MASK DEFECT INSPECTOR

摘要

PURPOSE:To achieve highly accurate inspection free from a false defect, by carrying out an inspection of a detect of a mask or the like by a hologram. CONSTITUTION:This inspector has hologram synthesized with a computer (CGH)7, and object lighting light 9, reflecting mirrors 12 and 13, beam magnifying mirrors 14 and 15, an object light 30 to be measured, a reference object light 31 and the like. A laser light from a laser source 8 is divided into two optical paths with the half mirror 11 and one of them turns to a lighting light 9 of a mask 1 expanded by magnifying mirror 14 through the mirror 13. The object light 30 of a mask 1 thus lighted reaches an observing point 32 directly. The other thereof is expanded with a magnifying mirror 15 through a mirror 12 to turn to a reproduced light 10 of the CGH7. Thus, the first light reaches the observing point 32 being interfered with the object light 30 from the CGH7 thus reproduced. As a result, for example, a defect exists in a mask, an interference fringe is developed by the object lights 30 and 31. A defect on the mask can be detected by observing this interference fringe.