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Method and apparatus for detecting the presence and thickness of carbon and oxide layers on EUV reflective surfaces

United States Patent

January 25, 2005
View the Complete Patent at the US Patent & Trademark Office
Sandia National Laboratories - Visit the Intellectual Property Management and Licensing Website
The characteristics of radiation that is reflected from carbon deposits and oxidation formations on highly reflective surfaces such as Mo/Si mirrors can be quantified and employed to detect and measure the presence of such impurities on optics. Specifically, it has been shown that carbon deposits on a Mo/Si multilayer mirror decreases the intensity of reflected HeNe laser (632.8 nm) light. In contrast, oxide layers formed on the mirror should cause an increase in HeNe power reflection. Both static measurements and real-time monitoring of carbon and oxide surface impurities on optical elements in lithography tools should be achievable.
Malinowski; Michael E. (Livermore, CA)
EUV, LLC (Santa Clara, CA)
10/ 163,477
June 5, 2002
This invention was made with Government support under Contract No. DE-AC04-94AL85000 awarded by the U.S. Department of Energy to Sandia Corporation. The Government has certain rights to the invention.