EUV transmissive membrane
Provided is an EUV transmissive membrane including a main layer composed of metallic beryllium and a protective layer composed of beryllium nitride that covers at least one side of the main layer.
1 . An EUV transmissive membrane comprising:
a main layer composed of metallic beryllium having a thickness of 10 to 70 nm; and
a protective layer composed of beryllium nitride that covers at least one side of the main layer having a thickness of 5 nm or less.
2 . The EUV transmissive membrane according to claim 1 , wherein both sides of the main layer are covered with the protective layer.
3 . The EUV transmissive membrane according to claim 1 , wherein the protective layer has a thickness of 1 nm to 5 nm.
4 . The EUV transmissive membrane according to claim 1 , wherein the protective layer has a thickness of 3 nm or less.
5 . The EUV transmissive membrane according to claim 1 , wherein the protective layer has a nitrogen concentration gradient region where nitrogen concentration decreases towards the main layer.
6 . The EUV transmissive membrane according to claim 5 , wherein the thickness of the nitrogen concentration gradient region is smaller than that of the protective layer.
7 . The EUV transmissive membrane according to claim 1 , wherein the main layer has a thickness of 15 to 50 nm.