| Abstract: 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. |
| Filed: 6/5/2002 |
| Application Number: 10/163477 |
| This invention was made with Government support under Contract No. DE-NA0003525 awarded by the United States Department of Energy/National Nuclear Security Administration. The Government has certain rights in the invention. |
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