PRODUCTION OF DIFFRACTION GRATING

摘要

PURPOSE:To enable the easy production of a diffraction grating of short periods by use of a two-beam interference exposing method by forming patterns alternately disposed with high and low flat parts on a substrate and forming a coating layer having the property of the etching rate higher on step parts than on the flat parts thereon. CONSTITUTION:The diffraction grating pattern alternately formed with the high flat parts 3a and the low flat parts 3b is formed on the surface of the substrate 3. The coating layer 4 having the property of the etching rate higher on the step parts 3c than on the flat parts is then formed on the substrate 3. The coating layer 4 is thereafter etched to remove the coating layer only on the step parts 3c and the regions near the same. The etching progresses only in the step parts 3c when the substrate 3 is etched with the coating layer 4 remaining on the high flat parts 3a and the low flat parts 3b as a mask. The diffraction grating 5 having the period of half the period of the diffraction grating patterned on the substrate 3 is thus obtd.