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 effectiven ess of the surfactants is related to their ability to adsorb on the substra te surface. The contact angle and spectroscopic data in this study show tha t 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 c ompetition between the cationic surfactant ions and other cations in soluti on. (C) 1998 Academic Press.