Abstract: A method for manufacturing a glass substrate by a fusion process includes flowing fused glass into a fusion pipe, and gradually cooling and solidifying the fused glass by allowing the glass to flow downward from the fusion pipe. An asperity is formed on a surface of the glass substrate by fastening and pressing the glass toward a direction of thickness of the glass with a pair of transfer rollers while the glass is flowing down from the fusion pipe.

Abstract: A photomask substrate with a substantially uniform thickness comprises: a first surface, which is a continuous curved surface whereon a mask pattern is to be formed; and a second surface. The first surface exhibits a square shape that comprises an opposing pair of first set sides and an opposing pair of second set sides and has support parts at end parts along the first set sides. When the photomask substrate is held such that the first surface is in a substantially vertical state, a reference plane that is parallel to a tangential plane of the first surface at the center point of the first surface is defined on the photomask substrate side that is closer to the first surface than to the second surface. At this time, a first distance in the thickness direction between the reference plane and the center point of the first surface is shorter than second distances in the thickness direction between the reference plane and the midpoints of the second set sides.

Abstract: A photomask substrate with a substantially uniform thickness comprises: a first surface, which is a continuous curved surface whereon a mask pattern is to be formed; and a second surface. The first surface exhibits a square shape that comprises an opposing pair of first set sides and an opposing pair of second set sides and has support parts at end parts along the first set sides. When the photomask substrate is held such that the first surface is in a substantially vertical state, a reference plane that is parallel to a tangential plane of the first surface at the center point of the first surface is defined on the photomask substrate side that is closer to the first surface than to the second surface. At this time, a first distance in the thickness direction between the reference plane and the center point of the first surface is shorter than second distances in the thickness direction between the reference plane and the midpoints of the second set sides.

Abstract: A method for manufacturing a glass substrate by a fusion process includes flowing fused glass into a fusion pipe, and gradually cooling and solidifying the fused glass by allowing the glass to flow downward from the fusion pipe. An asperity is formed on a surface of the glass substrate by fastening and pressing the glass toward a direction of thickness of the glass with a pair of transfer rollers while the glass is flowing down from the fusion pipe.

Abstract: A method for manufacturing a glass substrate by fusion process comprising the following steps; flowing fused glass into a fusion pipe, and gradually cooling and solidifying the fused glass by flowing downward from the fusion pipe, wherein forming an asperity on a surface of the glass substrate by fastening and pressing the glass toward a direction of thickness of the glass with a pair of transfer rollers during the glass is flowing down from the fusion pipe.