| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a method for selecting a substrate for a photomask blank resulting in a photomask with which a refined pattern can be drawn on a wafer substrate by exposure with high accuracy. <P>SOLUTION: In a pair of belt-like regions from 2 mm to 10 mm inside a pair of side lines opposing to each other in the side lines forming the peripheral edge of the upper face of the substrate where a mask pattern is to be formed, excluding a portion within 2 mm from both ends in the longitudinal direction, the height of the belt-like region from the least square plane of the belt-like region is measured at 0.05 to 0.35 mm intervals in the longitudinal and lateral directions. Then, a substrate for a photomask blank having ≤0.5 μm difference between the maximum and the minimum in the all measurement points is selected. The substrate selected by the method shows a favorable surface flat profile in exposing a wafer. By using the above substrate to manufacture a photomask blank and further processing the blank into a photomask, the photomask has little warpage of the substrate and high flatness when the mask is fixed by a vacuum chuck or the like to the mask stage of a wafer aligner. Therefore, a fine exposure pattern can be drawn on the wafer with accurate positions and width. <P>COPYRIGHT: (C)2005,JPO&NCIPI |
