| 摘要 |
PURPOSE:To obtain the method whereby a mask plate easily mounted and detached is prevented from curving while it is polished, by securing a mask in its peripheral part without a thin film by vacuum attraction facing a surface of the mask downward and supporting the central part with a thin film by a stable liquid holding layer of small compressibility so as to polish the reverse side. CONSTITUTION:A supporting bed 5 provides a vacuum chamber 6 for a vacuum attracting means because no thin film is provided in the peripheral part of a mask transparent base plate 1, and the vacuum chamber 6 additionally provides a vacuum attracting pipe 7 to obtain a securing pressure a little less than 1kg/cm<2>. While a central part 2, in which a light-shielding pattern thin film 3 is positioned facing downward, is filled with liquid of small compressibility in the inside as a holding layer 8, and the holding layer 8 additionally provides a supply pipe 10 and a discharge pipe 11 supplying and discharging the liquid through pressure valves 9, 9', adjusting the liquid in the holding layer 8 so as to be maintained in a fixed quantity. Then the reverse side of a mask is polished by a polishing wheel 12, and the mask after the completion of its polishing can be easily detached from the supporting bed if the atmosphere is returned into the vacuum chamber further the liquid is introduced at a slight pressure into the holding layer. In such way, the mask can be polished without causing a curve. |
