Electrochemical etching

• US 20060207890A1
• Filed: 03/15/2005
• Published: 09/21/2006
• Est. Priority Date: 03/15/2005
• Status: Abandoned Application

• Current Assignee: WD Media Incorporated (Western Digital Corporation)
• Original Assignee: WD Media Incorporated (Western Digital Corporation)
• Inventors: Staud, Norbert
• Application Number:
  US11/081,762
• Publication Number:
  US 20060207890A1
• Time in Patent Office: Days
• US Class Current: 205/674
• CPC Class Codes: C25F 3/02 Etching
• CPC Class Codes: C25F 3/14 locally

Abstract

Methods to etch a workpiece are described. In one embodiment, a workpiece is disposed within an etchant solution having a composition comprising a dilute acid and a non-ionic surfactant. An electric field is generated within the etchant solution to cause an anisotropic etch pattern to form on a surface of the workpiece.

Claims

1. A method, comprising:

disposing a workpiece within an etchant solution having a composition comprising a dilute acid and a non-ionic surfactant; and

generating an electric field within the etchant solution to cause an anisotropic etch pattern to form on a surface of the workpiece.

2. The method of claim 1, wherein the dilute acid is selected from a group consisting of citric acid and oxalic acid.

3. The method of claim 1, wherein the non-ionic surfactant comprises an alkyl ethoxylate or an alkyl ethoxylate blend.

4. The method of claim 3, wherein the alkyl ethoxylate includes a C7-C10 alkyl chain and a molecular weight of about 550.

5. The method of claim 1, wherein the etchant solution comprises a citric acid and an alkyl ethoxylate blend.

6. The method of claim 1, wherein the dilute acid of the etchant solution has a pH value between about 2 to 4 and a pK value greater than 2.

7. The method of claim 1, wherein disposing further comprises submerging the workpiece in a bath of the etchant solution, the bath also having an electrode disposed adjacent to the workpiece, the electrode and workpiece coupled to a power supply.

8. The method of claim 7, wherein generating the electric field further comprises applying a current between about 0.05 amp to 2.0 amp to the electrode and workpiece.

9. The method of claim 7, wherein generating the electric field further comprises applying a current density between about 50-150 mA/cm².

10. The method of claim 8, wherein applying the current further comprises generating an etch rate between about 5 nm/sec to about 20 nm/sec.

11. The method of claim 7, wherein submerging further comprises forming a space about 1 mm to about 10 mm between the workpiece and the electrode.

12. The method of claim 8, wherein applying the current produces an aspect ratio value of greater than 1 for an etch depth relative to an etch width on the surface of the workpiece.

13. The method of claim 1, wherein the workpiece comprises a disk substrate, and wherein disposing further comprises plating a NiP layer over the disk substrate.

14. The method of claim 13, wherein plating further comprises depositing an embossable layer over the NiP layer.

15. The method of claim 14, wherein depositing further comprises imprinting the embossable layer with a stamper having a template of an etch pattern to be formed on the NiP layer.

16. The method of claim 15, wherein the etch pattern comprises a DTR pattern.

17. The method of claim 16, wherein stamping further comprises ashing the embossable layer to expose the NiP layer in the recessed areas.

18. The method of claim 17, wherein generating the electric field further comprises forming a plurality of recessed areas on the surface of the NiP layer corresponding to the DTR pattern.

48. The etchant of claim 1, wherein the dilute acid is selected from a group comprising citric acid and oxalic acid.

19. A method, comprising:

disposing a workpiece within an etchant solution having a composition comprising a dilute acid, a non-ionic surfactant, and an adsorbate; and

generating an electric field within the etchant solution to cause an anisotropic etch pattern to form on a surface of the workpiece.

20. The method of claim 19, wherein the adsorbate comprises alkylbenzene sulfonic acid.

21. The method of claim 19, wherein the adsorbate comprises 2-benzimidazole proprionic acid.

22. The method of claim 19, wherein the dilute acid is selected from a group consisting of citric acid and oxalic acid.

23. The method of claim 19, wherein the non-ionic surfactant comprises an alkyl ethoxylate or an alkyl ethoxylate blend.

24. The method of claim 23, wherein the alkyl ethoxylate includes a C7-C10 alkyl chain and a molecular weight of about 550.

25. The method of claim 19, wherein the etchant solution comprises a citric acid, an alkyl ethoxylate blend, and an alkylbenzene sulfonic acid.

26. The method of claim 19, wherein the dilute acid of the etchant solution has a pH value between about 2 to 4 and a pK value greater than 2.

27. The method of claim 19, wherein disposing further comprises submerging the workpiece in a bath of the etchant solution, the bath also having an electrode disposed adjacent to the workpiece, the electrode and workpiece coupled to a power supply.

28. The method of claim 27, wherein generating the electric field further comprises applying a current between about 0.05 amp to 2.0 amp to the electrode and workpiece.

29. The method of claim 27, wherein generating the electric field further comprises applying a current density between about 50-150 mA/cm².

30. The method of claim 28, wherein applying the current further comprises generating an etch rate between about 5 nm/sec to about 20 nm/sec.

31. The method of claim 27, wherein submerging further comprises forming a space about 1 mm to about 10 mm between the workpiece and the electrode.

32. The method of claim 28, wherein applying the current produces an aspect ratio value of greater than 1 for an etch depth relative to an etch width on the surface of the workpiece.

33. The method of claim 19, wherein the workpiece comprises a disk substrate, and wherein disposing further comprises plating a NiP layer over the disk substrate.

34. The method of claim 33, wherein plating further comprises depositing an embossable layer over the NiP layer.

35. The method of claim 34, wherein depositing further comprises imprinting the embossable layer with a stamper having a template of a etch pattern to be formed on the NiP layer.

36. The method of claim 35, wherein the etch pattern comprises a DTR pattern.

37. The method of claim 34, wherein stamping further comprises ashing the embossable layer to expose the NiP layer in the recessed areas.

38. The method of claim 37, wherein generating the electric field further comprises forming a plurality of recessed areas on the surface of the NiP layer corresponding to the DTR pattern.

39. An electrochemical etchant, comprising:

a solution of about 0.35% to about 3.5% of a dilute acid and a non-ionic surfactant.

40. The etchant of claim 39, wherein the non-ionic surfactant comprises an alkyl ethoxylate blend with a C7 to C10 alkyl chain and a molecular weight of about 550.

41. The etchant of claim 39, wherein the dilute acid comprises citric acid and the non-ionic surfactant comprises an alkyl ethoxylate blend.

42. The etchant of claim 39, wherein the dilute acid has a pH value between about 2 to 4 and a pK value greater than 2.

43. The etchant of claim 39, wherein the dilute acid is selected from a group comprising citric acid and oxalic acid.

44. An electrochemical etchant, comprising:

a solution of about 0.35% to about 3.5% of a dilute acid, a non-ionic surfactant, and a nickel adsorbate.

45. The etchant of claim 44, wherein the non-ionic surfactant comprises an alkyl ethoxylate blend with a C7 to C10 alkyl chain and a molecular weight of about 550.

46. The etchant of claim 44, wherein the dilute acid comprises citric acid, the non-ionic surfactant comprises an alkyl ethoxylate blend, and the nickel adsorbate comprises an alkylbenzene sulfonic acid.

47. The etchant of claim 44, wherein the dilute acid has a pH value between about 2 to 4 and a pK value greater than 2.

49. The etchant of claim 44, wherein the nickel adsorbate is selected from a group comprising alkylbenzene sulfonic acid and 2-benzimidazole proprionic acid.

50. An apparatus, comprising:

means for disposing a workpiece within an etchant solution having a composition comprising a dilute acid and a non-ionic surfactant; and

means for generating an electric field within the etchant solution to cause an anisotropic etch pattern to form on a surface of the workpiece.

51. The apparatus of claim 50, wherein the dilute acid is selected from a group consisting of citric acid and oxalic acid.

52. The apparatus of claim 50, wherein the non-ionic surfactant comprises an alkyl ethoxylate or an alkyl ethoxylate blend.

53. The apparatus of claim 50, wherein means for disposing further comprises means for submerging the workpiece in a bath of the etchant solution, the bath also having an electrode disposed adjacent to the workpiece, the electrode and workpiece coupled to a power supply.

54. The apparatus of claim 53, wherein means for generating the electric field further comprises means for applying a current between about 0.05 amp to 2.0 amp to the electrode and workpiece.

55. The apparatus of claim 54, wherein means for applying the current further comprises means for generating an etch rate between about 5 nm/sec to about 20 nm/sec.

56. The apparatus of claim 54, wherein means for applying the current produces an aspect ratio value of greater than 1 for an etch depth relative to an etch width on the surface of the workpiece.

57. The apparatus of claim 50, wherein the workpiece comprises a disk substrate, and wherein means for disposing further comprises means for plating a NiP layer over the disk substrate.

58. The apparatus of claim 57, wherein means for plating further comprises means for depositing an embossable layer over the NiP layer.

59. The apparatus of claim 58, wherein means for depositing further comprises means for imprinting the embossable layer with a stamper having a template of a etch pattern to be formed on the NiP layer to form raised areas and recessed areas on the embossable layer.

60. The apparatus of claim 59, wherein means for stamping further comprises means for ashing the embossable layer to expose the NiP layer in the recessed areas.

61. The apparatus of claim 60, wherein means for generating the electric field further comprises means for forming a plurality of recessed areas on the surface of the NiP layer corresponding to a DTR pattern.