Currently the most demanding application of extreme ultraviolet optics is connected with the development of extreme ultraviolet lithography. Not only does each of the Mo/Si multilayer EUV stepper mirrors require the highest attainable reflectivity at 13 nm (nearly 70%), but the central wavelength of the reflectivity of these mirrors must be measured to a precision of 0.001 nm and peak reflectivity of the reflective masks to a precision of 0.12%. We report on two upgrades of our NIST/DARPA Reflectometry Facility that have given us the ability to achieve 0.1% precision and 0.3% absolute accuracy in our reflectivity measurements. A third upgrade, a monochromator with thermal and mechanical stability for improved wavelength precision, is currently in the design phase.
Citation: Journal of Research (NIST JRES) -
Volume: 108 No. 4
NIST Pub Series: Journal of Research (NIST JRES)
Pub Type: NIST Pubs
extreme ultraviolet, lithography, metrology, reflectometry, synchrotron radiation