SRT 2

Surface cleanliness

Main objectives are to develop knowledge on

• Qualification and characterization of the cleanliness of parts and materials for an EUV tool
• Carbon on multilayer mirrors
• Dominant mechanisms of contamination process
• The physics of removal of carbon from optical elements

During exposure of multilayer mirrors in EUV tools, contamination takes place. In contamination experiments it is observed that the dominant contaminants are condensable hydrocarbons that lead to carbonization. Therefore, extreme requirements on controlling the condensable hydrocarbons are set. In regular vacuum systems volatile species like water vapor and light hydrocarbons are governing the vacuum requirements and therefore in regular vacuum systems the focus is to volatile species. The research program consists of several topics on the cleanliness for condensable hydrocarbons in order to understand, limit and counteract the contamination process in EUV systems.