Method for producing single-sided sputtered magnetic recording disks
An information-storage media is provided that includes: (a) a substrate disk 312 having first and second opposing surfaces; (b) a first selected layer 304 on the first surface, the first selected layer having a first thickness; (c) a second selected layer 308 on the second surface, the second selected layer having a second thickness, wherein the first and second selected layers have a different chemical composition than the substrate disk; and (d) an information-storage layer 412 adjacent to one or both of the selected layers. The first and second thicknesses are different to provide an unequal stress distribution across the cross-section of the media.
1. A method for producing an information-storage media disk having first and second interface layers, a first information storage layer on a first side of a substrate disk, and a second information storage layer on second side of the substrate disk, comprising:
depositing the first interface layer on the first side of a substrate disk and the second interface layer on the second side of said substrate disk, respectively, wherein the first and second interface layers have differing chemical compositions, and wherein the first and second interface layers cause the substrate disk to be curved;
controlling curvature of the disk by removing unequal thicknesses from the first and second interface layers, wherein, after the removal step, the first and second interface layers remain, the thickness of the first interface layer being less than the thickness of the second interface layer and the flatness of the first and second sides is from 2 to 10 microns;
subsequently depositing the first information storage layer on the first interface layer and the second information storage layer on the second interface layer; and
controlling curvature of the information-storage media by forming the information-storage layers and the first and second interface layers to provide the information-storage media.
2. The media of claim 1 , wherein the first and second interface layers comprise nickel phosphorus and wherein the other one of the first and second interface layers is not adjacent to the information-storage layer.
3. The media of claim 1 , wherein a first thickness of the first interface layer is no more than about 99.3% of a second thickness of the second interface layer.
4. The media of claim 1 , further comprising controlling curvature of the information-storage media by removing unequal thicknesses from the first and second interface layers wherein after the removal flatness of the first and second sides is from about 2 to about 10 microns, and wherein a first thickness of the first interface layer is no more than about 99.3% of a second thickness of the second interface layer.
5. The media of claim 1 , wherein the information-storage layer is a ferromagnetic material, wherein the information-storage layer is adjacent to the first interface layer, and further comprising:
an underlayer positioned between the information-storage layer and the first interface layer; and
an overcoat layer, wherein the information-storage layer is positioned between the overcoat layer and the underlayer, wherein the information-storage layer and underlayer are each in compression.
6. The media of claim 1 , wherein the first and second interface layers have the same chemical composition and wherein a compressive stress in the first interface layer is less than a compressive stress in the second interface layer.
7. The media of claim 1 , wherein the information-storage layer is adjacent to the second interface layer and the second interface layer is located between the information-storage layer and the substrate, wherein the first side is free of an information-storage layer, and, wherein the information-storage layer is in tension.
8. The media of claim 1 , wherein the first and second interface layers are each in tension and wherein the information-storage layer is in compression.
9. The media of claim 1 , wherein depositing first and second interface layers on first and second sides comprises:
depositing the first interface layer at a first thickness; and
depositing the second interface layer at a second thickness, wherein the first and second thicknesses are different.
10. The media of claim 1 , wherein depositing first and second interface layers on first and second sides comprises:
depositing the first and second interface layers on the substrate disk, wherein, after the depositing step, the thicknesses of the first and second interface layers are substantially the same.
11. The media of claim 1 , wherein the removing step comprises:
rough polishing only one of the first and second sides of the first and second interface layers.
12. The media of claim 1 , wherein the removing step comprises:
fine polishing only one of the first and second sides of the first and second interface layers.
13. The media of claim 1 , wherein the removing step comprises:
rough polishing only one of the first and second sides of the first and second interface layers to remove a first thickness of the corresponding first and second interface layer; and
fine polishing the only one of the first and second sides to remove a second thickness of the corresponding first and second interface layer.