Tungsten (W) atomic layer deposition (ALD) was investigated on a variety of polymer films and polymer particles. These polymers included polyethylene, polyvinyl chloride, polystyrene, polycarbonate, polypropylene and polymethylmethacrylate. The W ALD was performed at 80 degrees C using WF(6) and Si(2)H(6) as the gas phase reactants. W ALD on flat polymer films can eventually nucleate and grow after more than 60 AB cycles. Xray photoelectron spectroscopy studies of W ALD on polystyrene after 50 AB cycles suggested that tungsten nanoclusters are present in the W ALD nucleation regime. The W ALD nucleation is greatly facilitated by a few cycles of Al(2)O(3) ALD. W ALD films were grown at 80 degrees C on spin-coated polymers on silicon wafers after 10 AB cycles of Al(2)O(3) ALD. The W ALD film was observed to grow linearly with a growth rate of 3.9 angstrom per AB cycle on the polymer films treated with the Al(2)O(3) ALD seed layer. The W ALD films displayed an excellent, mirror-like optical reflectivity. The resistivity was 100-400 mu Omega cm for W ALD films with thicknesses from 95-845 angstrom. W ALD was also observed on polymer particles after W ALD in a rotary reactor. Without the Al(2)O(3) ALD seed layer, the nucleation of W ALD directly on the polymer particles at 80 degrees C required > 50 AB cycles. In contrast, the polymer particles treated with only 5 AB cycles of Al(2)O(3) ALD were observed to blacken after 25 AB cycles of W ALD. W ALD on polymers may have applications for flexible optical mirrors, electromagnetic interference shielding and gas diffusion barriers. (C) 2007 Elsevier B.V. All rights reserved.