The authors report successful patterning of transparent, conductive single-walled carbon nanotube films down to 100 nm lateral dimensions by photolithography or e-beam lithography and subsequent O-2 plasma etching using an inductively coupled plasma. reactive ion etching (ICP-RIE) system. They systematically study the effect of ICP-RIE etch parameters, such as substrate bias power, chamber pressure, and substrate cooling, on the nanotube film etch rate and etch selectivity. They also characterize the effect of the linewidth etched on the nanotube film etch rate for widths ranging from 50 mu m down to 100 nm. Furthermore, by fabricating standard four point probe structures using the patterning capability developed, the authors investigate the effect of different resist processes on the resistivity of patterned single-walled carbon nanotube films and the effect of ICP reactive ion etching on the resistivity of partially etched nanotube films. In addition, they demonstrate that using an ICP-RIE system provides significant advantages, such as faster etch rates and better etch selectivity, over conventional parallel plate RIE plasma systems, making it possible to pattern lateral features as small as 100 nm in nanotube films. The simple and efficient "top-down" patterning capability developed in this article could open up many opportunities for integrating single-walled nanotube films into a wide range of electronic and optoelectronic devices. (c) 2007 American Vacuum Society.