Reflective film coated substrate, mask blank, reflective mask, and semiconductor device manufacturing method

A mask blank comprising:

• a substrate having:
• two main surfaces opposite from each other, and
• end faces connected to outer edges of the two main surfaces;
• a reflective film formed on one of the main surfaces as a multilayer structure comprising low refractive index layers and high refractive index layers alternately formed;
• and
• a pattern-forming thin film formed on the reflective film,
• wherein a content (atomic %) of a first element in the low refractive index layers is higher than a content (atomic %) of any other element in the low refractive index layers, and a content (atomic %) of a second element in the high refractive index layers is higher than a content (atomic %) of any other element in the high refractive index layers, the second element being a different element from the first element, and
• wherein the reflective film extends onto at least part of the end faces as a film without an interface between the low refractive index layer and the high refractive index layer, or as a film that is formed by mixing the first element and the second element.

A reflective mask comprising:

• a substrate having:
• two main surfaces opposite to each other, and
• end faces connected to outer edges of the two main surfaces;
• a reflective film formed on one of the main surfaces as a multilayer structure comprising low refractive index layers and high refractive index layers alternately formed;
• and
• a thin film formed on the reflective film and having a transfer pattern;
• wherein a content (atomic %) of a first element in the low refractive index layers is higher than a content (atomic %) of any other element in the low refractive index layers, and a content (atomic %) of a second element in the high refractive index layers is higher than a content (atomic %) of any other element in the high refractive index layers, the second element being a different element from the first element, and
• wherein the reflective film extends onto at least part of the end faces as a film without an interface between the low refractive index layer and the high refractive index layer, or as a film that is formed by mixing the first element and the second element.