PHOTOMASK FOR EXTREME ULTRAVIOLET
An extreme ultraviolet photomask includes a conductive layer; a substrate disposed on the conductive layer; a multilayer, comprising different metals alternately stacked on the substrate; a protective layer disposed on the multilayer; a low-reflectance part disposed on a portion of the protective layer, wherein the low-reflectance part comprises a first absorbent layer disposed on the portion of the protective layer, a low-reflectance layer formed on the first absorbent layer, and a first intagliated part formed at the portion where the protective layer is exposed; and a high-reflectance part disposed on another portion of the protective layer, wherein the high-reflectance part comprises a second absorbent layer disposed on the other portion of the protective layer, a high-reflectance layer disposed on the second absorbent layer, and a second intagliated part formed at the other where the protective layer is exposed.
1 . A photomask for extreme ultraviolet comprising:
a conductive layer;
a substrate disposed on the conductive layer;
a multilayer, comprising different metals alternately stacked on the substrate;
a protective layer disposed on the multilayer;
a low-reflectance part disposed on a portion of the protective layer, wherein the low-reflectance part comprises a first absorbent layer disposed on the portion of the protective layer, a low-reflectance layer formed on the first absorbent layer, and a first intagliated part formed at the portion where the protective layer is exposed; and
a high-reflectance part disposed on another portion of the protective layer, wherein the high-reflectance part comprises a second absorbent layer disposed on the other portion of the protective layer, a high-reflectance layer disposed on the second absorbent layer, and a second intagliated part formed at the other where the protective layer is exposed.
2 . The photomask for extreme ultraviolet of claim 1 ,
wherein a first layer of the multilayer comprises molybdenum, and
a second layer of the multilayer comprises silicon or beryllium.
3 . The photomask for extreme ultraviolet of claim 2 ,
wherein the first layer has a thickness of 1 nm to 5 nm, and
the second layer has a thickness of 2 nm to 6 nm.
4 . The photomask for extreme ultraviolet of claim 1 ,
wherein the protective layer comprises one selected from the group consisting of ruthenium, ruthenium silicide, a chrome-based material, and combinations thereof.
5 . The photomask for extreme ultraviolet of claim 4 ,
wherein the protective layer has a thickness of 1 nm to 4 nm.
6 . The photomask for extreme ultraviolet of claim 1 ,
wherein the low-reflectance layer and the high-reflectance layer comprise a metal oxide,
wherein a laminate comprising the low-reflectance layer, the first absorbent layer and the protective layer has a reflectance of 3% to 8% for extreme ultraviolet with a wavelength of 13.5 nm, and
wherein another laminate comprising the high-reflectance layer, the second absorbent layer and the protective layer has a reflectance of 10% to 40% for extreme ultraviolet with the wavelength of 13.5 nm.
7 . The photomask for extreme ultraviolet of claim 6 ,
wherein the low-reflectance layer has a thickness of 12 nm to 30 nm, and the high-reflectance layer has a thickness of 4 nm to 10 nm.
8 . The photomask for extreme ultraviolet of claim 6 ,
wherein a thickness ratio of the thickness of the low-reflectance to the thickness of the high-reflectance layer has a value of 1.2 to 7.5.
9 . The photomask for extreme ultraviolet of claim 6 ,
wherein the metal oxide comprises one selected from the group consisting of silica, alumina, and combinations thereof.
10 . The photomask for extreme ultraviolet of claim 1 ,
wherein each of the first absorbent layer and the second absorbent layer comprises a lower absorbent layer formed on the protective layer, and an upper absorbent layer formed on the lower absorbent layer, and
wherein the lower absorbent layer comprises tantalum nitride, and the upper absorbent layer comprises molybdenum.
11 . The photomask for extreme ultraviolet of claim 10 ,
wherein the lower absorbent layer has a thickness of 1 nm to 5 nm, and
wherein the upper absorbent layer has a thickness of 20 nm to 40 nm.
12 . The photomask for extreme ultraviolet of claim 10 ,
wherein a thickness ratio of the thickness of the lower absorbent layer to the thickness of the upper absorbent layer has a value of 0.025 to 0.25.
13 . An extreme ultraviolet photomask comprising:
a substrate disposed on a conductive layer;
a multilayer, comprising a first layer of molybdenum, and a second layer of silicon or beryllium alternately stacked on the substrate;
a protective layer disposed on the multilayer;
a low-reflectance part disposed on a portion of the protective layer, wherein the low-reflectance part comprises a first absorbent layer disposed on the portion of the protective layer, a low-reflectance layer formed on the first absorbent layer, and a first intagliated part formed at the portion where the protective layer is exposed; and
a high-reflectance part disposed on another portion of the protective layer, wherein the high-reflectance part comprises a second absorbent layer disposed on the other portion of the protective layer, a high-reflectance layer disposed on the second absorbent layer, and a second intagliated part formed at the other where the protective layer is exposed.
14 . The extreme ultraviolet photomask of claim 13 , wherein the first and the second layers are alternately stacked to have a total number of layers between 40 to 200 layers.
15 . The extreme ultraviolet photomask of claim 13 , wherein the first and the second layers are alternately stacked to have a total of 50 to 160 layers.