Electrochemical etching
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.
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/cm 2 .
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.
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/cm 2 .
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.
48 . The etchant of claim 1 , wherein the dilute acid is selected from a group comprising citric acid and oxalic acid.
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.