Abstract: A mask blank glass substrate having a maximum value of a circularly averaged power spectral density of 1,000 nm4 or less at a spatial frequency of 0.1 ?m?1 or more and 20 ?m?1 or less, the maximum value being obtained by measuring a surface morphology of a region of 10 ?m×10 ?m with an atomic force microscope.

Abstract: A substrate for mask blanks having first and second main surfaces of 152 mm×152 mm square and a thickness of 6.35 mm, wherein: when a range of 132 mm×132 mm square centered on an intersection of diagonal lines is defined as a calculation region in each of the first and second main surfaces, on a substrate surface of the calculation region of at least one of the first and second main surfaces, flatness of the substrate surface of the calculation region based on a least square plane is 100 nm or less, and a difference (PV) between a highest value and a lowest value of a height of a calculation surface represented by a difference between shapes of the substrate surfaces before and after smoothing processing with a Gaussian filter (10 mm×10 mm) based on the least square plane is 20 nm or less.

Abstract: Proposed herein is a method for producing a substrate suitable for mask blanks for EUVL and the method being capable of suppressing a concave defect having a depth of less than 5 nm. The present invention provides a method for producing a substrate in which final polishing is performed by a polishing apparatus having an upper polishing plate equipped with a polishing pad, the method comprising the steps of placing a substrate stock in the polishing apparatus so that the main surface of the substrate stock face toward the upper polishing plate; rotating the upper polishing plate and polishing the substrate stock concomitantly with a polishing slurry on the main surface of the substrate stock; and raising the upper polishing plate which is kept being rotated to separate it from the main surface of the polished substrate stock.

Abstract: A mask blank glass substrate having a maximum value of a circularly averaged power spectral density of 1,000 nm4 or less at a spatial frequency of 0.1 ?m?1 or more and 20 ?m?1 or less, the maximum value being obtained by measuring a surface morphology of a region of 10 ?m×10 ?m with an atomic force microscope.

Abstract: A mask blanks substrate having a flatness of a calculation surface of 100 nm or less when a calculation region passing through central portions of first and second main surfaces and extending in a horizontal direction is set, a first region surface is cut out, a second region surface is cut out by setting a reference plane and a rotation axis and rotating the substrate by 180°, least square planes are calculated, the first and second region surfaces are converted into height maps to positions on the least square planes, the height map of the to second region surface is set as a reverse height map by symmetrically moving the height map, and a map of a calculated height obtained by adding heights of the height map of the first region surface and the reverse height map of the second region surface is set as the calculation surface.

Abstract: A polishing composition including a colloidal silica containing colloidal silica particles, a pH adjusting agent, and a chelating agent provides a substrate that has a surface having a high flatness, low defects and a low surface roughness with low cost and high productivity, and a substrate having high surface quality suitable as a substrate for mask blanks such as a glass substrate containing SiO2 as a main component, particularly, as a substrate for mask blanks used in EUVL.

Abstract: A mask blank glass substrate having a maximum value of a circularly averaged power spectral density of 1,000 nm4 or less at a spatial frequency of 0.1 ?m?1 or more and 20 ?m?1 or less, the maximum value being obtained by measuring a surface morphology of a region of 10 ?m×10 ?m with an atomic force microscope.