| 摘要 |
PROBLEM TO BE SOLVED: To provide a glass substrate for a mask blank having high accuracy in measurement of flatness of a main surface and a manufacturing method for the same.SOLUTION: A glass substrate 10 for a mask blank has two main surfaces opposing to each other, where chamfered surfaces are provided around the main surfaces. Flatness of one main surface is equal to 100 nm or less, and in the one main surface and in the chamfered surface excluding a substrate corner part within a distance of 10 mm from an outer end in a two-dimensional projection shape of the chamfered surface 12 provided around the one main surface, a surge measured in an arbitrary 2-mm range in a direction parallel to one side of the two-dimensional projection shape immediately close to the chamfered surface is equal to 50 nm or less.SELECTED DRAWING: Figure 1 |
