| 摘要 |
PURPOSE:To prevent a transparent glass base plate 1 from the generation of ''sunburn'' or ''spots'' and the adhesion of foreign substances or dust during the keeping period of a photo mask by covering the surface of the photo mask by a protection film. CONSTITUTION:A photo mask having opaque thin layer patterns 2 on the surface of a transparent glass base plate 1 which can transmit light is covered with a protection film composed of resin such as PVA, epoxy resin and resist to keep it. Thus, the photomask is protected from the direct exposure to air, preventing the generation of ''sunburn'' or ''spots'' due to the separating of sodium in the glass on the surface of glass as sodium carbonate or the change of refractive index which is caused by the penetration of hydrogen ions into the glass from which metallic ions have been separated and also preventing the surface of the mask base plate from direct adhesion of foreign substances or dust during the keeping period of the photo mask. |
