Adsorption of poly(oxyethylene) and hydroxyl group-containing nonionic surfactants on silica particles in NH4OH solution and its effect on the interaction force with Si surface
Year: 2023
Journal: Colloids and Surfaces A: Physicochemical and Engineering Aspects, Volume 674, 2023-10-05, page 131991
In the semiconductor manufacturing processes, surface cleaning is one of the most critical steps because particle contamination directly affects device yield. In addition, surface etching and oxidation should be minimized during the particle removal process. In this study, the dissolved oxygen concentration (DOC) in an NH4OH solution was reduced to suppress oxidation of Si. Additionally, nonionic surfactants were added to the solution to suppress the Si surface roughening and improve the particle removal efficiency in the NH4OH solution. Nonionic surfactant molecules were adsorbed on the Si surface, preventing the Si surface from attack by OH-. In addition, they were also adsorbed on the silica particle surfaces, producing repulsive hydration and osmotic forces between the adsorbed surfaces of the Si and silica particles while reducing the adhesion force between them. As a result, more than 95 % of particle removal efficiency and less than 0.6 nm of surface roughness were obtained when the particle-contaminated Si surface was treated with a low-DOC NH4OH solution containing a nonionic surfactant.
