| 摘要 |
<p>PURPOSE:To obtain a photomask easily washable and repeatedly usable, and unaffected by dust attached to the surface of a transparent plate by thickening the peripheral part of a glass base so as not to focus the image of the dust attached to the transparent plate, on the base to be exposed. CONSTITUTION:A base 21 is made of glass or quartz, light interrupting films 22 are made of Cr or its oxide or the like, and the pattern of a circuit to be exposed is printed. The thickness of the base 21 is made thicker at the peripheral part than the inside by 3-6mm.. This thickness increase is executed on the outside of the pattern region and on the same side of the film 22. The section of the substrate as shown in the figure may be formed in one body, but since it is difficult to form it, and a considerable part of the material is wasted, glass or quartz is bonded with an adhesive to the part to be thickened. A transparent glass plate 23 made of glass is placed and in this state the photomask is set to an exposure device. As a result, the obtained photomask is easily washable, repeatedly usable, and not affected by dust attached to the surface.</p> |
