Determination of fluorochemical surfactants in acid etch baths by ion chromatography with on-line matrix elimination

Abstract

Fluorochemical surfactants are added to acid etching solutions to ensure good wetting of the wafer surface. Methods were developed to determine the fluorochemical surfactant FC-93 in an etch bath composed of HF–ammonium fluoride (1:6) and the fluorochemical surfactant FC-95 in an etch bath containing concentrated HF, HCl and HNO 3. On-line matrix elimination was accomplished on a polymeric reversed-phase column followed by separation on a multiphase HPLC column, and detection by suppressed conductivity. Using this method, we determined 5 mg/l of the surfactant FC-93 in 100 μl of the etch bath.