Polythiophene thin films have been deposited by a novel plasma technique which avoids the disadvantages of conventional plasma-based processes. In particular, the thiophene precursor is injected into an activated argon stream rather than into a plasma. The films produced are dense and uniform, with surface roughness of less than 1 nm. Other film properties are comparable to films deposited by more conventional methods. These films have been processed by reactive ion etching to produce micron-scale features.