| 摘要 |
PURPOSE:To form a diffraction grating only in the limited place by preparing a diffraction grating pattern by double-beam interference exposure of a photoresist on a substrate, coating a thin film thereon, windowing the thin film and further etching the substrate with the diffraction grating pattern as a mask. CONSTITUTION:The 1st photoresist 10 is coated on a substrate 1, and is subjected to double-beam interference exposure and development thereby preparing a diffraction grating pattern. The 2nd photoresist 11 which is different in a curing characteristic from the 1st photoresist is coated on such diffraction grating pattern. A mask 12 is then brought into tight contact with the photoresist 11 and is exposed, then the 2nd photoresist in the part right under a transparent part 14 is cured. Since the 1st photoresist under a light shielded part 13 does not receive irradiation of light, the diffraction grating pattern is not erased. If such resist is developed, the diffraction grating pattern is exposed in the windowed part A where the diffraction grating is ought to be prepared and the other part is covered B. When the substrate is etched further, the substrate in the part A is etched in conformity with the diffraction grating pattern. A diffraction grating 15 remains in a desired place when the resists 10, 11 are stripped. The diffraction grating is formed in a desired region at a desired size by the above-mentioned method. |
