Diffraction grating mfr. technique using irradiation of substrate

摘要

The procedure for the mfr. of an optical semiconductor device includes the stages of irradiation of a substrate (71) with the aide of a first (21) and a second (22) optical beam. These beams form interference fringes on the substrate which has a film layer (72) on its upper surface. The film is exposed by the radiation in order to form a diffraction grating mask on the surface as a result of the dual irradiation. The two sources of radiation are such that the wavefronts of the two beams intersect at the level of an intersection line (X) parallel to the substrate. The two beams pass through an optical element (20) which includes a smooth surface (20A) inclined w.r.t. a plane (20R) parallel to the substrate and following the line of the intersection.