Damascene template for directed assembly and transfer of nanoelements
Damascene templates have two-dimensionally patterned raised metal features disposed on an underlying conductive layer extending across a substrate. The templates are topographically flat overall, and the patterned conductive features establish micron-scale and nanometer-scale patterns for the assembly of nanoelements into nanoscale circuits and sensors. The templates are made using microfabrication techniques together with chemical mechanical polishing. These templates are compatible with various directed assembly techniques, including electrophoresis, and offer essentially 100% efficient assembly and transfer of nanoelements in a continuous operation cycle. The templates can be repeatedly used for transfer of patterned nanoelements thousands of times with minimal or no damage, and the transfer process involves no intermediate processes between cycles. The assembly and transfer processes employed are carried out at room temperature and pressure and are thus amenable to low cost, high-rate device production.
1. A damascene template for the electrophoretic assembly and transfer of patterned nanoelements, the template comprising:
a substantially planar substrate;
a first insulating layer disposed on a surface of the substrate;
an adhesion layer disposed on a surface of the first insulating layer opposite the substrate;
a conductive metal layer disposed on a surface of the adhesion layer opposite the first insulating layer;
a second insulating layer disposed on a surface of the conductive metal layer opposite the adhesion layer; and
a hydrophobic coating selectively disposed on exposed surfaces of the second insulating layer opposite the conductive metal layer;
wherein the conductive metal layer is continuous across at least one region of the substrate, and within said region the conductive metal layer has a two-dimensional microscale or nanoscale pattern of raised features that interrupt the second insulating layer; wherein the second insulating layer substantially fills the spaces between said raised features; and wherein exposed surfaces of the raised features and the exposed surfaces of the second insulating layer are essentially coplanar.
2. The damascene template of claim 1 , wherein the substrate comprises silicon or a polymer.
3. The damascene template of claim 1 , wherein the substrate thickness is from 1 μm to 10 μm.
4. The damascene template of claim 1 , wherein first insulating layer comprises silicon dioxide, SiN 4 , or a polymer.
5. The damascene template of claim 1 , wherein first insulating layer thickness is from 5 to 500 nm.
6. The damascene template of claim 1 , wherein the adhesion layer comprises a material selected from the group consisting of chromium, titanium, titanium dioxide, titanium nitride, tantalum, tantalum nitride, tungsten, and combinations thereof.
7. The damascene template of claim 1 , wherein the adhesion layer thickness is from 3 nm to 50 nm.
8. The damascene template of claim 1 , wherein the conductive metal layer comprises gold, silver, tungsten, aluminum, titanium, ruthenium, copper, or a combination thereof.
9. The damascene template of claim 1 , wherein the second insulating layer comprises a material selected from the group consisting of SiO 2 , SiN 4 , Al 2 O 3 , an organic polymer, and combinations thereof.
10. The damascene template of claim 1 , wherein the second insulating layer has a thickness from 10 nm to 10 μm.
11. The damascene template of claim 1 , wherein the conductive metal layer comprises a planar portion having a thickness from 50 nm to 100 μm.
12. The damascene template of claim 1 , wherein the hydrophobic coating is a silane coating.
13. The damascene template of claim 1 , wherein the hydrophobic coating comprises a monolayer of alkyl silane molecules.
14. The damascene template of claim 1 , wherein the hydrophobic coating comprises octadecyltrichlorosilane.
15. The damascene template of claim 1 , wherein the contact angle of the hydrophobic coating is from 90 to 110°.
16. The damascene template of claim 1 , wherein the contact angle of the hydrophobic coating is about 100°.
17. The damascene template of claim 1 , wherein the contact angle of the exposed raised feature surfaces is from 15 to 21°.
18. The damascene template of claim 1 , wherein the contact angle of the exposed raised feature surfaces is about 18°.
19. The damascene template of claim 1 , wherein the height of the raised features is essentially the same as the thickness of the second insulating layer.
20. The damascene template of claim 1 , wherein the raised features comprise substantially linear features.
21. The damascene template of claim 20 , wherein the linear features are straight, curved, intersecting, or form a circle, triangle, or rectangle.
22. The damascene template of claim 1 , wherein the raised features are from 10 nm to 100 μm in width.
23. The damascene template of claim 1 , wherein the raised features are from 10 nm to 10 cm in length.
24. The damascene template of claim 1 , wherein the raised features in said region are in electrical contact with one another through the conductive metal layer.
25. The damascene template of claim 1 , wherein the exposed surfaces of raised features are essentially devoid of the hydrophobic coating.
26. The damascene template of claim 1 , wherein the template is flexible.
27. The damascene template of claim 1 , further comprising a plurality of nanoelements non-convalently attached to exposed surfaces of the raised features, wherein the exposed surfaces of the second insulating layer are essentially devoid of attached nanoelements.
28. The damascene template of claim 27 , wherein the nanoelements are nanoparticles, single-walled carbon nanotubes, multi-walled carbon nanotubes, nanowires, nanofibers, pentacene molecules, fullerene molecules, or polymers.
29. The damascene template of claim 27 , wherein the nanoelements are conducting, semi-conducting, or insulating.