The DACCLET research project (Dynamics of air entrapment in cooling circuits for lithographic exposure tools) is focusing on the development of a reliable calculation tool for air entrapment in cooling circuits for lithographic exposure tools. The project is a collaboration between Eindhoven University of Technology and ASML.
Thermal management of a lithographic exposure tool is essential for various key performance parameters e.g. overlay, imaging. Although next generation EUV tools can print much smaller features compared to earlier platforms, the energy efficiency has been significantly deteriorated. A high NA (Numerical Aperture) EUV tool takes a few hundred kW from the grid, whereas only a few watts end up as useful light at wafer level. All the heat that is lost on the way deteriorates the performance of the tool by various mechanisms e.g. mirror surface deformations, reticle heating, structure heating etcetera. Hundreds of liters of water are pumped to various components within the exposure tool every minute to minimize performance deterioration due to these heating effects. The downside of this high cooling flow is the deterioration of the dynamic performance as a result of forces that are created due to flow-induced vibrations.
Credits photo: ASML