| 摘要 |
PURPOSE:To obtain a high-accuracy diffraction grating having a irregular pattern whose depth is controlled with high accuracy by detecting the ratio of the intensity of monitor light detected by a 1st photodetector ad the intensity of diffracted light detected by a 2nd photodetector. CONSTITUTION:A substrate 11 is irradiated with laser light at an angle theta of incidence from a laser light source 14 through half-mirrors 21 and 22, the diffracted light from the substrate is projected on a reference mark 24 formed on a screen 23, and a photodetector 15 detects light projected by a laser light source 14 as the monitor light. Further, a substrate holder 17 is lowered by a pulse stage 17 to dip the substrate 11 in an etchant 12, the light from the light source 14 is projected on a substrate 11A where the irregular pattern is formed at the angle theta of incidence through a half-mirror 21, and its diffracted light is detected by a photodetector 16. The diffracted light is compared with the monitor light detected by the photodetector 15 to accurately detect the depth of the irregular pattern. Consequently, etching condition such as etching time is determined based on the detection information to accurately control the depth size of the irregular pattern. |
