Evaluating vacuum components for particle performance for EUV lithography

Mask blank defectivity remains a challenge in Extreme Ultraviolet (EUV) lithography. One of the mitigation strategies has been to identify the source of particles causing defects in the mask blank deposition tools. Vacuum components like valves, valve seals, stages, filters, etc. could be a possible source of particles in the tools. Therefore, it is necessary to quantify the amount of particles generated by the vacuum components. This feedback to the supplier can be used to help make vacuum components that shed fewer particles. We show results from a valve and nanoparticle particle test system at the College of Nanoscale Science and Engineering (CNSE) in collaboration with SEMATECH. The setup consists of a condensation particle counter (CPC), which can detect particles between 10 nm – 3 um, and a scanning mobility particle sizer (SMPS), which can provide the size distribution of the particles between 10 nm – 280 nm. We show results from testing two different types of 300 mm valves and compare the particle counts per cycle detected by the CPC for both. Moreover, choosing the best operating parameters of the valve can reduce the number of defects generated. We will present the optimized operating parameters. Selection of appropriate valve seal materials for plasma environments can also be crucial for reducing their degradation.