Fabricating large area multi-tier nanostructures
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 fabricating self-aligned nanoscale multi-tier templates, the method comprising:
sputtering a layer of an etch stop onto a wafer;
depositing a layer of a template material onto said layer of said etch stop;
patterning a resist on said template material;
performing a first level etch of said template material using said resist as a mask;
removing said resist followed by depositing spacer material on said template material;
anisotropic etching of said spacer material to define side walls spacers;
performing a second level etching of said template material using said side wall spacers as a mask until reaching said etch stop; and
removing said side wall spacers to reveal self-aligned multi-tier features in said template material.
2. The method as recited in claim 1 , wherein said template material comprises silicon dioxide, wherein said spacer material comprises titanium nitride, wherein said etch stop comprises indium tin oxide.
3. The method as recited in claim 1 , wherein said template material comprises silicon, wherein said spacer material comprises silicon dioxide, wherein said etch stop comprises silicon dioxide.
4. The method as recited in claim 1 , wherein said resist is patterned on said template material using one of the following: nanoimprint lithography, electron beam lithography and photolithography.
5. The method as recited in claim 1 , wherein said self-aligned multi-tiered features correspond to a master template.
6. The method as recited in claim 1 , wherein said self-aligned multi-tiered features comprise one of the following: a multi-tiered grating, a multi-tiered trench, a multi-tiered cylinder, a multi-tiered hole, a tube structure, a shaped multi-tiered pillar, a shaped multi-tiered hole, and a shaped tubed structure.
7. The method as recited in claim 6 , wherein said shaped multi-tiered pillar, said shaped multi-tiered hole and said shaped tubed structure have cross sections of one of the following: elliptical, triangular, quadrilateral, diamond, polygonal, star shaped and serpentine.