Reversal lithography approach by selective deposition of nanoparticles
A novel reversal lithography process without etch back is described. The reversal material comprises nanoparticles that are selectively deposited into the gaps between features without overcoating the tops of the features. As a result, a patterned imaging layer can be removed using solvent, blanket exposure followed by developer washing, or dry etching directly, without an etch-back process, and the original bright field lithography pattern can be reversed into dark field features, and transferred into subsequent layers using the nanoparticle reversal material as an etch mask.
1. A method of forming a microelectronic structure, said method comprising:
(a) providing a wafer stack, said stack comprising:
a substrate having a surface;
one or more intermediate layers optionally formed on the substrate surface; and
a patterned imaging layer on the intermediate layers, if present, or on the substrate surface if no intermediate layers are present, wherein said patterned imaging layer comprises a plurality of features, said features each being defined by sidewalls and a top surface;
(b) applying a pattern reversal composition to said patterned imaging layer to form a pattern reversal mask, wherein said pattern reversal composition is substantially non-polymeric, said composition comprising nanoparticles dispersed in a solvent system, wherein said nanoparticles are selectively deposited between said features during said applying and adjacent said sidewalls without overcoating said top surfaces;
(c) removing said patterned imaging layer to yield a reversed pattern comprising said mask; and
(d) transferring said reversed pattern into said intermediate layers, if present, or into said substrate if no intermediate layers are present.
2. The method of claim 1 , wherein said providing (a) comprises:
providing a substrate having a surface;
optionally forming one or more intermediate layers on said substrate surface;
applying a photosensitive composition to form an imaging layer on said intermediate layers, if present, or on said substrate surface if no intermediate layers are present; and
patterning said imaging layer to yield said patterned imaging layer.
3. The method of claim 2 , wherein said patterning comprises:
exposing said imaging layer to radiation to yield exposed portions of said imaging layer; and
contacting said imaging layer with a developer so as to remove said exposed portion.
4. The method of claim 1 , wherein said stack comprises one or more intermediate layers, said intermediate layers being selected from the group consisting of anti-reflective layers, spin-on carbon (SOC) layers, amorphous carbon layers, hardmask layers, planarization layers, and combinations thereof.
5. The method of claim 1 , wherein said features are selected from the group consisting of lines, spaces, pillars, trenches, holes, and combinations thereof.
6. The method of claim 1 , wherein said features have respective feature sizes ranging from about 5 nm to about 100 nm.
7. The method of claim 1 , wherein said applying (b) comprises spin coating said pattern reversal composition onto said patterned imaging layer.
8. The method of claim 1 , wherein said nanoparticles are selected from the group consisting of silica, alumina, Sb 2 O 5 , ZrO 2 , HfO 2 , TiO 2 , ZnO 2 , and mixtures thereof.
9. The method of claim 1 , wherein said nanoparticles have an average particle size of less than about 10 nm.
10. The method of claim 1 , wherein said nanoparticles comprise a metal oxide coating selected from the group consisting of alumina, Sb 2 O 5 , ZrO 2 , HfO 2 , TiO 2 , ZnO 2 .
11. The method of claim 1 , wherein said solvent system contains a solvent selected from the group consisting of water, propylene glycol methyl ether acetate, propylene glycol monomethyl ether, ethyl lactate, propylene glycol n-propyl ether, gamma-butyrolactone, cyclohexanone, and cyclopentanone, mesitylene, methyl iso-butyl carbinol (MIBC), and mixtures thereof.
12. The method of claim 1 , wherein said solvent system contains water and at least one co-solvent selected from the group consisting of propylene glycol methyl ether acetate, propylene glycol monomethyl ether, ethyl lactate, propylene glycol n-propyl ether, gamma-butyrolactone, cyclohexanone, and cyclopentanone, and mixtures thereof.
13. The method of claim 1 , wherein no etching occurs prior to removal of the imaging layer in (c).
14. The method of claim 1 , wherein said removing (c) comprises contacting the imaging layer with a solvent.
15. The method of claim 1 , wherein said removing (c) comprises etching said imaging layer.
16. The method of claim 1 , wherein said removing (c) comprises:
blanket exposing said imaging layer to radiation; and
contacting said blanket-exposed imaging layer with a developer so as to remove said imaging layer.
17. The method of claim 1 , wherein said reversed pattern comprises reversed features selected from the group consisting of trenches, holes, pillars, lines, spaces, and combinations thereof.
18. The method of claim 17 , wherein said reversed features have a feature size of from about 5 nm to about 100 nm.
19. The method of claim 1 , wherein said transferring (d) comprises etching said reversed pattern into said intermediate layers, if present, or into said substrate if no intermediate layers are present using said pattern reversal mask as an etch mask.
20. A method of forming a microelectronic structure, said method comprising:
(a) providing a wafer stack, said stack comprising:
a substrate having a surface;
one or more intermediate layers optionally formed on the substrate surface; and
a patterned imaging layer on the intermediate layers, if present, or on the substrate surface if no intermediate layers are present, wherein said patterned imaging layer comprises a plurality offeatures, said features each being defined by sidewalls and a top surface;
(b) applying a pattern reversal composition to said patterned imaging layer to form a pattern reversal mask, said composition comprising nanoparticles dispersed in a solvent system;
(c) without altering said pattern reversal mask, removing said patterned imaging layer to yield a reversed pattern comprising said mask; and
(d) transferring said reversed pattern into said intermediate layers, if present, or into said substrate if no intermediate layers are present.
21. A method of forming a microelectronic structure, said method comprising:
(a) providing a wafer stack, said stack comprising:
a substrate having a surface;
one or more intermediate layers optionally formed on the substrate surface; and
a patterned imaging layer on the intermediate layers, if present, or on the substrate surface if no intermediate layers are present, wherein said patterned imaging layer comprises a plurality of features, said features each being defined by sidewalls and a top surface;
(b) applying a pattern reversal composition to said patterned imaging layer to form a pattern reversal mask, said composition comprising nanoparticles dispersed in a solvent system, wherein said nanoparticles are selectively deposited between said features during said applying and adjacent said sidewalls without overcoating said top surfaces, and wherein said solvent system contains a solvent selected from the group consisting of water, propylene glycol methyl ether acetate, propylene glycol monomethyl ether, ethyl lactate, propylene glycol n-propyl ether, gamma-butyrolactone, cyclohexanone, and cyclopentanone, mesitylene, methyl iso-butyl carbinol (MTBC), and mixtures thereof;
(c) removing said patterned imaging layer to yield a reversed pattern comprising said mask; and
(d) transferring said reversed pattern into said intermediate layers, if present, or into said substrate if no intermediate layers are present.