Post-Plasma-Etch Residue Removal Using CO[sub 2]-Based Fluids

A high pressure CO 2 -based post-etch-residue removal method is described. Tetramethylammonium hydroxide (TMAH) mixtures containing methanol and water were used as cosolvents with CO 2 . 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 CO 2 at 3000 psi and 70°C was effective in removing the residue; under these conditions, more than one phase was observed in the CO 2 -based mixture. Mechanisms that account for the film and residue removal are proposed.