Nanoimprint lithography process and patterned substrate obtainable therefrom
The present invention pertains to the field of nanoimprint lithography (NIL) processes and more specifically to a soft NIL process used for providing a sol-gel patterned layer on a substrate. Specifically, this process comprises a step of adjusting the solvent uptake of the sol-gel film to 10 to 50% vol., preferably between 15 and 40% vol., by varying the relative pressure of the solvent while a soft mould is applied onto the substrate coated with the sol-gel film.
1. A nanoimprint lithography (NIL) process, comprising the successive steps of:
a) preparing a solution of sol-gel metal or metalloid oxide precursor(s),
o) performing a calibration step to determine solvent relative pressure that should be applied during replication step d,
b) applying said solution onto a substrate to form a film,
c) equilibrating the film with the atmosphere under adjusted solvent vapor pressure, to obtain a gel film,
d) applying a soft mould onto said gel film to provide an assembly such that said gel film fills up the cavities of the mould, and maintaining said assembly under solvent vapor,
e) thermally treating said assembly so as to rigidify the gel film thus obtained,
f) removing the mould to obtain a substrate coated with a patterned gel, and
g) curing said patterned gel so as to obtain a patterned metal or metalloid oxide material on said substrate,
wherein the solvent uptake of the film is adjusted to 10 to 50% volume by varying the vapor pressure in a volatile solvent at the vicinity of the film and gel film during steps c) and d) and wherein the gel film does not comprise organic polymers.
2. The process according to claim 1 , wherein the thermal treatment is performed at a temperature of from 25 to 200° C.
3. The process according to claim 1 , wherein the curing step is performed at a temperature of from 200 to 800° C.
4. The process of claim 1 , wherein the solvent uptake of the film is adjusted between 15 and 40% vol.
5. The process of claim 1 , wherein the step of applying said solution onto a substrate to form a film is performed at a relative humidity of 20%.
6. The process of claim 1 , wherein the solvent is selected from the group consisting of water, ethanol, isopropanol, acetone, THF, hexane, toluene and their mixtures.
7. The process of claim 6 , wherein the solvent is water.
8. The process according to claim 1 , wherein the metal or metalloid oxide precursors are selected from the group consisting of inorganic salts, organics salts or alkoxides of at least one metal or metalloid or of a combination of at least one metal with at least one metalloid.
9. The process according to claim 8 , wherein that the metal or metalloid oxides obtained from the metal or metalloid oxide precursors are selected from the group consisting of TiO 2 , ZnO:TiO 2 , AlO (OH), V 2 O 5 , VO 2 , silicon oxides and Y-ZrO 2.
10. The process according to claim 1 , wherein the mould is manufactured from silicone elastomers, fluorinated polymers, polyvinylpyrrolidone (PVP), polylactic acid (PLA) or polyetherimide (PEI).
11. The process of claim 10 , wherein the mould is manufactured from silicone elastomers.
12. A patterned substrate obtainable by the process according to claim 1 .
13. A device for optical, photonic, electrical or biological applications comprising a patterned substrate according to claim 12 .
14. A nanoimprint lithography (NIL) process, comprising the successive steps of:
a) preparing a solution of sol-gel metal or metalloid oxide precursor(s),
o) performing a calibration step to determine the solvent relative pressure that should be applied during replication step d,
a′) converting the metal or the metalloid oxide precursors into the metal or the metalloid oxide suspension,
b) applying said solution onto a substrate to form a film,
c) equilibrating the film with the atmosphere under adjusted solvent vapor pressure, to obtain a gel film,
d) applying a soft mould onto said gel film to provide an assembly such that said gel film fills up the cavities of the mould, and maintaining said assembly under solvent vapor,
e) thermally treating said assembly so as to rigidify the gel film thus obtained, and
f) removing the mould to obtain a substrate coated with a patterned gel, wherein the solvent uptake of the film is adjusted to 10 to 50% volume by varying the vapor pressure in a volatile solvent at the vicinity of the film and gel film during steps c) and d), and wherein the gel film does not comprise organic polymers.
15. The process of claim 14 , further comprising, after step f), a step g) of curing said patterned gel so as to obtain a patterned metal or metalloid oxide material on said substrate.