| 摘要 |
PURPOSE:To perform focusing accurately by projecting a focusing incident light on a photomask for a semiconductor obliquely, making circuit the reflected light to a straight sensor and shifting the mask according to the detecting position of the sensor. CONSTITUTION:A semiconductor mask 7 on a holding stage is irradiated by an illumination light and image-formed on a pattern detector 1 through a lens 20. A laser beam 14 is projected on the mask 7 obliquely through a semitransparent mirror 16 and forms a light spot 21 through a lens 20. The reflected light of the light spot 21 is imaged on the position corresponding to the defocusing on a straight sensor 30 through the semitransparent mirror 16 and a filter 31 and the output is sent to a deciding circuit 50. The semitransparent mirrors 16B and 16D reflect the illumination light transmitted through the mask, a detection sensor 34 detects only the illumination light transmitted through a filter 33 and a deciding circuit 35 corrects the darkness of a pattern. The output from said circuit shifts the mask 7 vertically through a driving system 36 and a motor 5. Thus, focusing can be performed accurately. |
