In situ lateral patterning of thin films of various materials deposited by physical vapor deposition
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An approach to pattern directly thin films of various materials deposited by different physical vapor deposition methods is presented. Co and Ag films deposited by pulsed laser deposition and e-beam evaporation, respectively, were fabricated into 650- and 1000-nm-spaced parallel stripes on Si(100) surfaces by simultaneous two-beam ultraviolet laser interference irradiation of the substrate surface during deposition. The resulting morphology consists of 1- to 2-nm-height stripes, which have the same direction and spacing as the interference fringes. This approach has the potential to allow long-range ordering of well-defined patterns over large areas because the spacing and geometrical patterns are defined by the laser interference. Furthermore, the fact that this method works for different materials and does not require any lithography masks, etching steps, or substrate prepatterning, makes it promising as a simple and economical lateral patterning approach.
I. INTRODUCTION
Developing new approaches that allow practical control of material structure and morphology in the nanometer scale is of tremendous importance. One such area that requires techniques to manufacture controlled surface morphologies is that of nanostructured surfaces and thin films. Well-defined thin films and surfaces have extensive applications, such as the aligned template of catalysts (Fe or Co thin film) for the chemical vapor deposition growth of carbon nanotube arrays1 or ordered Si nanowires2 and the assembly of metallic and semiconductor nanocrystals on solid substrates for photonics and optical chemical sensing applications.3 Presently, lithography methods4,5 and self-assembly approaches6 offer the best opportunities to fabricate nanostructured surfaces. Laser precision microfabrication by atom-optical manipulation of neutral atoms, such as laser cooling7 or steering,8 are also promising fabrication methods. In this paper, we present results of a direct laser-assisted method to make controlled lateral surfaces on Si single-crystal substrates. We applied two-beam UV laser interference simultaneously with physical vapor deposition film growth and fabricated Co and Ag films into parallel stripes. The stripes have the same spacing and orientation as the interference fringes on the Si(100) substrate. Co stripes were fabricated during e-beam evaporation, whereas the Ag stripes were fabricated during pulsed
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Address all correspondence to this author. e-mail: [email protected] J. Mater. Res., Vol. 19, No. 2, Feb 2004
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laser deposition (PLD). The most likely mechanism for the resulting morphology is highly anisotropic surface diffusion and not preferential re-evaporation of the film material. No specialized processing steps, such as masking, etching, prepatterning, or seeding were used to achieve these patterns. These preliminary results suggest that the laser-interference modified growth method presented here may provide a simple and inexpensive way to fabricate controlled lateral
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