Polishing method of square photomask substrates, square photomask substrates, photo-mask blanks and photomasks

摘要

PROBLEM TO BE SOLVED: To improve flatness of a substrate by applying the pressing load to an entire guide ring during grinding separately from the substrate to be ground, and to consistently provide flat substrates. ;SOLUTION: In this square substrate grinding method for grinding the square substrate having the square shape of the substrate to be ground, a surface to be ground of the substrate held in the guide ring of a substrate holding head having the guide ring is pressed against a grinding cloth, the guide ring is pressed against the grinding cloth, the grinding cloth, the substrate holding head and the substrate are rotated respectively, and the surface to be ground of the substrate is ground while pressing the grinding cloth by a grind head pressing surface of the guide ring.;COPYRIGHT: (C)2003,JPO