Carbonaceous protective layer, magnetic recording medium, production method thereof, and magnetic disk apparatus

• US 20010029051A1
• Filed: 05/04/2001
• Published: 10/11/2001
• Est. Priority Date: 03/15/2000
• Status: Active Grant

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Yamamoto, Takayuki, Hyodo, Hiroyuki
• Granted Patent: US 6,974,642 B2
• Time in Patent Office: Days
• US Class Current: 438/3
• CPC Class Codes: C23C 14/0605 Carbon
• CPC Class Codes: C23C 14/22 characterised by the process of coating
• CPC Class Codes: C23C 14/325 Electric arc evaporation
• CPC Class Codes: G11B 5/727 Inorganic carbon protective coating, e.g. graphite, diamond like carbon or doped carbon
• CPC Class Codes: G11B 5/8408 protecting the magnetic layer
• CPC Class Codes: H01J 37/32055 Arc discharge

Abstract

A carbonaceous protective layer particularly suitable for use in magnetic recording media. The carbonaceous protective layer is formed by a Filtered Cathodic Arc process, and contains nitrogen distributed therein. A process for the production of a carbonaceous protective layer as well as a magnetic recording medium and a magnetic disk apparatus are also disclosed.

Claims

1. A carbonaceous protective layer for protecting an underlying material, which is a layer formed by a Filtered Cathodic Arc process, and contains nitrogen distributed therein.

2. A carbonaceous protective layer according to

claim 1

, wherein a nitrogen content of said carbonaceous protective layer is 2 to 20 at %.

3. A carbonaceous protective layer according to

claim 1

, wherein nitrogen is distributed in an inclined concentration in said carbonaceous protective layer, and a nitrogen concentration is gradually increased from a bottom surface side to a top surface side in said carbonaceous protective layer.

4. A carbonaceous protective layer according to

claim 1

, wherein nitrogen is not contained in a substantially lower half portion, occupying substantially one half of the thickness-wise distance from a bottom surface of said carbonaceous protective layer.

5. A carbonaceous protective layer according to

claim 1

, wherein a hardness of said carbonaceous protective layer is at least 18 GPa.

6. A carbonaceous protective layer according to

claim 1

, wherein a contact angle of said carbonaceous protective layer to water is not greater than 35°

.

7. A carbonaceous protective layer according to any one of

claims 1

to

6

, wherein said carbonaceous protective layer is positioned over a magnetic recording layer of the magnetic recording medium.

8. A magnetic recording medium comprising a non-magnetic substrate having applied thereon a magnetic recording layer, in which said magnetic recording layer has a carbonaceous protective layer formed thereon by a Filtered Cathodic Arc process, and said carbonaceous protective layer contains nitrogen distributed therein.

9. A magnetic recording medium according to

claim 8

, wherein a nitrogen content of said carbonaceous protective layer is 2 to 20 at %.

10. A magnetic recording medium according to

claim 8

, wherein nitrogen is distributed in an inclined concentration in said carbonaceous protective layer, and a nitrogen concentration is gradually increased from a bottom surface side to a top surface side in said carbonaceous protective layer.

11. A magnetic recording medium according to

claim 8

, wherein nitrogen is substantially not contained in a lower half portion, occupying substantially one half of the thickness-wise distance from a bottom surface of said carbonaceous protective layer.

12. A magnetic recording medium according to

claim 8

, wherein a hardness of said carbonaceous protective layer is at least 18 GPa.

13. A magnetic recording medium according to

claim 8

, wherein a contact angle of said carbonaceous protective layer to water is not greater than 35°

.

14. A method of producing a magnetic recording medium comprising a non-magnetic substrate having applied thereon a magnetic recording layer, which has a carbonaceous protective layer deposited thereon, which method comprises the step of depositing said carbonaceous protective layer on said magnetic recording layer by a Filtered Cathodic Arc process, while introducing nitrogen into said carbonaceous protective layer.

15. A method of producing a magnetic recording medium according to

claim 14

, wherein nitrogen is introduced in said carbonaceous protective layer under the conditions that a nitrogen concentration is gradually increased from a bottom surface side to a top surface side in said carbonaceous protective layer.

16. A method of producing a magnetic recording medium according to

claim 14

, wherein nitrogen is introduced in said carbonaceous protective layer under the conditions that nitrogen is substantially not contained in a lower half portion, occupying substantially one half of the thickness-wise distance from a bottom surface of said carbonaceous protective layer.

17. A method of producing a magnetic recording medium according to any one of

claims 14

to

16

, wherein said carbonaceous protective layer is deposited under irradiation of a nitrogen ion beam, or under the application of a nitrogen atmosphere or by combining them together, thereby introducing nitrogen into said carbonaceous protective layer.

18. A magnetic disk apparatus comprising a recording head for recording information and a reproducing head for reproducing information to and from a magnetic recording medium, in which said magnetic recording medium comprises a non-magnetic substrate having applied thereof a magnetic recording layer, and said magnetic recording layer has a carbonaceous protective layer, formed thereon by a Filtered Cathodic Arc process, which contains nitrogen distributed therein.

19. A magnetic disk apparatus according to

claim 18

, wherein nitrogen is distributed in an inclined concentration in said carbonaceous protective layer, and a nitrogen concentration is gradually increased from a bottom surface side to a top surface side in said carbonaceous protective layer.

20. A magnetic disk apparatus according to

claim 18

, wherein nitrogen is substantially not contained in a lower half portion, occupying a substantially one half of the thickness-wise distance from a bottom surface of said carbonaceous protective layer.