received his PhD in Materials Science & Engineering from Stanford University in 1991, and ScB from Brown University. His research has included high temperature structural ceramics and intermetallics and ion beam physics as a staff scientist at the Lawrence Berkeley and Livermore National Laboratories. He has worked in the Information Storage industry at ReadRite, Komag, Quantum, MPI, and SSL. He has taught Materials Characterization courses at Stevens Institute of Technology, San Jose State, Stanford, & Harvard Universities. His engineering interests are thin film interfaces and surfaces and the study of their chemical and mechanical properties through the application of microscopy, spectroscopy and FIB.
Please join our speaker for light refreshments in 479 Watts Hall following the talk.
