FLUOROCARBON FILM AND RESIDUE REMOVAL USING SUPERCRITICAL CO_2 MIXTURES

摘要

A supercritical CO_2 based post etch residue removal method is described. To chemically attack the residue, tetramethylammonium hydroxide- (TMAH) based mixtures are used as co-solvents with CO_2. The effect of process parameters such as temperature, time, and co-solvent composition on the residue removal is investigated. X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) are used to characterize the samples. A 12% w/w of a 4:l volumetric mixture of 25% TMAH in methanol and de-ionized water in CO_2 at 3000psi and 70℃ was effective in removing the residue; under these conditions, more than one phase is observed in the CO_2-based mixture. Mechanisms that account for the film and residue removal are proposed.