Polymer-based semiconductor wafer cleaning: The roles of organic acid, processing solvent, and polymer hydrophobicity

Abstract

We propose a novel polymer-based cleaning technique to remove nanoparticles (<100 nm) from high-k and low-k wafers. Our method involves applying a polymer solution containing a hydrophobic polymer and organic acid onto the wafer surface, resulting in the formation of a nanoparticle-containing polymer film that can be peeled off. To ensure gentle removal of the film without wafer damage, we have developed a water-based “flake” method. Water penetrates the film through the organic acid, producing fine polymer flakes that can be easily removed along with the nanoparticles. Our systematic cleaning experiments involving diverse polymers, organic acids, and solvents on various nanoparticles and wafers demonstrate that polyvinylidene fluoride, a polymer with low surface energy, is exceptionally effective in nanoparticle removal due to its hydrophobic properties. Furthermore, it exhibits significant flake generation when exposed to water, thanks to its polymorphic characteristics, thereby exerting the most potent polymer-based cleaning effect. These experimental findings are consistent with our thermodynamic model simulations. This polymer-based cleaning technique provides a feasible solution to the long-standing environmental concerns associated with conventional semiconductor cleaning processes.