Patent ID: 11899356
Assignee: HOYA CORPORATION
Field: Optics (Instruments)
Classification: CPC G | IPC G

Claim 6:
7. 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.