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2007
Conference Paper
Titel
High-precision multilayer coatings and reflectometry for EUV lithography optics
Abstract
The topic of this paper is the fabrication and characterization of EUV reflective coatings based on molybdenum/silicon (Mo/Si) multilayers. For the fabrication of such nanometer structures, the technologies of magnetron sputter deposition (MSD) and ion beam sputter deposition (IBSD) are used in IWS Dresden. The main challenges for extreme UV (EUV) optics are high reflectance, precise thickness profiles, low internal stress and long-term stability. Reflectances > 70 %, uniformities > 99.9 % and overall internal stresses < 20 MPa have been reached. In addn. to sophisticated deposition technologies, precise metrol. tools are mandatory for the characterization of the coatings. Together with a no. of partners, IWS Dresden has developed a stand-alone EUV reflectometer that makes it possible to measure EUV reflectance R and peak position l on substrates with diams. of up to 500 mm. Current improvements of the reflectometer resulted in differences compared to calibrated measurements