Formation of close-packed sphere arrays in V-shaped grooves

• US 7,790,045 B1
• Filed: 09/13/2007
• Issued: 09/07/2010
• Est. Priority Date: 09/13/2006
• Status: Active Grant

• Current Assignee: Massachusetts Institute of Technology
• Original Assignee: Massachusetts Institute of Technology
• Inventors: Ross, Caroline A., Chuang, Peng-Wei
• Primary Examiner(s): ALANKO, ANITA KAREN
• Application Number:
  US11/854,872
• Time in Patent Office: 1,090 Days
• Field of Search: None
• US Class Current: 216/2
• 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: Y10S 977/888 Shaping or removal of materials, e.g. etching
• CPC Class Codes: Y10S 977/895 having step or means utilizing chemical property
• CPC Class Codes: Y10S 977/90 having step or means utilizing mechanical or thermal property, e.g. pressure, heat
• CPC Class Codes: Y10T 428/2457 Parallel ribs and/or grooves
• CPC Class Codes: Y10T 428/2462 with partial filling of valleys on outer surface

Abstract

The present invention relates to the self-assembly of a spherical-morphology block copolymer into V-shaped grooves of a substrate. Although spherical morphology block copolymers typically form a body-centered cubic system (bcc) sphere array in bulk, the V-shaped grooves promote the formation of a face-centered cubic system (fcc) sphere array that is well ordered. In one embodiment, the (111) planes of the fcc sphere array are parallel to the angled side walls of the V-shaped groove. The (100) plane of the fcc sphere array is parallel to the top surface of the substrate, and may show a square symmetry among adjacent spheres. This square symmetry is unlike the hexagonal symmetry seen in monolayers of spherical domains and is a useful geometry for lithography applications, especially those used in semiconductor applications.

Claims

1. A method comprising:

providing a substrate having at least one V-shaped groove formed at least in part by two angled side walls; and

applying a self-assembling block copolymer in the at least one V-shaped groove, an angle of the walls for the at least one V-shaped groove and the block copolymer selected such that the block copolymer forms a face-centered cubic system (fcc) sphere array of close-packed spheres within the at least one V-shaped groove.

2. The method of claim 1 wherein the providing the substrate further comprises etching the at least one V-shaped groove in the substrate.

3. The method of claim 1 wherein the at least one V-shaped groove is etched in a (100) oriented substrate wherein (100) is a Miller index.

4. The method of claim 1 wherein the at least one V-shaped groove is formed by (111) oriented planes of the substrate wherein (111) is a Miller index.

5. The method of claim 4 wherein an angle formed by the two angled side walls is about 70.6 degrees.

6. The method of claim 1 wherein the substrate is a silicon wafer.

7. The method of claim 1 wherein the substrate comprises a plurality of V-shaped grooves including the at least one V-shaped groove, and mesas are provided on a top surface of the substrate between adjacent ones of the plurality of V-shaped grooves.

8. The method of claim 7 wherein the fcc sphere array of close-packed spheres formed in each of the plurality of V-shaped grooves does not cover the mesas.

9. The method of claim 1 wherein the fcc sphere array of close-packed spheres maintains order throughout the at least one V-shaped groove.

10. The method of claim 1 wherein respective (111) and (11 1) oriented planes of the fcc sphere array of close-packed spheres are parallel to the two angled side walls of the at least one V-shaped groove, and wherein (111) and (11 1) are Miller indexes.

11. The method of claim 1 wherein a (001) oriented plane of the fcc sphere array of close-packed spheres is parallel to a top surface of the substrate, and wherein (001) is a Miller index.

12. The method of claim 1 wherein a ( 110) oriented plane of the fcc sphere array of close-packed spheres is perpendicular to a length of the at least one V-shaped groove, and wherein ( 110) is a Miller index.

13. The method of claim 1 wherein a top layer of spheres in the fcc sphere array of close-packed spheres provides a substantially square symmetry among adjacent spheres of the sphere array.

14. The method of claim 1 wherein a diameter of spheres in a top layer of spheres in the fcc sphere array is smaller than a diameter of spheres in underlying layers of spheres in the fcc sphere array.

15. The method of claim 1 wherein a top layer of spheres in the fcc sphere array loses an epitaxial relationship with underlying layers of spheres in the fcc sphere array.

16. The method of claim 1 wherein the fcc sphere array comprises a plurality of layers of spheres.

17. The method of claim 16 wherein the fcc sphere array comprises more than three layers of spheres.

18. The method of claim 1 wherein for the at least one V-shaped groove, the two angled side walls come to a point at a bottom of the at least one V-shaped groove.

19. The method of claim 1 wherein the self-assembling block copolymer is a diblock copolymer.

20. The method of claim 1 wherein one block of the block copolymer comprises at least one of polystyrene, polyferrocenyldimethylsilane, poly(methyl methacrylate), poly(dimethyl-siloxane), poly(2-vinyl pyridine), and polybutadiene.

21. The method of claim 1 wherein the block copolymer has a spherical morphology.