Adsorption and Desorption of Cetyl Pyridinium Ions at a Tungsten-Coated Silicon Wafer Surface.

The use of surfactants to reduce the number of residual particles following chemical-mechanical planarization during integrated circuit manufacturing is relatively new. Recent results using cetyl pyridinium chloride and other cationic surfactant molecules show that surfactants are very effective in reducing the number density of residual polishing particles. The effectiveness of the surfactants is related to their ability to adsorb on the substrate surface. The contact angle and spectroscopic data in this study show that cetyl pyridinium ions can be readily adsorbed or desorbed from a chemical-vapor-deposited tungsten surface by controlling the concentration of other cations in solution. The mechanism for surfactant desorption is likely a competition between the cationic surfactant ions and other cations in solution. Copyright 1998 Academic Press.