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

Patent ·
OSTI ID:1175219
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.
Research Organization:
Sandia National Laboratories (SNL-CA), Livermore, CA (United States)
Sponsoring Organization:
USDOE
DOE Contract Number:
AC04-94AL85000
Assignee:
EUV, LLC (Santa Clara, CA)
Patent Number(s):
6,847,463
Application Number:
10/163,477
OSTI ID:
1175219
Country of Publication:
United States
Language:
English

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