Fabricating large area multi-tier nanostructures
View Patent ↗Methods for fabricating and replicating self-aligned multi-tier nanoscale structures for a variety of cross-sectional geometries. These methods can utilize a single lithography step whereby the need for alignment and overlay in the process is completely eliminated thereby enabling near-zero overlay error. Furthermore, techniques are developed to use these methods to fabricate self-aligned nanoscale multi-level/multi-height patterns with various shapes for master templates, replica templates and nanoimprint based pattern replication. Furthermore, the templates can be used to pattern multiple levels in a sacrificial polymer resist and achieve pattern transfer of the levels into a variety of substrates to form completed large area nanoelectronic and nanophotonic devices using only one patterning step.
1. A method for pattern transfer of multi-tier structures using nanoimprint lithography, the method comprising:
nanoimprinting a multi-tier resist pattern using a multi-tier nanoimprint template, wherein said multi-tier resist pattern resides on a hard mask which resides on a substrate material;
removing a residual layer of said multi-tier resist pattern;
using said multi-tier resist pattern as an etch mask to etch said hard mask;
using said multi-tier resist pattern and said hard mask together as an etch mask for etching into said substrate material;
etching a lower level in said multi-tier resist pattern leaving behind a narrow single tier resist pattern;
using said single tier resist pattern as an etch mask to etch said hard mask;
using said single tier resist pattern and a remaining portion of said hard mask in combination as an etch mask to etch into said substrate material a further time; and
removing said single tier resist pattern and said remaining portion of said hard mask thereby forming a multi-tier replica structure in said substrate material.
2. The method as recited in claim 1 , wherein said substrate comprises a nanoimprint template material resulting in a nanoimprint replica template.
3. A method for forming multi-tier asymmetric nanostructures, the method comprising:
creating grating structures in a polymer resist forming a resist pattern on an underlying substrate;
transferring said resist pattern into said underlying substrate;
stripping said resist pattern;
evaporating a first metal at an angle to form an angled first metal mask on said grating structures;
etching said first metal to define a critical dimension of said first metal or performing an angled etch of said first metal at a direction opposite as said evaporation of said first metal;
etching said substrate to form a second level of grating features using said first metal as a mask; and
removing a remaining portion of said first metal to expose multi-tiered to expose multi-tiered asymmetric nanostructures.
4. The method as recited in claim 3 , wherein said first metal comprises chromium.
5. The method as recited in claim 3 further comprising:
depositing a second metal at a glancing angle on said multi-tiered asymmetric nanostructures on said substrate.
6. The method as recited in claim 5 , wherein said second metal comprises aluminum.
7. The method as recited in claim 5 , wherein said second metal is deposited by one of the following: electron beam evaporation and sputtering.
8. The method as recited in claim 3 , wherein said exposed multi-tiered asymmetric nanostructures is an asymmetric multi-tier nanoimprint template.
9. The method as recited in claim 8 further comprising:
creating asymmetric multi-tier structures in nanoimprint resist using said asymmetric multi-tier nanoimprint template and nanoimprint lithography; and
depositing a second metal at a glancing angle on said asymmetric multi-tier structures.
10. The method as recited in claim 9 , wherein said second metal comprises aluminum.
11. The method as recited in claim 9 , wherein said second metal is deposited by one of the following: electron beam evaporation and sputtering.
12. The method as recited in claim 3 , wherein said substrate comprises one of the following: polyimide, polycarbonate, polyethylene terephthalate and glass.