Electrochemical etching

• US 9,068,274 B1
• Filed: 12/13/2010
• Issued: 06/30/2015
• Est. Priority Date: 03/15/2005
• Status: Expired due to Fees

• Current Assignee: WD Media Limited (Western Digital Corporation)
• Original Assignee: WD Media Limited (Western Digital Corporation)
• Inventors: Staud, Norbert
• Primary Examiner(s): Michener, Jennifer
• Assistant Examiner(s): Dam, Dustin Q
• Application Number:
  US12/966,859
• Time in Patent Office: 1,660 Days
• Field of Search: 205674-686
• US Class Current: 1/1
• 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, wherein the composition further comprises an adsorbate comprising 2-benzimidazole proprionic acid; 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 having a plated NiP layer over the disk substrate.

14. The method of claim 13, further comprising:

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, wherein the etch pattern comprises a DTR pattern, and 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.

15. The method of claim 14, wherein imprinting further comprises ashing the embossable layer to expose the NiP layer in the recessed areas.