Smooth structures for heat-assisted magnetic recording media

Patent metadata

Field	Value
Publication number	US-9449633-B1
Application number	US-201414535130-A
Country	US
Kind code	B1
Filing date	Nov 6, 2014
Priority date	Nov 6, 2014
Publication date	Sep 20, 2016
Grant date	Sep 20, 2016

Abstract

A recording medium having improved signal-to-noise ratio (SNR) capabilities and head-disk interface characteristics includes an etched smoothened underlayer, over which the recording layer is grown. One mechanism for increasing the SNR is by growing more columnar magnetic grain structures within the recording layer, which is facilitated by a smoother underlayer template.

First claim

What is claimed is:

1. A heat-assisted magnetic recording (HAMR) medium comprising:
a substrate;
a heat sink layer over said substrate, wherein said heat sink layer has a thickness such that a high thermal gradient is achieved in said HAMR medium;
an etched underlayer over said heat sink layer, wherein said etched underlayer comprises an etched, smoothed surface; and
a magnetic recording layer over said underlayer.

2. The HAMR medium of claim 1 , wherein said etched underlayer is a physically-etched underlayer.

3. The HAMR medium of claim 2 , wherein said physically-etched underlayer is a plasma-etched underlayer.

4. The HAMR medium of claim 1 , wherein said etched underlayer provides a substantially smooth etched surface on which a more columnar FePt magnetic recording layer is grown than would otherwise grow on an un-etched underlayer.

5. The HAMR medium of claim 1 , wherein an average surface roughness (R a ) of said etched underlayer is reduced, by etching, by at least about 0.4 angstrom.

6. The HAMR medium of claim 5 , wherein said average surface roughness (R a ) of said etched underlayer is reduced by a particular amount as measured using atomic force microscopy.

7. The HAMR medium of claim 1 , wherein an average surface roughness (R a ) of said etched underlayer is approximately equal to an average surface roughness of said substrate.

8. The HAMR medium of claim 1 , wherein a maximum profile peak height (R p ) of surface asperities of said etched underlayer is reduced, by etching, by at least about 5 angstrom.

9. The HAMR medium of claim 1 , wherein a vertical-axis dispersion of said magnetic recording layer is reduced, by etching said underlayer, by at least about 0.7 degrees.

10. A data storage device comprising:
a heat-assisted magnetic recording (HAMR) disk medium rotatably mounted on a spindle, said HAMR disk medium comprising:
a substrate,
a heat sink layer over said substrate, wherein said heat sink layer has a thickness such that a high thermal gradient is achieved in said HAMR disk medium,
an etched underlayer over said heat sink layer, wherein said etched underlayer comprises an etched, smoothed surface, and
a magnetic recording layer over said etched underlayer;

a heat-assisted magnetic recording (HAMR) head slider comprising a magnetic write head configured to write to said HAMR disk medium;
a heat source coupled with said slider; and
a voice coil motor actuator configured to move said HAMR head slider to access portions of said HAMR disk medium.

11. The data storage device of claim 10 , wherein said etched underlayer of said HAMR disk medium is a physically-etched underlayer.

12. The data storage device of claim 10 , wherein said etched underlayer of said HAMR disk medium provides a substantially smooth etched surface on which a more columnar FePt magnetic recording layer is grown than would otherwise grow on an un-etched underlayer.

13. The data storage device of claim 10 , wherein an average surface roughness (R a ) of said etched underlayer of said HAMR disk medium is reduced, by etching, by at least about 0.4 angstrom.

14. The data storage device of claim 10 , wherein an average surface roughness (R a ) of said etched underlayer of said HAMR disk medium is approximately equal to an average surface roughness of said substrate of said HAMR disk medium.

15. The data storage device of claim 10 , wherein a maximum profile peak height (R p ) of surface asperities of said etched underlayer of said HAMR disk medium is reduced, by etching, by at least about 5 angstrom.

16. The data storage device of claim 10 , wherein a vertical-axis dispersion of said magnetic recording layer of said HAMR disk medium is reduced, by etching said underlayer of said HAMR disk medium, by at least about 0.7 degrees.

17. A method of manufacturing a heat-assisted magnetic recording medium, the method comprising:
forming a heat sink layer over a substrate;
forming an underlayer over said heat sink layer;
smoothing said underlayer by etching said underlayer to form a smoothed underlayer; and
forming a magnetic recording layer over said smoothed underlayer, wherein said magnetic recording layer is more columnar than would otherwise grow on an un-smoothed underlayer, and wherein forming said magnetic recording layer over said smoothed underlayer reduces a vertical-axis dispersion of said magnetic recording layer by at least about 0.7 degrees compared to a magnetic recording layer that would otherwise grow on said un-smoothed underlayer.

18. The method of claim 17 , wherein smoothing said underlayer includes reducing the average surface roughness (R a ) of said underlayer by at least about 0.4 angstrom.

19. The method of claim 17 , wherein smoothing said underlayer includes reducing an average surface roughness (R a ) of said underlayer to approximately equal to an average surface roughness of said substrate.

20. The method of claim 17 , wherein smoothing said underlayer includes reducing a maximum profile peak height (R p ) of said underlayer surface asperities by at least about 5 angstrom.

21. The method of claim 17 , wherein smoothing said underlayer reduces an average surface roughness (R a ) of said underlayer and reduces a maximum profile peak height (R p ) of said underlayer surface asperities by a particular amount as measured by atomic force microscopy (AFM).

22. The HAMR medium of claim 1 , wherein said heat sink layer comprises at least one from a group consisting of tungsten (W), ruthenium (Ru), and copper (Cu).

Assignees

• Wd Media Llc

Inventors

• Pirzada Shahid
• Seki Tomoko
• Acharya B Ramamurthy
• Ajan Antony

Classifications

• G11B5/84 Primary

  Processes or apparatus specially adapted for manufacturing record carriers · CPC title

• G11B11/10584

  characterised by the form, e.g. comprising mechanical protection elements · CPC title

• G11B2005/0021

  Thermally assisted recording using an auxiliary energy source for heating the recording layer locally to assist the magnetization reversal · CPC title

• G11B5/314

  where the layers are extra layers normally not provided in the transducing structure, e.g. optical layers (G11B5/3196 takes precedence) · CPC title

• G11B5/732

  Physics · mapped topic