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In this paper, we describe a new method for creating nanostructures, and demonstrate its use by depositing Au, Ni, and Zn on a SiO2 passivated Si substrate. The method combined the spatial control of electron-beam lithography with the ease of fabrication of self-assembled arrays. The technique enabled the selective electrochemical deposition of nanostructures by creating specific nucleation sites by nanoindentation. This offered the possibility of accurately creating nanostructures ranging in size from one to hundreds of nanometers. We showed that it is possible to electrically isolate the nanostructures from the substrate and each other by a thermal oxidation process. In principle, this technique allowed fabrication of quantum devices of any geometry.

I. INTRODUCTION

The motivation for creating nanostructured materials has increased rapidly in recent years due to the unique quantum effects obtained at nanometer-length scales and the possibility of high-density electronic and photonic devices.1,2 Thus, both the fundamental research community and the semiconductor-processing industry have interest in such devices. The most well-developed method of fabricating nanostructures is electron-beam lithography (EBL).3 Although the process has the ability to create well-defined features below 100 nm, it also has many drawbacks. The most significant problem is, unlike regular photolithography, the individual components must be generated one constituent at a time. Thus, creating large numbers of functional components becomes time consuming and makes EBL too expensive for most processing applications. Another issue is that patterns larger than approximately 100 ␮m must be “stitched” together by moving the sample stage to a new position. This makes aligning structures that are only nanometers in size difficult, even when interferometric methods are used. Additionally, EBL requires many steps during which the entire surface must be subjected to deposition and removal of several polymeric and metallic films before the final pattern is generated. These drawbacks make EBL a complex timeand resource-consuming fabrication technique. In contrast to EBL, there are less-intensive methods that rely on the adsorption properties of certain species on particular substrates. These systems spontaneously order or self-assemble under certain conditions.4 – 8 Selfa)

Address all correspondence to this author. e-mail: [email protected]

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http://journals.cambridge.org

J. Mater. Res., Vol. 15, No. 12, Dec 2000 Downloaded: 14 Mar 2015

assembly enables the production of large arrays almost instantaneously. The fundamental drawback of these arrays is that their geometry is determined by the nature of the substrate and nanostructure material, making it almost impossible to manipulate the pattern formed. Although self-assembly technology is useful for applications where altering the relative positions of the nanostructures is not important, it is not as useful for high-density data storage and quantum computing devices. This paper describes a new me