Mitigation of reduce of hydrocarbon contaminants for EUVL

Under EUV radiation, the surfaces of the imaging optics and mask, which are coated with a Mo/Si multilayer, become contaminated with organic compounds. So, we have to decrease the hydrocarbon species in the vacuum chamber. For that purpose, we choose the low outgassing materials used for vacuum components: stages, sensors, wires and so on. There is a great deal of data on outgassing from the materials of vacuum components during baking. However, baking is not feasible for an EUV exposure tool because this apparatus contains many parts and optics that are aligned very precisely. So, outgassing from the materials used for vacuum components was examined without heating.