Mask blank substrate, substrate with multilayer reflection film, transmissive mask blank, reflective mask blank, transmissive mask, reflective mask, and semiconductor device fabrication method

Disclosed is a mask blank substrate for use in lithography, wherein a main surface of the substrate satisfies a relational equation of (BA70−BA30)/(BD70−BD30) 350 (%/nm), and has a maximum height (Rmax) 1.2 nm in a relation between a bearing area (%) and a bearing depth (nm) obtained by measuring, with an atomic force microscope, an area of 1 μm×1 μm in the main surface on the side of the substrate where a transfer pattern is formed, wherein BA30 is defined as a bearing area of 30%, BA70 is defined as a bearing area of 70%, and BD70 and BD30 are defined to respectively represent bearing depths for the bearing area of 30% and the bearing area of 70%.