A high pressure CO2-based post-etch-residue removal method is described. Tetramethylammonium hydroxide (TMAH) mixtures containing methanol and water were used as cosolvents with CO2. The effect of process parameters such as temperature, time, and cosolvent composition on the residue removal was investigated. X-ray photoelectron spectroscopy and scanning electron microscopy were used to characterize the samples. A 12% w/w of a 4:1 volumetric mixture of 25% TMAH in methanol and deionized water in CO2 at 3000 psi and 70degreesC was effective in removing the residue; under these conditions, more than one phase was observed in the CO2-based mixture. Mechanisms that account for the film and residue removal are proposed. (C) 2003 The Electrochemical Society.