| 摘要 |
PURPOSE:To enable detection of miniature flaws which cannot be observed heretofore by irradiating a light to the entire peripheral surface of the edge of a photomask. CONSTITUTION:Lamps 3 are confronted on the four end faces of a rectangular photomask 1 supported by guides 6 to irradiate the entire periphery of the end face of the mask 1 on a glass plate 2. When there are flaws 5 (A-C) on a metallic film 4, a light passing through the glass plate is refracted on the rough surface of the flaws 5 to leak on both the front and the rear surface of the glass plate. Since the light is not totally reflected on the flaws to increase the amount of the light passing through the flaw surfaces in this case, they can be easily observed on the main surface side. An observing area setting plate 7 perforated circularly at the center is fixed to the upper guides. The central circular portion of the plate 7 is coincident to the effective area of the photomask. By observing the area set on the plate 7, it can save the unnecessary inspection to improve the workability and can also clearly observe the flaws. |
