| 摘要 |
PROBLEM TO BE SOLVED: To withstand chemical and physical destruction on an optical device by providing it with a capping layer covering its surface on which a radiation with the same wavelength as the projection beam radiation is made incident and forming the capping layer with an inactive material. SOLUTION: On a substrate 10 contained in a reflection plate, a layer is deposited which comprises N cycles alternately consisting of a first material 11 and a second material 12. The last Nth cycle contains the first material layer 15, a third material layer 16 and a capping layer 17 composed of the capping material. The first material 11 comprises one or more out of Mo, Ru, Rh or the like and the second material 12 comprises one or more out of Be, Si, Sr or the like. For the last cycle, the first material is selected, and further the third material is selected from a set of materials known to be inactive and stable and having refractive indexes of ordinary values and sufficiently low absorption coefficients. The material for the capping layer 17 maintains high optical contrast between the layers 16 and 17 since the material has a low refractive index and Ru, Rh, Pd or the like is suitable for it. |
