END GROUP EFFECTS ON ADHESION OF PERFLUOROPOLYETHER LUBRICANTS TO SOLID SUBSTRATES

Interfacial interactions of several commercial perfluoropolyether (PFP E) and aromatic-modified lubricants with silicon oxide or carbon subst rates were investigated through contact angle measurement, dipping tes ts, fluorescence spectroscopy and contact-start-stop testing. All comm ercial lubricants that have not been thermally treated are displaced f rom the solid substrate by contact with water. Contact angles of water on ZDOL, a PFPE doubly-terminated with hydroxyl groups, spun on silic on and carbon-coated wafers were measured as a function of thermal ann ealing treatment. The adhesion of commercial lubricants to such previo usly thermally-bonded layers is stronger than to the bare silicon wafe rs. The thermal reaction of ZDOL on silica gel and carbon was investig ated by thermogravimetric analysis and FTIR. The thermal reaction take s place when the baking temperature exceeds 70 degrees C; at least par t of this surface-bonding involves condensation of terminal hydroxyl g roups with isolated surface silanols. Finally, stiction values for aro matic-modified lubricants are substantially lower than for the unmodif ied commercial PFPE lubricants, but there are still significant humidi ty effects.