WINDOW MASK FOR FORMING DIFFRACTION GRATING AND MANUFACTURING METHOD THEREOF

摘要

PURPOSE: A diffraction grating formation window mask is provided to decrease manufacturing costs by using a silicon substrate as an absorption layer and by forming a silicon nitride as a cut off layer. CONSTITUTION: Silicon nitride layers(11A,11B) are formed on the upper surface and the lower surface of a silicon substrate(10). An edge portion(10A) of the upper surface of the silicon substrate(10) covered with the laser beam cut off insulation layer(11A) supports a window mask(100). The center portion(10B) of the upper surface of the silicon substrate(10) enclosed with the edge portion(10A) is substantially used as a window mask. Cut off portions(12) and absorption portions(13) are repeatedly arrayed with stripe shape on the center portion(10B) of the upper surface. A concave not covered with silicon nitride layer(11B) is located on the center portion of the lower surface on the substrate(10).