AVS 56th International Symposium & Exhibition
    Advanced Surface Engineering Tuesday Sessions
       Session SE-TuP

Paper SE-TuP5
Novel Top-Down Fabrication Technique for Metallic Nanoparticles Using Microsphere Self-Assembly and Oblique Angle Thin Film Deposition

Tuesday, November 10, 2009, 6:00 pm, Room Hall 3

Session: Advanced Surface Engineering Poster Session
Presenter: M.A. Roddy, Rose-Hulman Institute of Technology
Authors: M.A. Roddy, Rose-Hulman Institute of Technology
E.M. Kirkpatrick, Rose-Hulman Institute of Technology
S.R. Kirkpatrick, Rose-Hulman Institute of Technology
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Metallic nanoparticles are of significant interest to the biomedical, electronics, optical, and magnetic fields. We have worked to develop a novel technique to fabricate nanoparticles on the order of 100 – 1000 nm. The process uses a self-assembled planar array of polystyrene microspheres[1] as a structured template for oblique angle deposition of a thin film, such that the tops of the spheres are covered with ‘caps’ (see Attachment 1). The spheres provide mutual shadowing from deposition, which determines the nucleation sites for metallization resulting in semi-spherical and hemispherical caps. Nanoparticle caps of both SmCo and chrome were fabricated. Chrome caps were prepared by allowing a mixture of 800 nm microspheres and DI water to dry on a substrate (glass, oxidized silicon, or bare silicon). 100 nm of chrome was then sputtered on the microspheres at angles of 80, 75, and 70 degrees normal to the surface. The sputtering parameters were base pressure of 2E-8 torr, sputter gas pressure of 2E-3 torr, and power of 300 W. In order to characterize the resulting nanoparticles via SEM the polystyrene was removed either by methanol or oxygen plasma ashing. A similar method was used for the SmCo samples, however, both an underlayer and overlayer of 15 nm NiCr was deposited head-on in order to prevent oxidation of the SmCo. Morphology of the samples depended on deposition angle and the deposition direction compared to the orientation of the self-assembled template and the resulting particles ranged in size from 350-700 nm.