| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an optical element which shows a good reflection characteristic over a long period of time in usage under extreme ultraviolet rays. <P>SOLUTION: A protection layer 30 is formed of a hydrogen-occluded alloy or of a material mainly formed of a hydrogen-occluded alloy. Hydrogen once accumulated in the hydrogen-occluded alloy is gradually emitted from the surface according to the environmental conditions such as temperature, however, the accumulated amount of hydrogen is kept at a prescribed level or above for a certain period. Since hydrogen in the protection layer 30 shows a strong reducing property, an oxidation reaction of the protection layer 30 and a multilayer film 20 below it which progresses under the extreme ultraviolet rays due to the existence of water and oxygen can be suppressed. In other words, it can be prevented that the hydrogen-occluded alloy which constitutes the protection layer 30 or molybdenum and silicon which constitute the multilayer film 20 is oxidized, leading to a decline in reflection factor of the multilayer film 20. <P>COPYRIGHT: (C)2006,JPO&NCIPI |
