Eletrochemical Microfabrication of Metalic Nanowires-A Revival of Electrochemical Methods for Modern Device Technologies?

摘要

Promising applications of electrochemical methods for modern device technologies already started in the 1960s. However, contamination problems usually ham- pered the applicability of, among others, electrochemical metal deposition. It is only recently that the miniaturization of electronic devices called for new technol- ogies for chip interconnects and electro- chemistry regained its importance in device fabrication. A damascene process, where copper is first electrodeposited onto the chip surface followed by a chemical- mechanical planarization proc- ess, yielded interconnects with unprece- dented quality}l] However, further minia- turization necessitates the development of new technologies for producing wires with a thickness of only a few nanometers. Recently Penner and co-workers from the University of California at Irvine met the challenge and introduced an electro- chemical method for the growth of met- allic nanowires of molybdenum on a stepped graphite surface, which exhibit electronic and mechanical properties sim- ilar to those of bulk materiaIJ2] In contrast to wires grown by, for example, step decoration on a surface by vacuum dep- osition of materials, these wires really extend into the third dimension. They exhibit hemicylindrical crossections with well defined diameters between 20 and 900 nm. The growth of such wires is a particular consequence of the electro-chemical deposition process:The wires grow by deposition of material directyly from solution,whithout any detour through adsorption and diffusion on the surface.THis leads ot multilayered,three-dimensional structures.