Duty cycle, depth, and surface energy control in nano fabrication
Techniques for fabricating slanted surface-relief structures are disclosed. In some embodiments, a method for of fabricating a target slanted surface-relief structure, such as a nanoimprint lithography (NIL) mold or a slanted surface-relief grating, includes manufacturing a preliminary surface-relief structure that includes a plurality of ridges and modifying a parameter of the preliminary surface-relief structure to make the target slanted surface-relief structure. The parameter includes a width of each of the plurality of ridges, a height of each of the plurality of ridges, a surface energy of the preliminary surface-relief structure, or a slant angle of an edge of the plurality of ridges. Modifying the parameter includes depositing a material layer on the preliminary surface-relief structure and etching or surface-treating the material layer.
1. A method of fabricating a nanoimprint lithography (NIL) mold with a target surface-relief structure, the method comprising:
manufacturing a preliminary surface-relief structure of the NIL mold, the preliminary surface-relief structure comprising a plurality of ridges, wherein a parameter of the preliminary surface-relief structure is different from a corresponding parameter of the target surface-relief structure; and
modifying the parameter of the preliminary surface-relief structure to make the target surface-relief structure, wherein modifying the parameter of the preliminary surface-relief structure comprises:
depositing a material layer on the preliminary surface-relief structure using a vapor deposition process; and
etching or surface-treating the deposited material layer using a dry or wet isotropic etching process to make the target surface-relief structure, wherein the target surface-relief structure is different from the preliminary surface-relief structure in at least one of a height or a slant angle of a ridge in the plurality of ridges.
2. The method of claim 1 , wherein the NIL mold comprises a master NIL mold or a soft stamp for nanoimprint lithography.
3. The method of claim 1 , wherein the parameter of the preliminary surface-relief structure comprises a width of each of the plurality of ridges.
4. The method of claim 3 , wherein modifying the parameter of the preliminary surface-relief structure comprises:
depositing a spacer layer on the preliminary surface-relief structure; and
anisotropically etching the spacer layer to remove the spacer layer on top of the plurality of ridges and the spacer layer between the plurality of ridges, and to keep the spacer layer on sidewalls of the plurality of ridges.
5. The method of claim 4 , wherein the etching comprises plasma etching, ion beam etching, reactive ion beam etching, or chemical assisted reactive ion beam etching.
6. The method of claim 1 , wherein the parameter of the preliminary surface-relief structure comprises a surface energy of the preliminary surface-relief structure.
7. The method of claim 6 , wherein modifying the parameter of the preliminary surface-relief structure comprises:
depositing a spacer layer on the preliminary surface-relief structure, wherein the spacer layer has a surface energy different from the surface energy of the preliminary surface-relief structure; and
surface-treating the spacer layer.
8. The method of claim 7 , wherein surface-treating the spacer layer comprises:
treating a surface of the spacer layer using hexamethyldisilazane (HMDS) or fluorinated self-assembled monolayer (F SAM).
9. The method of claim 1 , wherein:
the plurality of ridges comprises slanted ridges; and
the parameter of the preliminary surface-relief structure comprises a slant angle of an edge of the slanted ridges.
10. The method of claim 9 , wherein modifying the parameter of the preliminary surface-relief structure comprises:
depositing a spacer layer on the preliminary surface-relief structure; and
etching the spacer layer at a slanted angle using a plasma or ion beam.
11. The method of claim 1 , wherein the preliminary surface-relief structure comprises a slanted surface-relief grating structure.
12. A method of fabricating a target nanoimprint lithography (NIL) mold, the method comprising:
manufacturing a preliminary NIL mold, the preliminary NIL mold comprising a substrate and a plurality of ridges on the substrate;
depositing a material layer on the preliminary NIL mold; and
etching the deposited material layer on the preliminary NIL mold at a slanted angle using a plasma or ion beam to achieve the target NIL mold, wherein the target NIL mold is different from the preliminary NIL mold in a slant angle of a ridge in the plurality of ridges.
13. The method of claim 12 , wherein the depositing and the etching modify at least one of:
a width of each of the plurality of ridges;
a height of each of the plurality of ridges;
a surface energy of the preliminary NIL mold; or
a slant angle of an edge of each of the plurality of ridges.
14. The method of claim 12 , wherein:
the plurality of ridges form a slanted surface-relief grating.