Magnetic thin film medium comprising amorphous sealing layer for reduced lithium migration

• US 6,120,890 A
• Filed: 11/05/1998
• Issued: 09/19/2000
• Est. Priority Date: 12/12/1997
• Status: Expired due to Fees

• Current Assignee: Seagate Technology LLC (Seagate Technology Holdings Plc)
• Original Assignee: Seagate Technology plc (Seagate Technology Holdings Plc)
• Inventors: Leu, Charles, Huang, Liji, Chen, Qixu, Ranjan, Rajiv, Song, Xing
• Primary Examiner(s): KILIMAN, LESZEK B
• Application Number:
  US09/186,074
• Time in Patent Office: 684 Days
• Field of Search: 428/332, 428/336, 428/694 T, 428/694 ST, 428/694 TS, 428/900, 204/192.2, 427/128-131
• US Class Current: 428/332
• CPC Class Codes: G11B 5/7369 Two or more non-magnetic underlayers, e.g. seed layers or barrier layers
• CPC Class Codes: G11B 5/7371 Non-magnetic single underlayer comprising nickel
• CPC Class Codes: G11B 5/73921 Glass or ceramic substrates
• CPC Class Codes: G11B 5/8404 manufacturing base layers
• CPC Class Codes: Y10S 428/90 Magnetic feature
• CPC Class Codes: Y10T 428/26 Web or sheet containing structurally defined element or component, the element or component having a specified physical dimension
• CPC Class Codes: Y10T 428/265 1 mil or less

Abstract

A glass or glass-ceramic substrate comprising about 0.5 to about 32 wt. % Li₂ O is employed as a non-magnetic substrate of a magnetic recording medium. Migration of Li from the substrate to the medium'"'"'s surface is prevented by forming an amorphous NiP sealing layer on the substrate, with an optional adhesion enhancement layer therebetween. Embodiments include surface oxidizing the amorphous NiP sealing layer for enhanced recording performance.

Claims

1. A longitudinal or perpendicular magnetic recording medium comprising:

a substrate comprising a glass or glass-ceramic material containing about 0.5 to about 32 wt. % lithium oxide (Li₂ O);

at least one sealing layer comprising amorphous nickel-phosphorus; and

a magnetic layer, wherein the sealing substantially prevents the migration of Li from the substrate.

2. The longitudinal magnetic recording medium according to claim 1, further comprising:

an underlayer on the sealing layer;

a magnetic layer on the underlayer; and

a carbon-containing protective overcoat on the magnetic layer.

3. The magnetic recording medium according to claim 1, wherein the surface of the sealing layer is oxidized.

4. The magnetic recording medium according to claim 1, further comprising an adhesion enhancement layer on the substrate and the sealing layer on the adhesion enhancement layer.

5. The magnetic recording medium according to claim 4, wherein the adhesion enhancement layer comprises chromium or a chromium-alloy.

6. The magnetic recording medium according to claim 1, wherein the thickness of the sealing layer is about 300 Å

to about 1,000 Å

.

7. The magnetic recording medium according to claim 1, wherein the amorphous nickel-phosphorus sealing layer further comprises about 0.1 wt. % to about 5 wt. % boron, tungsten or niobium.

8. The magnetic recording medium according to claim 2, wherein the surface of the sealing layer is oxidized.

9. The magnetic recording medium according to claim 2, further comprising an adhesion enhancement layer containing chromium or a chromium alloy on the substrate, and the sealing layer on the adhesion enhancement layer.

10. The longitudinal magnetic recording medium according to claim 1, further comprising a chromium-vanadium underlayer on the sealing layer, wherein the magnetic layer comprises an alloy of cobalt, chromium, platinum and tantalum.

11. A method of manufacturing a longitudinal or perpendicular magnetic recording medium, the method comprising:

sputter depositing at least one sealing layer comprising amorphous nickel-phosphorous on a substrate comprising a glass or glass-ceramic material containing about 0.5 to about 32 wt. % lithium oxide (Li₂ O); and

sputter depositing a magnetic layer on the sealing layer;

wherein the sealing layer substantially prevents migration of Li from the substrate.

12. The method according to claim 11, comprising sputter depositing the sealing layer using a target containing at least 12 wt. % phosphorous.

13. The method according to claim 11, wherein the at least one amorphous nickel-phosphorous layer comprises about 0.1 to about 5 wt. % of boron, tungsten or niobium.

14. The method according to claim 11, further comprising:

sputter depositing an adhesion enhancement layer comprising chromium or a chromium alloy on the substrate; and

sputter depositing the at least one sealing layer on the adhesion enhancement layer.

15. The method according to claim 11, further comprising oxidizing an exposed surface of the at least one sealing layer.

16. The method according to claim 14, further comprising oxidizing an exposed surface of the at least one sealing layer.

17. The method according to claim 15, further comprising:

sputter depositing an underlayer on the sealing layer; and

sputter depositing a magnetic layer on the underlayer.

18. The method according to claim 16, further comprising:

sputter depositing an underlayer on the sealing layer; and

sputter depositing the magnetic layer on the underlayer.

19. The method according to claim 11, wherein the magnetic layer comprises an alloy of cobalt, chromium, platinum and tantalum.

20. The method according to claim 11, comprising sputter depositing the at least one sealing layer to a thickness of about 300 Å

to about 1,000 Å

.