OPTICAL ELEMENT, LITHOGRAPHIC EQUIPMENT HAVING SUCH OPTICAL ELEMENT, AND DEVICE MANUFACTURING METHOD

摘要

PROBLEM TO BE SOLVED: To provide an optical element, such as optical filter, optical diffraction grating, mirror, or lens, which is provided with a layer, having a small reflection for incident EUV radiation in the wavelengthλrange of 5 to 20 nm. SOLUTION: The optical element is equipped with a top layer which is transparent to an EUV radiation in the wavelengthλrange of 5 to 20 nm. The structure of the top layer has a root mean square roughness of not less thanλ/10 for a spatial period of not more thanλ/2. With such a configuration, transmission of the EUV radiation from the top layer to the optical element is promoted. COPYRIGHT: (C)2005,JPO&NCIPI