A mask blank comprising a substrate, and having a first main surface and a second main surface, wherein:
- the substrate is made of a quartz glass containing TiO2 in an amount of 5 to 10 mass %,
- the second main surface is a main surface on the side where a layer for circuit pattern is disposed,
- the first main surface has a normal region having a square shape in which each side has a length L2 in an approximately central part of the first main surface,
- the normal region has a frame-shaped region which is a peripheral part of the normal region and an inner region surrounded by the frame-shaped region,
- the inner region has a square shape in which each side has a length L3 of 132 mm,
- the frame-shaped region includes an outer boundary having four sides which coincide with the sides of the square shape of the normal region and an inner boundary having four sides which coincide with the sides of the square shape of the inner region, the outer boundary having a shape that coincides with a shape formed by enlarging the inner boundary so that the sides of the inner frame are moved parallel outward by 8 mm each,
- when the vertexes of the outer boundary of the frame-shaped region are referred to respectively as vertexes A2, B2, C2, and D2 counterclockwise, the frame-shaped region includes first to fourth corner regions respectively in an each corner part of the frame-shaped region, the first corner region including the vertex A2, the second corner region including the vertex B2, the third corner region including the vertex C2, the fourth corner region including the vertex D2, and each corner region having a square shape in which each side has a length of 8 mm,
- the frame-shaped region has a first middle region having a square shape in which each side has a length of 8 mm in the middle position between the first corner region and the fourth corner region, a second middle region having a square shape in which each side has a length of 8 mm in the middle position between the first corner region and the second corner region, a third middle region having a square shape in which each side has a length of 8 mm in the middle position between the second corner region and the third corner region, and a fourth middle region having a square shape in which each side has a length of 8 mm in the middle position between the third corner region and the fourth corner region, and
- the following conditions (iv), (v), and (vi) are satisfied:
- (iv) the inner region has a flatness Fin1 of 200 nm or less, the flatness being determined on the basis of a least-squares plane of the normal region,
- (v) when one of the corner regions of the frame-shaped region is referred to as an n-th corner region and two middle regions nearest to the n-th corner region are respectively referred to as a first near middle region and a second near middle region, and
- when the maximum height and minimum height of the n-th corner region are expressed by Hmax(Cn) and Hmin(Cn), respectively, the maximum height and minimum height of the first near middle region are expressed by Hmax(Cn) and Hmin(Cn), respectively, and the maximum height and minimum height of the second near middle region are expressed by Hmax(Cn) and Hmin(Cn), respectively, the maximum heights and the minimum heights being determined on the basis of the least-squares plane of the normal region,
- a maximum height difference ΔD is 125 nm or less with respect to each of n=1 to 4,
- wherein the maximum height difference ΔD is represented by expression(1):
- ΔD=Max {Hmax(Cn)−Hmin(M1),Hmax(Cn)−Hmin(M2),Hmax(M1)−Hmin(Cn),Hmax(M2)−Hmin(Cn)} expression (1)
- wherein Max{x1, x2, x3, x4} means the maximum value among x1 to x4, and
- (vi) the frame-shaped region includes at least one whole contour line therein, and
- wherein a contour line present in the frame-shaped region has an approximately square shape in which a space between sides opposite to each other is 132 mm to 148 mm.