Imprint lithography method and imprintable medium
An imprint lithography method is disclosed for reducing a difference between an intended topography and an actual topography arising from a part of a patterned layer of fixed imprintable medium. The method involves imprinting an imprint lithography template into a layer of flowable imprintable medium to form a patterned layer in the imprintable medium, and fixing the imprintable medium to form a patterned layer of fixed imprintable medium. Local excitation is applied to the part of the patterned layer to adjust a chemical reaction in the part of the patterned layer to reduce the difference between the intended topography and the actual topography arising from the part of the fixed patterned layer of imprintable medium when this is subsequently used as a resist for patterning the substrate. An imprint medium suitable for imprint lithography with the method is also disclosed.
1. An imprint lithography method for reducing a difference between an intended topography and an actual topography arising from a part of a patterned layer of fixed imprintable medium, the method comprising:
imprinting an imprint lithography template into a layer of flowable imprintable medium to form a patterned layer in the imprintable medium;
fixing the imprintable medium to form a patterned layer of fixed imprintable medium; and
separate from fixing the imprintable medium, applying local excitation to the part of the patterned layer having a topography by contact from the imprint lithography template to adjust a chemical reaction in the part of the patterned layer to reduce the difference between the intended topography and the actual topography arising from the part of the fixed patterned layer of imprintable medium.
2. The imprint lithography method of claim 1 , wherein the imprintable medium is fixed by curing with a first actinic radiation.
3. The imprint lithography method of claim 2 , wherein the fixing by curing with first actinic radiation comprises a polymerization reaction of a first monomer of the imprintable medium.
4. The imprint lithography method of claim 3 , wherein the chemical reaction comprises a polymerization reaction of a second monomer of the imprintable medium.
5. The imprint lithography method of claim 4 , wherein second monomer remaining unpolymerized after the polymerization reaction is removed by leaching from the fixed imprintable medium using a solvent leach.
6. The imprint lithography method of claim 1 , wherein the local excitation comprises local application to the part of the patterned layer of a selected dose of actinic radiation.
7. The imprint lithography method of claim 2 , wherein the local excitation comprises local application to the part of the patterned layer of a selected dose of second actinic radiation.
8. The imprint lithography method of claim 1 , wherein the local excitation is applied after fixing the imprintable medium to form a patterned layer of fixed imprintable medium.
9. The imprint lithography method of claim 8 , wherein the local excitation is applied after removal of the imprint lithography template from the patterned layer of fixed imprintable medium.
10. The imprint lithography method of claim 1 , wherein a mask is used to control local application of the local excitation.
11. The imprint lithography method of claim 1 , wherein the local excitation comprises or consists of local heating of the part of the patterned layer.
12. The imprint lithography method of claim 11 , wherein the local heating is provided by a beam of radiation.
13. The imprint lithography method of claim 12 , wherein the local heating is provided by intersecting two or more beams of radiation at a point adjacent to the part of the patterned layer.
14. The imprint lithography method of claim 1 , wherein the chemical reaction comprises a chemical reaction of a reacting compound, leading to depletion of the reacting compound in the part of the patterned layer so that diffusion of the reacting compound into the part of the patterned layer is induced.
15. The imprint lithography method of claim 14 , wherein the reacting compound comprises a compound resistant to etching.
16. The imprint lithography method of claim 1 , wherein the actual topography arising from the part of the patterned layer of fixed imprintable medium is determined by measuring a topography of the part of the patterned layer of fixed imprintable medium.
17. The imprint lithography method of claim 1 , wherein the fixed imprintable medium is maintained at a temperature within 20°C. of the glass transition temperature of the imprintable medium, while the chemical reaction takes place.
18. An imprint medium for imprint lithography comprising first and second monomers, wherein the imprint medium is curable by a polymerization reaction of the first monomer induced by a first excitation leaving the second monomer substantially unpolymerized, and wherein the second monomer is polymerizable by a second excitation, wherein the first monomer is substantially polymerizable by the first excitation comprising irradiation with a first dose of first actinic radiation and wherein the second monomer is substantially polymerizable by the second excitation comprising irradiation with a second dose of the essentially same first actinic radiation.
19. An imprint lithography method for reducing a difference between an intended topography and an actual topography arising from a part of a patterned layer of fixed imprintable medium, the method comprising:
imprinting an imprint lithography template into a layer of flowable imprintable medium to form a patterned layer in the imprintable medium, the imprintable medium comprising a first monomer and a second monomer;
fixing the imprintable medium to form a patterned layer of fixed imprintable medium; and
applying local excitation to the part of the patterned layer to adjust a chemical reaction in the part of the patterned layer to reduce the difference between the intended topography and the actual topography arising from the part of the fixed patterned layer of imprintable medium, wherein the chemical reaction comprises a polymerization reaction of a second monomer of the imprintable medium.
20. An imprint lithography method for reducing a difference between an intended topography and an actual topography arising from a part of a patterned layer of fixed imprintable medium, the method comprising:
imprinting an imprint lithography template into a layer of flowable imprintable medium to form a patterned layer in the imprintable medium;
fixing the imprintable medium to form a patterned layer of fixed imprintable medium by application of a first actinic radiation; and
applying local excitation to the part of the patterned layer to adjust a chemical reaction in the part of the patterned layer to reduce the difference between the intended topography and the actual topography arising from the part of the fixed patterned layer of imprintable medium, wherein the local excitation comprises local application to the part of the patterned layer of a selected dose of second actinic radiation.