Electrochemical etching

• US 7,569,490 B2
• Filed: 03/15/2005
• Issued: 08/04/2009
• Est. Priority Date: 03/15/2005
• Status: Expired due to Fees

• Current Assignee: WD Media Incorporated (Western Digital Corporation)
• Original Assignee: WD Media Incorporated (Western Digital Corporation)
• Inventors: Staud, Norbert
• Primary Examiner(s): Vinh; Lan
• Application Number:
  US11/081,326
• Publication Number:
  US 20060207889A1
• Time in Patent Office: 1,603 Days
• Field of Search: 438/745, 438/750, 438/752, 205/640.644
• US Class Current: 438/745
• 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 an adsorbate, wherein the adsorbate comprises 2-benzimidazole proprionic acid;

generating an electric field within the etchant solution; and

anisotropically etching a pattern in a NiP surface of the workpiece.

2. 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.

3. 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.

4. The method of claim 3, wherein generating the electric field further comprises applying a current between about 0.05 amp to 2.0 amp to the electrode and workpiece.

5. The method of claim 3, wherein generating the electric field further comprises applying a current between about 0.05 amp to 2.0 amp to the electrode and workpiece.

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

7. The method of claim 5, 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.

8. The method of claim 3, wherein submerging further comprises forming a space of about 1 mm to about 10 mm between the workpiece and the electrode.

9. The method of claim 1, wherein the workpiece comprises a disk substrate, and wherein the method, before disposing the workpiece within the etchant, further comprises:

plating the NiP layer over the disk substrate;

depositing an embossable layer over the NiP layer; and

imprinting the embossable layer with a stamper having a template of an etch pattern to be formed on the NiP layer.

10. The method of claim 9, wherein the etch pattern comprises a discrete track recording (DTR) pattern.

11. The method of claim 1, wherein the etchant solution further comprises a non-ionic surfactant.

12. The method of claim 11, wherein the non-ionic surfactant comprises an alkyl ethoxylate or an alkyl ethoxylate blend.

13. The method of claim 12, wherein the alkyl ethoxylate includes a C7-C10 alkyl chain and a molecular weight of about 550.

14. A method, comprising:

disposing a workpiece within an etchant solution having a composition comprising a dilute acid and an adsorbate, wherein the workpiece comprises a disk substrate having a plated Nip layer over the disk substrate;

generating an electric field within the etchant solution; and

anisotropically etching a pattern in a surface of the workpiece.

15. The method of claim 14, wherein the dilute acid is selected from the group consisting of citric acid and oxalic acid.

16. The method of claim 14, wherein the dilute acid of the etchant solution has a pH value between about 2 to 4 and a pK value greater than 2.

17. The method of claim 14, 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.

18. The method of claim 17, wherein generating the electric field further comprises applying a current between about 0.05 amp to 2.0 amp to the electrode and workpiece.

19. the method of claim 18, wherein applying the current further comprises generating an etch rate between about 5 nm/sec to about 20 nm/sec.

20. The method of claim 18, 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.

21. the method of claim 17, wherein generating the electric field further comprises applying a current between 0.05 amp to the electrode and workpiece.

22. The method of claim 17, wherein submerging further comprises forming a space about 1 mm to about 10 mm between the workpiece and the electrode.

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

24. The method of claim 23, 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.

25. The method of claim 24, wherein the etch pattern comprises a discrete track recording (DTR) pattern.

26. The method of claim 25, wherein stamping further comprises ashing the embossable layer to expose the NiP layer in the recessed areas.

27. The method of claim 26, 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.

28. the method of claim 14, wherein the etchant solution further comprises a non-ionic surfactant.

29. the method of claim 28, wherein the non-ionic surfactant comprises an alkyl ethoxylate or an alkyl ethoxylate blend.

30. The method of claim 29, wherein the alkyl ethoxylate includes a C7-C10 alkyl chain and a molecular weight of about 550.

31. A method, comprising:

disposing a workpiece within an etchant solution having a composition comprising a dilute acid and an adsorbate, wherein the adsorbate comprises 2-benzimidazole proprionic acid;

generating an electric field within the etchant; and

anisotropically etching a pattern in a surface of the workpiece, wherein the workpiece comprises a disk substrate, and wherein the method, before disposing the workpiece within the etchant, further comprises;

plating a NiP layer over the disk substrate;

depositing an embossable layer over the NiP layer; and

imprinting the embossable layer with a stamper having a template of an etch pattern to be formed on the NiP layer.

32. The method of claim 31, wherein the etch pattern comprises a discrete track recording (DTR) pattern.