SUBSTRATE FOR PHOTOMASK BLANK OF RECTANGLE WITH SIDE OF AT LEAST 6 INCH USED TO EXPOSE PATTERN HAVING MINIMUM CHARACTERISTIC SIZE, AND PHOTOMASK PREPARED FROM THE SUBSTRATE

摘要

PURPOSE: Provided are a substrate for photomask blank which provides a photomask used to expose a pattern having a minimum characteristic size reduced with a high precision on a wafer substrate and shows a satisfactory flatness in exposure, and a photomask formed by patterning the layer of the photomask blank. CONSTITUTION: The substrate is a rectangle with a side of at least 6 inch and has a pair of band shaped regions spreading by 2-10 mm in the each inside of a pair of facing sides according to the outer circumference of an upper surface of a substrate wherein a mask pattern is to be formed except a 2 mm edge part to length direction from both terminal parts. The each band shaped region is sloped downward along the outer circumference of a substrate, and the difference between the maximum value and the minimum value to the height from the minimum square plane for the band shaped region on the upper surface of a substrate to the band shaped region is 0.5 micrometers or less.