FIGS. 2A, 2B, 2C and 2D are views that illustrate the continuation of the process flow shown in FIGS. 1A, 1B, 1C, 1D, 1E, 1F and 1G. FIG. 3A is a view that schematically shows the optical system of an exposure device generally in use, and FIG. 3B is a view that shows the reflection spectra of two kinds of cold mirrors.