Blanket tungsten deposition is used in the wafer processing industry to make via interconnects. The W etch back (WEB) process subsequently removes the W blanket film by an SF6 plasma treatment. WEB is a "dirty" process because, though the major etch product is gaseous WF6 (harmless), F . radicals and process by products attack chamber hardware, producing particles. In this study, these particles were characterized by using scanning electron microscopy/energy dispersive x-ray and Auger spectroscopy. A low-level, general surface contamination was also discovered using Auger. From this work, it was established that a major particle generation process involved etch by-product redeposition on, and attack of, Al chamber hardware. Based on this information, adjustment could be made to process conditions and chamber hardware which resulted in particle reduction to below specification levels.