PURPOSE: To enhance the effective sensitivity of a photosensitive material by installing a fluorescent-substance retaining structure which is arranged on the side opposite to the side where a means to generate an illuminating beam fir a mask structure for lithography use is installed and which includes a fluorescent substance and a fluorescent-substance retaining thin film to retain the fluorescent substance.

CONSTITUTION: A fluorescent-substance retaining thin film 2 composed of polyethylene terephthalate is pasted onto a ring-shaped retaining substrate 1; a fluorescent substance (e.g., BaSi2O5+Pb) 3 is sputter-evaporated onto the film. A fluorescent-substance retaining structure 3a which is constructed in this manner is arranged between a mask structure 10a for lithography use and a silicon wafer 12 coated with a resist 11. The assembly is illuminated with X-rays as an illuminating beam 6 from an X-ray source 4a as a means to generate the illuminating beam. Because the fluorescent- substance retaining structure 3a can be arranged on the side opposite to the side where the means to generate the illuminating beam for the mask structure 10a for lithography use is installed; i.e., in an arbitrary position between the mask structure 10a and the wafer 12, it is possible to arbitrarily set the strength of a fluorescent beam and to freely select the optimum condition for exposure.