Substrate with film for reflective mask blank, reflective mask blank, and method for manufacturing reflective mask

A substrate with a film for a reflective mask blank comprising a substrate, a multilayer reflection film formed at the side of one main surface of the two main surfaces of the substrate, and configured to reflect EUV light, and a back surface conductive film formed in contact with the other main surface of the two main surfaces, wherein

• the back surface conductive film has a first composition at the side in contact with the substrate, and a different composition at the side remotest from the substrate,
• the first composition at the side in contact with the substrate i) consists of silicon and nitrogen, ii) comprises silicon, nitrogen, and either or both of oxygen and carbon, and has a total content of silicon and nitrogen of not less than 70 at %, iii) comprises silicon, nitrogen, and at least one element selected from the group consisting of tantalum, molybdenum, chromium, titanium, zirconium, niobium, hafnium and tungsten, and has a total content of silicon and nitrogen of not less than 70 at %, or iv) comprises silicon and nitrogen, at least one element selected from the group consisting of tantalum, molybdenum, chromium, titanium, zirconium, niobium, hafnium and tungsten, and either or both of oxygen and carbon, and has a total content of silicon and nitrogen of not less than 70 at %,
• the different composition at the side remotest from the substrate comprises tantalum, and at least one element selected from the group consisting of silicon, germanium and aluminum, and has a tantalum content of not less than 60 at % and a total content of nitrogen and oxygen of not more than 15 at %, and
• the back surface conductive film has a thickness of not more than 50 nm.