Crosslinkable graft polymer non-preferentially wetted by polystyrene and polyethylene oxide

• US 8,445,592 B2
• Filed: 12/13/2011
• Issued: 05/21/2013
• Est. Priority Date: 06/19/2007
• Status: Active Grant

• Current Assignee: Micron Technology, Inc.
• Original Assignee: Micron Technology, Inc.
• Inventors: Millward, Dan B.
• Primary Examiner(s): JONES JR., ROBERT STOCKTON
• Application Number:
  US13/324,216
• Publication Number:
  US 20120082822A1
• Time in Patent Office: 525 Days
• Field of Search: 525/404, 525/108, 525/187, 528/393, 528/421
• US Class Current: 525/187
• CPC Class Codes: B32B 3/10 characterised by a discontinuous layer, i.e. formed of separate pieces of material
• CPC Class Codes: B81C 1/00031 Regular or irregular arrays of nanoscale structures, e.g. etch mask layer photomechanical, e.g. photolithographic, production of textured or patterned surfaces G03F7/00; lithographic processes for making patterned surfaces using printing and stamping G03F7/0002
• CPC Class Codes: B81C 2201/0149 Forming nanoscale microstructures using auto-arranging or self-assembling material
• CPC Class Codes: B81C 2201/0198 for making a masking layer
• CPC Class Codes: B82Y 30/00 Nanotechnology for materials or surface science, e.g. nanocomposites
• CPC Class Codes: C08G 81/02 at least one of the polymers being obtained by reactions involving only carbon-to-carbon unsaturated bonds
• CPC Class Codes: G03F 7/12 Production of screen printing forms or similar printing forms, e.g. stencils
• CPC Class Codes: G03F 7/40 Treatment after imagewise removal, e.g. baking
• CPC Class Codes: Y10T 428/24174 including sheet or component perpendicular to plane of web or sheet
• CPC Class Codes: Y10T 428/24182 Inward from edge of web or sheet
• CPC Class Codes: Y10T 428/24521 with component conforming to contour of nonplanar surface
• CPC Class Codes: Y10T 428/24612 Composite web or sheet

Abstract

Methods for fabricating a random graft PS-r-PEO copolymer and its use as a neutral wetting layer in the fabrication of sublithographic, nanoscale arrays of elements including openings and linear microchannels utilizing self-assembling block copolymers, and films and devices formed from these methods are provided. In some embodiments, the films can be used as a template or mask to etch openings in an underlying material layer.

Claims

1. A method of etching a substrate, comprising:

preparing a solution comprising an azido-functionalized random graft copolymer by;

reacting a reaction mixture comprising p-chloromethylstyrene monomers to form a p-chloromethylstyrene homopolymer comprising chloromethyl moieties and repeating units derived from p-chloromethylstyrene;

reacting the p-chloromethylstyrene homopolymer with one or more oligomers or polymers of poly(ethylene oxide) to form a graft copolymer comprising chloromethyl moieties, wherein the poly(ethylene oxide) has only one nucleophilic end; and

reacting the graft copolymer comprising chloromethyl moieties with an azide compound to displace chlorine atoms of the chloromethyl moieties to form azidomethyl moieties on the graft copolymer, wherein the azide compound is selected from the group consisting of sodium azide and R(N₃)_x, where R is a metal atom other than sodium, hydrogen or ammonium, and x is greater than zero;

applying the solution comprising the azido-functionalized random graft copolymer to a floor of a trench within a substrate, the trench having sidewalls, a width, and a length;

crosslinking the azido-functionalized random graft copolymer;

forming a polymer material comprising a poly(styrene-b-ethylene oxide) block copolymer within the trench;

annealing the polymer material to form a material comprising self-assembled polymer domains registered to the sidewalls and extending the length of the trench;

selectively removing a first polymer domain to form an etch mask comprising an array of openings separated by a second polymer domain; and

etching the substrate through the openings of the etch mask.

2. The method of claim 1, wherein the trench floor bears one or more strips of the azido-functionalized random graft copolymer oriented perpendicular to the trench sidewalls and adjacent to a strip of the exposed substrate, and the polymer material comprises a cylindrical-phase block copolymer.

3. The method of claim 1, further comprising crosslinking the polymer domains of the annealed polymer material.

4. The method of claim 1, wherein the sidewalls are preferentially wetting to one block of the polystyrene-b-ethylene oxide) block copolymer.

5. The method of claim 1, wherein the polymer domains of the annealed polymer material are oriented perpendicular to the trench floor.

6. The method of claim 5, wherein the poly(styrene-b-ethylene oxide) block copolymer is a lamellar-phase block copolymer.

7. The method of claim 5, wherein the poly(styrene-b-ethylene oxide) block copolymer is a cylindrical-phase block copolymer.

8. The method of claim 1, wherein the polymer material within the trench has a thickness of about an L_o value of the polystyrene-b-ethylene oxide) block copolymer.

9. The method of claim 1, wherein the polymer domains of the annealed polymer material extend from and interface with air and the substrate at the trench floor.

10. The method of claim 9, wherein the annealed polymer material comprises perpendicularly oriented, alternating lamellar polymer domains.

11. The method of claim 9, wherein the annealed polymer material comprises perpendicularly oriented cylinders.

12. The method of claim 11, wherein the perpendicularly oriented cylinders extend in a single row for the length of the trench.

13. The method of claim 11, wherein the perpendicularly oriented cylinders are in a hexagonal array.

14. The method of claim 1, wherein the etch mask comprises linear openings exposing the trench floor, the linear openings separated by perpendicularly oriented lamellar polymer domains at a pitch distance of about L_o extending parallel to the sidewalls for the length of the trench.

15. The method of claim 14, wherein the linear openings are about 5-60 nm wide.

16. The method of claim 1, wherein the etch mask comprises perpendicularly oriented cylindrical openings within a polymer matrix exposing the trench floor, the perpendicularly oriented cylindrical openings spaced apart at a pitch distance of about L_o.

17. The method of claim 1, wherein the etch mask comprises perpendicularly oriented cylinders extending from the trench floor at a pitch distance of about L_o, the trench floor exposed between the perpendicularly oriented cylinders.

18. The method of claim 1, further comprising, after crosslinking the azido-functionalized random graft copolymer,

masking one or more portions of the crosslinked azido-functionalized random graft copolymer;

and

removing exposed portions of the crosslinked azido-functionalized random graft copolymer to expose the substrate on the trench floor.

19. A method of etching a substrate, comprising:

preparing a solution comprising an azido-functionalized random graft copolymer by;

reacting a mixture comprising p-chloromethylstyrene and styrene to form polymer chains comprising chloromethyl moieties and repeating units derived from p-chloromethylstyrene and styrene, wherein the mixture comprises p-chloromethylstyrene in a molecular amount greater than a molecular amount of styrene;

reacting the polymer chains with one or more oligomers or polymers of poly(ethylene oxide) to form a graft copolymer comprising chloromethyl moieties, wherein the poly(ethylene oxide) has only one nucleophilic end; and

reacting the graft copolymer comprising chloromethyl moieties with an azide compound to displace chlorine atoms of the chloromethyl moieties to form azidomethyl moieties on the graft copolymer;

applying the solution comprising the azido-functionalized random graft copolymer to a floor of a trench within a substrate, the trench having sidewalls, a width and a length;

crosslinking the azido-functionalized random graft copolymer;

forming a polymer material comprising poly(styrene-b-ethylene oxide) block copolymer within the trench;

annealing the polymer material to form a material comprising self-assembled polymer domains;

selectively removing a first polymer domain to form an etch mask comprising openings; and

etching the substrate through the openings of the etch mask.

20. The method of claim 19, further comprising:

prior to crosslinking the azido-functionalized random graft copolymer, masking one or more portions of the azido-functionalized random graft copolymer; and

after crosslinking exposed portions of the azido-functionalized random graft copolymer, selectively removing non-crosslinked portions of the azido-functionalized random graft copolymer to expose portions of the substrate.

21. The method of claim 19, wherein:

the polystyrene-b-ethylene oxide) block copolymer is a cylindrical-phase block copolymer, and

annealing the polymer material forms perpendicular-oriented cylindrical polymer domains on the portions of the crosslinked azido-functionalized random graft copolymer and parallel-oriented half-cylindrical domains on the exposed portions of the substrate.