RoWaFlowSim - Simulations of liquid film flows with free surface on rotating silicon wafers

SEZ AG develops and manufactures single-wafer wet-processing solutions for the global semiconductor industry. Their core technology is based on spin processing tools, which allow the introduction of specific cleaning, etching and stripping chemicals onto the semiconductor substrates (typically wafers). Numerous development issues, concerning the mechanics of fluids in motion, arise throughout the further progression of this technology. Therefore, CFD simulations have become an important tool to improve the understanding of processes and to optimize and advance the current technologies availableThe first subproject is related to the dynamics of the liquid motion on a rotating substrate. This includes phenomena, such as liquid film formation on a dry surface, wave propagation on the film, formation of hydraulic jumps, liquid impact and splashing on the substrate surface, as well as the detachment of liquid portions from the edge of the rotating disk. A design and computational tool for simulating the flow of liquid etching and cleaning media on the surface of rotating wafer disks will be developed. Due to the high complexity of the considered liquid flow with a free surface on the disk, numerical investigations and simulations require separate treatment of the various phenomena. The scientific partner for this subproject (FFG Fit-IT, ModSim) is the Institute of Fluid Mechanics and Heat Transfer (ISW) of Graz University of Technology (Prof. Brenn and Prof. Steiner). The second subproject is related to the transport of near-wall particles within the viscous sublayer of a laminar or turbulent boundary layer. Understanding of the initiation of particle motion will be developed through modelling and simulation and will cover particle adhesion and detachment from a substrate. This will lead to minimum drag and lift forces required to remove specifically nanoparticulate contaminants from a substrate. In addition it is expected, that it will be possible to make predictions regarding the average velocity of the particle after motion has set it. Based on the generated understanding larger scale flows will be engineered based on their underlying physical mechanisms. The goal is to be able to enhance the selectivity between removal of particulate contaminants and damage of nearly equally sized nanostructures. The scientific partner for this subproject is the Institute of Fluid Mechanics and Heat Transfer (ISW) of TU Wien (Prof. Kuhlmann). Implementation of the results will be done together with ICE Strömungsforschung GmbH.