EUV transmissive film
There is provided an EUV transmissive membrane having an EUV transmittance of 80.0% or more at a wavelength of 13.5 nm and including a main layer having an IR emissivity of 2.0% or more at a wavelength of 2 μm and a protective layer that covers at least one side of the main layer and has an IR transmittance of 70% or more at a wavelength of 2 μm.
1 . An extreme ultraviolet (EUV) transmissive membrane having an EUV transmittance of 80.0% or more at a wavelength of 13.5 nm, the EUV transmissive membrane comprising:
a main layer having an IR emissivity of 2.0% or more at a wavelength of 2 μm; and
a protective layer that covers at least one side of the main layer and has an IR transmittance of 70% or more at a wavelength of 2 μm;
wherein the main layer comprises at least one selected from the group consisting of Be and B 4 C as a main component;
wherein the main layer has a thickness of 10 to 70 nm;
wherein the protective layer has a thickness of 5 nm or less; and
wherein the protective layer is composed of at least one selected from the group consisting of calcium fluoride, silicon dioxide, and beryllium nitride.
2 . The EUV transmissive membrane according to claim 1 , wherein both sides of the main layer are covered with a pair of the protective layer.
3 . The EUV transmissive membrane according to claim 1 , wherein the main layer comprises an additive.
4 . The EUV transmissive membrane according to claim 3 , wherein a constituent element of the additive has an electronegativity that is 0.3 or higher or 0.3 or lower than the electronegativity of a major constituent element of the main layer.
5 . The EUV transmissive membrane according to claim 3 , wherein the additive comprises at least one element selected from the group consisting of Rb, Sr, Y, Nb, Mo, Si, K, Ca, B, and C.
6 . The EUV transmissive membrane according to claim 3 , wherein the main layer comprises Be as a main component, and the content of the additive is 5 to 40 at % with respect to the content of Be in the main layer.