Multiple Self-Aligned Iron Nanowires by a Dual Selective Chemical Vapor Deposition Process

Abstract

have also been reported. In this paper, we demonstrate a self-aligning technique that allows the fabrication of organized parallel iron nanowires on a planar edge silicon and silicon dioxide surface. The desired number of parallel wires is formed by repeating a series of polysilicon deposition and oxidation steps. The planarized surface for nanowire formation was defined by CMP and the iron wires were produced using a novel double selective CVD process. In this work, tungsten hexafluoride WF6 and iron pentacarbonyl FeCO5 were the respective tungsten and iron precursors. The dimensions and spacing of the iron wires were determined by the thickness of the thermal oxide and deposited polysilicon layer respectively, and not by any lithographic tool. Very accurate alignment was achieved with this method. The multiple iron nanowires proposed in this paper have possible applications in magnetic field measurement and calibration devices in pressure sensing where the resistivity of long thin iron resistors changes under stress. Possibly the most interesting application for this technology is in the formation of tunable diffraction gratings. Under the influence of an electromagnetic field, the properties of the iron will change, which may allow a switching mode in the grating. Figure 1 shows substrate preparation and the deposition of multiple parallel iron nanowires. 4 m deep trenches were etched into the silicon substrates in an inductively coupled plasma ICP system with SF6 and C4F8 plasmas Fig. 1a. The trenches were then refilled