Dual-Fluid Spray Process for Particle and Fluorocarbon-Polymer Removal in BEOL Applications

Surface cleaning of patterned wafers by single wafer cleaning processing has become increasingly challenging as semiconductor fabrication makes deep inroads into sub-20 nm technology nodes. One of the most critical challenges for BEOL is a post-etch-residue cleaning in the trenches and vias without causing pattern damage and k-value change of low-k materials. Not only the chemical step but also rinse step is required to completely remove post dry-etch residue, which is fluorocarbon-based polymer residue in the structure. In this paper, a novel dual-fluid spray process for post-etch-residue cleaning has been developed. An optimized process could enable simultaneous higher particle removal efficiency and CF-polymer residue removal efficiency. A certain chemical/DIW mixture made smaller diameter droplets with higher velocities, in addition to excellent CF-polymer dissolved characteristics compared to conventional DIW Nanospray2.