Magnetic recording media with small grain size and narrow c-axis dispersion by using dual seed layer with substrate bias
View Patent ↗Media may be produced with narrow c-axis dispersion while having small grain size and high grain density. A dual seed layer design and a substrate bias voltage may be applied during deposition of the seed layer are used in the media. In some embodiments, the first seed layer is an amorphous material because of a high content of elements with large atomic sizes. Application of the substrate bias during deposition of the second seed layer may reduce the grain size and may narrow c-axis dispersion.
1. A recording medium comprising:
a first seed layer comprising one or more elements having atomic sizes greater than 1.35 Å that constitute between 12 to 39 at. % or between 61 to 80 at. % of the first seed layer;
a second seed layer on the first seed layer;
an interlayer on the second seed layer; and
a region of intermixing between the first seed layer and the second seed layer,
formed via application of a substrate bias voltage;
wherein the second seed layer comprises an alloy of Cr, Mo, and Ni and the first seed layer and second seed layer are formed from different materials.
2. The recording medium of claim 1 , wherein the one or more elements having atomic sizes greater than 1.35 Å comprise Ta, Zr, Ti, W, Mo or Nb; and wherein the first seed layer further comprises Ni, Co, Cr or Fe.
3. The recording medium of claim 1 , wherein the first seed layer is amorphous.
4. The recording medium of claim 1 , wherein the second seed layer has a face-centered cubic structure with (111) orientation with respect to a surface plane of the recording medium or a hexagonal close packed structure with (0001) orientation with respect to the surface plane of the recording medium.
5. The recording medium of claim 1 , wherein the first seed layer is between 0.5 and 4 nm thick, the second seed layer is between 2 and 10 nm thick, and the region of intermixing is between 0.5 and 2 nm thick.
6. The recording medium of claim 1 , wherein the second seed layer promotes the interlayer such that the second seed layer has a center-to-center grain size between 3 and 10 nm.
7. A method of manufacturing a recording medium, comprising:
applying a substrate bias voltage before depositing a first seed layer and maintaining the bias voltage during application of the first seed layer and a second seed layer;
depositing the first seed layer over a substrate, the first seed layer comprising one or more elements having atomic sizes greater than 1.35 Å that constitute between 12 to 39 at. % or between 61 to 80 at. % of the first seed layer;
depositing a second seed layer on the first seed layer, such that a region of intermixing occurs between the first seed layer and a second seed layer;
depositing an interlayer on the second seed layer;
wherein the second seed layer comprises an alloy of Cr, Mo, and Ni and the first seed layer and second seed layer are formed from different materials.
8. The method of claim 7 , wherein the substrate bias voltage is maintained during the step of depositing the second seed layer to form the region of intermixing between the first seed layer and the second seed layer.
9. The method of claim 8 , wherein the substrate bias voltage is between −200V and −800V.
10. The method of claim 7 , wherein the one or more elements having atomic sizes greater than 1.35 Å comprise Ta, Zr, Ti, W, Mo or Nb; and wherein the first seed layer further comprises Ni, Co, Cr or Fe.
11. The method of claim 7 , wherein the first seed layer is amorphous.
12. The method of claim 7 , wherein the second seed layer has a face-centered cubic structure with (111) orientation with respect to a surface plane of the recording medium or a hexagonal close packed structure with (0001) orientation with respect to the surface plane of the recording medium.
13. The method of claim 7 , wherein the first seed layer is between 0.5 and 4 nm thick, the second seed layer is between 2 and 10 nm thick, and the region of intermixing is between 0.5 and 2 nm thick.
14. The method of claim 7 , wherein the second seed layer promotes the interlayer such that the second seed layer has a center-to-center grain size between 3 and 10 nm.