Mask structures and methods of manufacturing
A lithography mask structure is provided, including: a substrate; at least one reflective layer over the substrate; and an absorber film stack over the at least one reflective layer, the absorber film stack including a plurality of first film layers of a first material and at least one second film layer of a second material. The second material is different from the first material, and the second film layer(s) is interleaved with the plurality of first film layers. In one embodiment, the total thickness of the absorber film stack is less than 50 nm. In another embodiment, the reflectivity of the absorber film stack is less than 2% for a pre-defined wavelength of EUV light. In a further embodiment, the second film layer(s) prevents the average crystallite size of the first film layers from exceeding the thickness of the first film layers.
1. A structure comprising:
a lithography mask comprising:
a substrate;
at least one reflective layer over the substrate; and
an absorber film stack over the at least one reflective layer, the absorber film stack comprising a plurality of first film layers and at least one second film layer, the first film layers comprising a first material and the at least one second film layer comprising a second material, the second material being different from the first material, wherein the at least one second film layer is interleaved with first film layers of the plurality of first film layers.
2. The structure of claim 1 , wherein the absorber film stack has a thickness T s , where T s is less than 50 nm.
3. The structure of claim 1 , wherein the absorber film stack has a reflectivity value R, where R is less than 2% for a pre-defined extreme ultraviolet wavelength of light to be incident on the lithography mask.
4. The structure of claim 1 , wherein one first film layer of the plurality of first film layers and one second film layer of the at least one second film layer have a combined thickness T c , wherein thickness T c is approximately equal to one-half of a pre-defined wavelength of extreme ultraviolet light to be incident on the lithography mask.
5. The structure of claim 1 , wherein one first film layer of the plurality of first film layers comprises an average crystallite size C f and a thickness T f , and wherein the at least one second material film layer interleaved with the first film layers is selected and positioned to prevent the average crystallite size C f from exceeding thickness T f .
6. The structure of claim 1 , wherein the first material has an absorption coefficient k, where k is greater than about 0.04 for a pre-defined wavelength of EUV light to be incident on the lithography mask.
7. The structure of claim 1 , wherein the first material comprises one or more metals, metal nitrides, or metal oxides which can be selectively removed from over the at least one reflective layer.
8. The structure of claim 7 , wherein the first material comprises at least one of nickel, cobalt, platinum, palladium, or a respective oxide or nitride thereof.
9. The structure of claim 7 , wherein the first material comprises a binary metal alloy or a respective oxide or nitride thereof.
10. The structure of claim 7 , wherein the first material comprises a ternary metal alloy or a respective oxide or nitride thereof.
11. The structure of claim 7 , wherein the thickness T f of one first film layer of the plurality of first film layers is between about 3.0 nm and 7.0 nm.
12. The structure of claim 1 , wherein the second material comprises a metal nitride, a metal oxide, or a combination thereof.
13. The structure of claim 12 , wherein one second film layer of the at least one second film layer has a thickness T s , where T s is between about 2.0 nm and 6.0 nm.
14. The structure of claim 1 , wherein the absorber film stack comprises an absorber film stress, the absorber film stress being less than about 200 MPa.
15. The structure of claim 1 , wherein the absorber film stack comprises a plurality of second film layers, the at least one second film layer being at least one second film layer of the plurality of second film layers.
16. The structure of claim 15 , wherein the first material comprises NiPt and the second material comprises TiN, and wherein at least one first film layer of the plurality of first film layers has a thickness T f of about 4.7 nm and at least one second film layer of the plurality of second film layers has a thickness T s of about 2.0 nm.
17. The structure of claim 1 , wherein the absorber film stack further comprises a deep-ultraviolet anti-reflective coating over the plurality of first film layers and the at least one second film layer.
18. A method comprising:
forming a lithography mask structure, the forming comprising:
obtaining a substrate;
forming at least one reflective layer over the substrate;
providing an absorber film stack over the at least one reflective layer, the providing comprising forming a plurality of first film layers and at least one second film layer interleaved in the absorber film stack, the plurality of first film layers comprising a first material, and the at least one second film layer comprising a second material, the second material being different from the first material; and
selectively removing at least a portion of the absorber film stack from over the at least one reflective layer.
19. The method of claim 18 , wherein one first film layer of the plurality of first film layers comprises an average crystallite size C f and a thickness T f , and wherein interleaving the at least one second film layer with the plurality of first film layers prevents contact between the one first film layer and an adjacent first film layer of the plurality of first film layers to prevent the average crystallite size C fm from exceeding the thickness T fm .
20. The method of claim 18 , wherein the first material comprises at least one of nickel, cobalt, platinum, or palladium, and the second material comprises a metal nitride, a metal oxide, or a combination thereof.