| 摘要 |
An exposure system which uses an optical system comprising optical elements having a magnesium fluoride film having an atomic ratio of magnesium : fluoride = 1.00 : 1.99 to 2.01. The magnesium fluoride film has an almost stoichiometric chemical composition and thus is almost free of the loss of fluorine, resulting in the suppression of the absorption of light caused by the loss of fluorine, which leads to the securement of a sufficient quantity of light for exposing a photosensitive substrate. The exposure system comprises optical elements having a magnesium fluoride thin film improved in the transmittance of a vacuum ultraviolet light. |
