Magnetically patterned etch mask

• US 6,174,449 B1
• Filed: 05/14/1998
• Issued: 01/16/2001
• Est. Priority Date: 05/14/1998
• Status: Expired due to Fees

• Current Assignee: Micron Technology, Inc.
• Original Assignee: Micron Technology, Inc.
• Inventors: Knappenberger, Eric, Alwan, James J.
• Primary Examiner(s): Gulakowski, Randy
• Assistant Examiner(s): OLSEN, ALLAN W
• Application Number:
  US09/079,252
• Time in Patent Office: 978 Days
• Field of Search: 216/12, 216/22, 216/42, 427/547, 430/39
• US Class Current: 216/42
• CPC Class Codes: H01J 9/025 of field emission cathodes
• CPC Class Codes: H01L 21/0337 characterised by the process involved to create the mask, e.g. lift-off masks, sidewalls, or to modify the mask, e.g. pre-treatment, post-treatment

Abstract

A method for forming an etch mask is described. In particular, an etch mask is formed using masking particles positionally restrained by a matrix medium. Either the masking particles or the matrix medium is more magnetically conductive with respect to the other. A magnetic field is applied for making a random distribution of the masking particles less random. Consequently, agglomeration of the masking particles is reduced. Masking particles with submicron dimensions may be used for providing features of less than a micron. The mask formed may be an etch mask employed in forming a field emitter tip for a field emission display.

Claims

1. A process for providing a masking layer, comprising:

providing a substrate assembly;

dispensing a matrix material and a plurality of objects onto the substrate assembly;

distributing the objects with a magnetic field; and

removing at least a portion of the matrix material.

2. A process, as in claim 1, wherein dispensing comprises providing the matrix material in a liquid state.

3. A process, as in claim 2, further comprising curing the matrix material after distributing the objects.

4. A process, as in claim 3, wherein curing comprises altering the liquid state of the matrix material sufficiently to maintain the distribution of the objects.

5. A process, as in claim 3, wherein curing comprises forming a polymer form of the matrix material.

6. A process, as in claim 3, wherein curing comprises forming a solid form of the matrix material.

7. A process, as in claim 1, wherein dispensing comprises at least one of depositing, spraying, spreading, dipping, evaporating, and spinning the matrix material onto the substrate assembly.

8. A process, as in claim 1, wherein the objects include at least one of particles, microballs, droplets, and beads.

9. A process for providing an etch mask, comprising:

providing a substrate assembly;

dispensing matrix material and masking objects onto the substrate assembly, the matrix material being less magnetically permeable than the masking objects; and

applying a magnetic field to the masking objects sufficient to relocate the objects.

10. A process, as in claim 9, wherein the matrix material includes at least one of an elastomer, an adhesive, a thermoplastic, and a glass.

11. A process, as in claim 9, wherein the matrix material is a liquid.

12. A process, as in claim 9, wherein the matrix material is a polymeric material.

13. A process, as in claim 12, wherein the polymeric material includes at least one of silicone rubber, epoxy, resin, and polyurethane.

14. A process, as in claim 9, further comprising curing the matrix material for at least one of solidification, gelation, and polymerization.

15. A process, as in claim 9, wherein the masking objects include ferromagnetic material.

16. A process, as in claim 9, wherein the masking objects are composed at least in part of a ferrite.

17. A process for providing an etch mask, comprising:

providing a substrate assembly;

dispensing a matrix material and masking objects onto the substrate assembly, the matrix material being more magnetically permeable than the masking objects; and

applying a magnetic field to the matrix material sufficient to disperse the masking objects.

18. A process, as in claim 17, wherein the masking objects are composed at least in part of silica.

19. A process, as in claim 17, wherein the masking objects are composed at least in part of latex.

20. A process, as in claim 17, wherein the matrix material is a ferromagnetic liquid.

21. A process, as in claim 20, wherein the masking objects are composed at least in part of magnetite.

22. A process for forming an etch mask, comprising:

providing a substrate assembly;

dispensing masking objects on the substrate assembly;

dispensing a matrix material on the substrate assembly; and

applying a magnetic field to disperse the masking objects within the matrix material.

23. A process, as in claim 22, wherein some of the masking objects and the matrix material are dispensed simultaneously.

24. A process, as in claim 22, wherein the masking objects are dispensed prior to dispensing the matrix material.

25. A process, as in claim 22, wherein the step of dispensing the matrix material is done prior to the step of dispensing the masking objects.

26. A process, as in claim 22, further comprising, prior to dispensing of the masking objects and the matrix material, mixing the matrix material and the masking objects to form a suspension.

27. A process for forming an etch mask, comprising:

dispensing masking objects on a substrate assembly, at least some of the masking objects forming a number of clusters; and

applying a magnetic field to the masking objects to reduce the number of clusters thereof.

28. A process, as in claim 27, wherein applying the magnetic field comprises aligning magnetic poles of the masking objects to provide anisotropically conductive orientations thereof.

29. A process, as in claim 27, wherein applying the magnetic field comprises providing a blanket magnetic field.

30. A process, as in claim 27, wherein the magnetic field is a applied using a grid.

31. A process, as in claim 27, wherein applying is effected using permanent magnets.

32. A process, as in claim 27, wherein applying is effected using electromagnets.

33. A process for providing a mask on a surface of a substrate assembly, comprising:

locating spacer objects on the surface of the substrate assembly;

locating masking objects on the surface of the substrate assembly; and

applying a magnetic field to the spacer objects and the masking objects located on the surface of the substrate assembly to alter a distribution thereof.

34. The process of claim 33, wherein the spacer objects are less magnetically conductive than the masking objects.

35. The process of claim 33, further comprising dispensing a matrix material over the surface to suspend the masking objects and the spacer objects thereabove.

36. The process of claim 33, further comprising dispensing a matrix material over the surface to restrict movement of the masking objects and the spacer objects thereover.

37. The process of claim 33, further comprising dispensing a matrix material to enhance movement of the masking objects and the spacer objects.