| AVS 65th International Symposium & Exhibition | |
| Extending Additive Manufacturing to the Atomic Scale Focus Topic | Wednesday Sessions |
| Session AM+NS+SS-WeM |
| Session: | Nanofabrication with Focused Electron Beams (8:00-10:00 am)/Atomic Scale Manipulation with Focused Electron Beams (11:00 am-12:20 pm) |
| Presenter: | Jason Fowlkes, Oak Ridge National Laboratory |
| Authors: | J.D. Fowlkes, Oak Ridge National Laboratory R. Winkler, Graz Centre for Electron Microscopy, Austria B.B. Lewis, Carl Zeiss Microscopy, LLC A. Fernandez-Pacheco, University of Cambridge L. Skoric, University of Cambridge D. Sanz-Hernandez, University of Cambridge M.G. Stanford, University of Tennessee E. Mutunga, University of Tennessee P.D. Rack, University of Tennessee H. Plank, Graz University of Technology, Austria |
| Correspondent: | Click to Email |
The deposition of complex 3D nanoscale objects with prescribed geometry and function constitutes a major goal of nanoscience. Additive assembly is the ideal approach to efficiently deposit 3D materials. Focused electron beam induced deposition (FEBID) is a resist-free, direct–write method suitable for the additive deposition of materials on both planar and nonplanar surfaces. During FEBID, a focused electron beam is scanned along the substrate surface inducing the deposition and condensation of absorbed precursor molecules, often an organometallic, delivered locally by an in-situ gas injector. Until recently, 3D deposition using FEBID was mostly a trial-and-error exercise lacking a reliable framework to deposit a wide range of geometries.
A design environment specific to beam induced deposition will be presented that has enabled the deposition of complex, 3D nanoscale mesh style objects spanning nanometer to micrometer length scales. A complementary 3D simulation of FEBID provides a predictive capability that aides in the design of more complex 3D deposits. The purpose of this design/simulation capability is to generate the primary electron beam coordinates and beam exposure dwell times necessary for the experimental deposition of 3D mesh objects, with a reduced fill factor, i.e., geometries required for the design of metamaterials, high–aspect ratio sensors/actuators and/or nanomagnetic/optical lattices.
The simulation reveals that precursor surface diffusion and electron beam induced heating, in particular, can impose unwanted mesh object distortions if not properly accounted for. This general rule applies for several precursors under picoampere, millisecond beam exposure using typical local precursor fluxes consistent with high vacuum scanning electron microscope operation. Compensation for these influences can be applied in either the CAD phase, as geometric distortions, or through the introduction of exposure pulsing which acts to mitigate the development of transient mass/heat gradients. The role of simulation in design will also be explained in the context of the proximity effect due to scattered electrons, specifically their role in inducing unwanted deposition. Simulation results are limited to cases where complementary experiments converge with simulated predictions in terms of the final deposit geometry and the electrical current collected dynamically during deposition.