Photoresist and Residue Removal Using Gas-Expanded Liquids

Abstract

Rapid technology development and demands for state-of-the-art generations of integrated circuits bring new challenges to microelectronic device manufacture. Specifically, decreasing dimension sizes may limit the effectiveness of liquid-based removal of photoresist and plasma etch residues. In addition, the hazardous solvents currently in use pose environmental concerns. Gas-expanded liquids (GXLs) and supercritical fluids may offer cleaning or residue removal approaches that overcome some of the drawbacks of current surface preparation methods. Removal of PHOST (polyhydroxystyrene) photoresist films has been demonstrated with -expanded ethanol (up to 75 mol % ), indicating that the inclusion of does not inhibit photoresist removal. In situ interferometry measurements of the PHOST layers allowed insight into the removal mechanism. The GXL mixtures were also invoked to remove post-plasma etch residues using -expanded . At a temperature of 90°C and pressures above 1000 psig the GXL mixture removed the photoresist and etch residue. Cleaning efficiency depended on pressure; at lower pressures the reduced the mole fraction of the while at higher pressures the assisted removal.