Two-dimensional arrays of holes with sub-lithographic diameters formed by block copolymer self-assembly

• US 8,394,483 B2
• Filed: 01/24/2007
• Issued: 03/12/2013
• Est. Priority Date: 01/24/2007
• Status: Active Grant

• Current Assignee: Micron Technology, Inc.
• Original Assignee: Micron Technology, Inc.
• Inventors: Millward, Dan B.
• Primary Examiner(s): CAIN, EDWARD J
• Application Number:
  US11/657,273
• Publication Number:
  US 20080176767A1
• Time in Patent Office: 2,239 Days
• Field of Search: 428/105, 428/113, 977/778, 977/784, 977/789, 977/790
• US Class Current: 428/105
• 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: H01L 21/67103 mainly by conduction
• CPC Class Codes: H05B 3/145 Carbon only, e.g. carbon black, graphite
• CPC Class Codes: H05B 3/24 heating conductor being self-supporting
• CPC Class Codes: Y10T 29/49083 Heater type
• CPC Class Codes: Y10T 428/24058 including grain, strips, or filamentary elements in respective layers or components in angular relation
• CPC Class Codes: Y10T 428/24124 Fibers
• 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

Abstract

Methods for fabricating sublithographic, nanoscale microstructures in two-dimensional square and rectangular arrays utilizing self-assembling block copolymers, and films and devices formed from these methods are provided.

Claims

1. A method for fabricating nanoscale microstructures, comprising:

forming a copolymer film comprising a self-assembling block copolymer within a plurality of trenches to a thickness of about L_o each trench having a width of about L_o, a length of about nL_o, a pitch distance between adjacent trenches of at least about 2*L_o, preferential wetting sidewalls and ends, and a neutral wetting floor, with ends of the trenches aligned; and

causing the copolymer film to form a single array of perpendicularly oriented cylindrical domains of a first polymer block of the block copolymer in a matrix of a second polymer block of the block copolymer within each trench of the plurality, wherein the pitch distance between each cylindrical domain within a trench is about L_o, and the pitch distance between the cylindrical domains of adjacent trenches is about 2*L_o.

2. The method of claim 1, wherein the block copolymer comprises a blend of the block copolymer with a homopolymer of the first polymer block, the second polymer block, or both.

3. The method of claim 1, wherein the block copolymer comprises polystyrene and polymethyl methacrylate.

4. The method of claim 1, wherein the block copolymer comprises an about 60:

40 to about 80;

20 ratio of the first polymer block to the second polymer block.

5. The method of claim 1, wherein the sidewalls and ends comprise an oxide.

6. The method of claim 1, further comprising applying a neutral wetting material to the floors of the plurality of trenches.

7. The method of claim 6, further comprising applying a preferential wetting material to the sidewalls and ends of the plurality of trenches.

8. The method of claim 1, wherein the neutral wetting floor comprises a layer of a random copolymer.

9. The method of claim 8, further comprising applying a layer of a neutral wetting random copolymer onto the floors of the plurality of trenches.

10. The method of claim 1, wherein the neutral wetting floor comprises hydrogen-terminated silicon.

11. The method of claim 1, further comprising, after causing the copolymer film to form the single array of perpendicularly oriented cylindrical domains of the first polymer block, selectively removing the first polymer block to provide a rectangular array of cylindrical openings extending through the matrix of the second polymer block of the copolymer film.

12. The method of claim 11, further comprising etching a substrate through the rectangular array of cylindrical openings in the copolymer film.

13. The method of claim 1, further comprising selectively removing the second polymer block to provide a rectangular array of cylinders masking portions of a substrate.

14. The method of claim 13, further comprising etching unmasked portions of the substrate.

23. The method of claim 1, wherein causing the copolymer film to form a single array of perpendicularly oriented cylindrical domains of a first polymer block of the block copolymer in a matrix of a second polymer block of the block copolymer within each trench of the plurality comprises annealing the copolymer film to form the single array of perpendicularly oriented cylindrical domains of the first polymer block in the matrix of the second polymer block.

24. The method of claim 1, wherein causing the copolymer film to form a single array of perpendicularly oriented cylindrical domains of a first polymer block of the block copolymer in a matrix of a second polymer block of the block copolymer within each trench of the plurality comprises causing a microphase separation in the block copolymer to form the single array of perpendicularly-oriented cylindrical domains of the first polymer block in the matrix of the second polymer block.

25. The method of claim 1, further comprising, prior to forming the copolymer film within the plurality of trenches:

forming a neutral wetting material layer on a substrate;

forming a material layer on the neutral wetting material layer; and

forming a plurality of trenches in the material layer.

26. The method of claim 1, further comprising, after causing the copolymer film to form a single array of perpendicularly oriented cylindrical domains of the first polymer block in the matrix of the second polymer block:

cross-linking the copolymer film within each of the trenches of the plurality to form a first cross-linked copolymer film;

forming a second plurality of trenches by removing a material layer such that each trench of said second plurality of trenches is situated between the cross-linked copolymer films, each trench of the second plurality of trenches having a width of about L_o, a length of about nL_o, a pitch distance of at least about L_o between adjacent trenches, preferential wetting sidewalls and ends, and a neutral wetting floor, with the ends of the trenches of the plurality aligned;

forming a second film comprising a self-assembling block copolymer within the second plurality of trenches to a thickness of about L_o; and

causing the second film to form a single array of perpendicularly oriented cylindrical domains of a first polymer block of the block copolymer in a matrix of a second polymer block of the block copolymer within each trench of the second plurality of trenches, wherein the pitch distance between each cylindrical domain within a second trench of the second plurality of trenches and the pitch distance between the cylindrical domains of adjacent trenches is about L_o.

27. The method of claim 1, further comprising, prior to forming the copolymer film,

forming a layer of a neutral wetting material on a preferential wetting substrate;

masking the layer of neutral wetting material to provide a series of masked and unmasked sections, each unmasked section having a width at or about L_o, and each masked section having a width at or about nL_o;

removing the unmasked sections of the layer of neutral wetting material to expose sections of the preferential wetting substrate;

removing the masked section to expose sections of the layer of neutral wetting material;

forming a material layer over the sections of the preferential wetting substrate and the layer of neutral wetting material;

forming the plurality of trenches in the material layer to expose the sections of the preferential wetting substrate and the layer of neutral wetting material such that the sections are in a perpendicular orientation to sidewalls of the trenches, each trench having a width of about L₀ and a length of about m*(n+1)*L_o, where m is the number of sections of the preferential wetting substrate and n is the number of perpendicularly oriented cylinders, and m and n are independently 1-50.

28. The method of claim 27, wherein the block copolymer film forms a single array of cylindrical domains of the first polymer block of the block copolymer in a matrix of the second polymer block of the block copolymer within each trench, and the cylindrical domains on the sections of the layer of neutral wetting material are in a perpendicular orientation to the preferential wetting substrate, and the cylindrical domains on the sections of the layer of preferential wetting material are in a parallel orientation to the substrate.

15. A method for fabricating nanoscale microstructures, comprising:

forming a block copolymer film comprising an about 60;

40 to about 80;

20 ratio of a first polymer block to a second polymer block within a plurality of trenches to a thickness of about L_o, each trench of the plurality having a width of about L_o, a length of about nL_o, a pitch distance between adjacent trenches at least about 2*L_o, preferential wetting sidewalls and ends, and a neutral wetting floor, with ends of the trenches aligned; and

annealing the block copolymer film to form a single array of perpendicularly oriented cylindrical domains of the second polymer block of the block copolymer in a matrix of the first polymer block of the block copolymer within each trench of the plurality, wherein each trench of the plurality contains a single row of n cylindrical domains at a pitch distance of about L_o and substantially parallel to the sidewalls of the trenches of the plurality, with the cylindrical domains of adjacent trenches at a pitch distance of about 2*L_o.

16. A method of forming nanoscale microstructures, comprising:

forming a block copolymer film having a thickness of about L_o within a plurality of trenches within a material layer, wherein each trench of the plurality has a width of at least about L_o, a length of about nL_o, a pitch distance between adjacent trenches of at least about 2*L_o, preferential wetting sidewalls and ends, and a neutral wetting floor, with ends of the trenches aligned, the block copolymer film comprising an about 60;

40 to about 80;

20 ratio of a first polymer block to a second polymer block, and capable of microphase separating upon annealing into cylindrical domains within a matrix; and

causing a microphase separation in the block copolymer to produce a single array of perpendicularly-oriented cylindrical microstructures composed of the second polymer block in a matrix of the first polymer block within each trench, wherein the pitch distance between adjacent cylindrical microstructures within each trench is about L_o and the pitch distance between cylindrical microstructures of adjacent trenches is about 2*L_o.

17. A method for fabricating nanoscale microstructures, comprising:

forming a neutral wetting material layer on a substrate;

forming a material layer on the neutral wetting material layer;

forming a plurality of trenches in the material layer, each trench of the plurality having a width of about L_o, a length of about nL_o, a pitch distance between adjacent trenches of at least about 2*L_o, preferential wetting sidewalls and ends, and a floor defined by the neutral wetting material layer, with ends of the trenches aligned;

forming a copolymer film comprising a self-assembling block copolymer within the plurality of trenches to a thickness of about L_o; and

causing the copolymer film to form a single array of perpendicularly oriented cylindrical domains of a first polymer block of the block copolymer in a matrix of a second polymer block of the block copolymer within each trench, wherein the pitch distance between each cylindrical domain within a trench is about L_o, and the pitch distance between the cylindrical domains of adjacent trenches is about 2*L_o.

18. A method for fabricating nanoscale microstructures, comprising:

forming a first film comprising a self-assembling block copolymer within a first plurality of trenches within a material layer to a thickness of about L_o, each trench of the first plurality having a width of about L_o, a length of about nL_o, a pitch distance between adjacent trenches of at least about 2*L_o, preferential wetting sidewalls and ends, and a neutral wetting floor, with ends of the trenches aligned;

causing the first copolymer film to form a single array of perpendicularly oriented cylindrical domains of a first polymer block of the block copolymer in a matrix of a second polymer block of the block copolymer within each trench of said first plurality of trenches, wherein the pitch distance between each cylindrical domain within a trench is about L_o, and the pitch distance between the cylindrical domains of adjacent first trenches is about 2*L_o;

cross-linking the annealed first block copolymer film within each of the first trenches;

forming a second plurality of trenches by removing the material layer such that each trench of the second plurality of trenches is situated between the annealed and cross-linked first copolymer films within the trenches of the first plurality, each of the trenches of the second plurality having a width of about L_o, a length of about nL_o, a pitch distance between adjacent trenches of the plurality first and second of at least about L_o, preferential wetting sidewalls and ends, and a neutral wetting floor, with the ends of the second plurality of trenches aligned with the ends of the first plurality of trenches;

forming a second film comprising a self-assembling block copolymer within the second plurality of trenches to a thickness of about L_o; and

causing the second copolymer film to form a single array of perpendicularly oriented cylindrical domains of a first polymer block of the block copolymer in a matrix of a second polymer block of the block copolymer within each of the trenches of the second plurality, wherein the pitch distance between each cylindrical domain within a second trench and between the cylindrical domain of adjacent trenches is about L_o.

19. The method of claim 18, wherein the sidewalls of the second plurality of trenches comprise the material layer, the matrix of the annealed first copolymer film, or a combination of both.

20. The method of claim 18, wherein forming the second plurality of trenches comprises exposing the matrix of the annealed first copolymer film to define the sidewalls of the second plurality of trenches.

21. A method of forming nanoscale microstructures, comprising:

depositing a block copolymer within a first plurality of trenches within a material layer to form a first block copolymer film having a thickness of about L_o, wherein each trench has a width of at least about L_o, a length of about nL_o, a pitch distance between adjacent trenches of at least about 2*L_o, preferential wetting sidewalls and ends, and a neutral wetting floor, with ends of the first plurality of trenches aligned, the block copolymer comprising an about 60;

40 to about 80;

20 ratio of a first polymer block to a second polymer block and capable of microphase separating upon annealing into cylindrical domains within a matrix;

causing a microphase separation in the first block copolymer film to produce a single array of perpendicularly-oriented cylindrical microstructures composed of the second polymer block in a matrix of the first polymer block within each of the first plurality of trenches, wherein adjacent cylindrical microstructures within each trench are separated by a pitch distance of about L_o, and cylindrical microstructures of adjacent first trenches are separated by a pitch distance of about 2*L_o;

cross-linking the first block copolymer film within each trench of the first plurality of trenches;

forming a second plurality of trenches by removing the material layer between the cross-linked first copolymer film within the first plurality of trenches, each trench of the second plurality of trenches having a width of about L_o, a length of about nL_o, a pitch distance between adjacent trenches of the first and second plurality of trenches of at least about L_o, preferential wetting sidewalls and ends, and a neutral wetting floor, with the ends of the second plurality of trenches aligned with the ends of the first plurality of trenches;

depositing the block copolymer within the second plurality of trenches to form a second copolymer film having a thickness of about L_o; and

causing a microphase separation in the block copolymer to produce a single array of perpendicularly-oriented cylindrical microstructures composed of the first polymer block in a matrix of the second polymer block within each trench of the second plurality of trenches, wherein adjacent cylindrical microstructures within each trench of the second plurality of trenches and cylindrical microstructures of adjacent trenches of the first plurality are separated by a pitch distance of about L_o.

22. A method for fabricating nanoscale microstructures, comprising:

forming a neutral wetting material layer on a substrate;

forming a material layer on the neutral wetting material layer, the material layer defining a first plurality of trenches, each trench of the first plurality having a width of about L_o, a length of about nL_o, a pitch distance between adjacent trenches of at least about 2*L_o, preferential wetting sidewalls, and a floor defined by the neutral wetting material layer, with ends of the trenches aligned;

forming a first film comprising a self-assembling block copolymer within the trenches of the first plurality to a thickness of about L_o;

annealing the first copolymer film to form a single array of perpendicularly oriented cylindrical domains of a first polymer block of the block copolymer in a matrix of a second polymer block of the block copolymer within each trench of the first plurality, wherein the pitch distance between each cylindrical domain within a trench is about L_o, and the pitch distance between the cylindrical domains of adjacent trenches is about 2*L_o;

cross-linking the first block copolymer film within each trench of the first plurality of trenches;

forming a second plurality of trenches by removing the material layer between the cross-linked first copolymer film within the first plurality of trenches, each trench of the second plurality of trenches having a width of about L_o, a length of about nL_o, a pitch distance between adjacent trenches of the first and second plurality of at least about L_o, preferential wetting sidewalls, and a neutral wetting floor, with the ends of the second plurality of trenches aligned with the ends of the first plurality of trenches;

forming a second copolymer film comprising a self-assembling block copolymer within the second plurality of trenches to a thickness of about L_o; and

causing a microphase separation in the second copolymer film to produce a single array of perpendicularly-oriented cylindrical microstructures composed of a first polymer block in a matrix of a second polymer block within each trench of the second plurality of trenches, wherein adjacent cylindrical microstructures within each trench of the second plurality and cylindrical microstructures of adjacent trenches of the first plurality are separated by a pitch distance of about L_o.