Recording media having protective overcoats of highly tetrahedral amorphous carbon and methods for their production

• US 20030148103A1
• Filed: 01/23/2003
• Published: 08/07/2003
• Est. Priority Date: 05/31/1996
• Status: Active Grant

• Current Assignee: Diamondop LLC
• Original Assignee: United Modular Corporation
• Inventors: Li, Eric, Weiler, Manfred, Vijayen, Veerasamy
• Granted Patent: US 6,805,891 B2
• Time in Patent Office: Days
• US Class Current: 428/408
• CPC Class Codes: C03C 17/22 with other inorganic material C03C17/34, C03C17/44 take precedence
• CPC Class Codes: C03C 2217/282 Carbides, silicides
• CPC Class Codes: C03C 2218/151 by vacuum evaporation
• CPC Class Codes: C23C 16/26 Deposition of carbon only
• CPC Class Codes: C23C 16/486 using ion beam radiation
• 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 2237/0815 Methods of ionisation
• CPC Class Codes: H01J 27/18 with an applied axial magnetic field
• CPC Class Codes: H01J 37/08 Ion sources; Ion guns
• CPC Class Codes: H01J 37/32091 the radio frequency energy being capacitively coupled to the plasma
• CPC Class Codes: H01J 37/32357 Generation remote from the workpiece, e.g. down-stream
• CPC Class Codes: Y10T 428/1164 with protective film
• CPC Class Codes: Y10T 428/24355 Continuous and nonuniform or irregular surface on layer or component [e.g., roofing, etc.]
• CPC Class Codes: Y10T 428/265 1 mil or less
• CPC Class Codes: Y10T 428/30 Self-sustaining carbon mass or layer with impregnant or other layer
• CPC Class Codes: Y10T 428/31678 Of metal

Abstract

The invention provides systems and methods for the deposition of an improved diamond-like carbon material, particularly for the production of magnetic recording media. The diamond-like carbon material of the present invention is highly tetrahedral, that is, it features a large number of the sp³ carbon-carbon bonds which are found within a diamond crystal lattice. The material is also amorphous, providing a combination of short-range order with long-range disorder, and can be deposited as films which are ultrasmooth and continuous at thicknesses substantially lower than known amorphous carbon coating materials. The carbon protective coatings of the present invention will often be hydrogenated. In a preferred method for depositing of these materials, capacitive coupling forms a highly uniform, selectively energized stream of ions from a dense, inductively ionized plasma. Such inductive ionization is enhanced by a relatively slow moving (or “quasi-static”) magnetic field, which promotes resonant ionization and ion beam homogenization.

Claims

1. Magnetic recording media comprising:

.

a substrate;

a magnetic layer disposed over the substrate; and

a protective layer disposed over the magnetic layer, the protective layer comprising a highly tetrahedral amorphous carbon.

2. A recording media as in claim 1, wherein the highly tetrahedral amorphous carbon of the protective layer includes more than about 35% sp³ carbon-carbon bonds.

3. A recording media as in claim 1, wherein the highly tetrahedral amorphous carbon of the protective layer includes more than about 70% sp³ carbon-carbon bonds.

4. A recording media as in claim 1, wherein the sp³ carbon-carbon bonds are at least in part formed by directing an energized stream of carbon ions toward the substrate.

5. A recording media as in claim 1, wherein the density of the protective layer is more than 2.5 g/cm³.

6. A recording media as in claim 1, wherein the highly tetrahedral amorphous carbon of the protective layer does not include macroparticles.

7. A recording media as in claim 1, wherein the protective layer has a hardness of over about 50 GPa.

8. A recording media as in claim 1, wherein the protective layer has a thickness of less than about 75 A.

9. A recording media as in claim 1, wherein the highly tetrahedral amorphous carbon of the protective layer further comprises hydrogen.

10. A recording media as in claim 9, wherein the protective layer comprises between about 8 and 18 atomic percent hydrogen.

11. A recording media as in claim 1, wherein the highly tetrahedral amorphous carbon of the protective layer further comprises nitrogen.

12. A recording media as in claim 11, wherein the protective layer comprises between about 4 and 30 atomic percent nitrogen.

13. A method for enhancing an ion beam, the ion beam produced by inductively ionizing a plasma within a plasma volume and capacitatively coupling the plasma so as to form a stream of ions from within the plasma volume, the method comprising:

moving a magnetic field through the plasma volume to promote even resonant inductive ionization and homogenize the ion beam.

14. A method as claimed in claim 13, wherein moving the magnetic field comprises selectively energizing magnetic coils disposed about the plasma volume.

15. A method as claimed in claim 13, wherein the magnetic field rotates through the plasma volume with a frequency which is much less than the frequency of an alternating induction potential.

16. A method as claimed in claim 13, wherein the magnetic field is transverse and rotates about an axis which is substantially normal to a capacitatively coupled extraction grid.

17. A method as claimed in claim 13, wherein the magnetic field rotates with a frequency of less than 10,000 Hz.

18. An inductive ionization resonance system for use with an ion-beam source including an antenna disposed about a plasma volume for inductively ionizing a plasma therein, a coupling electrode exposed to the plasma volume, and an extraction electrode disposed over an opening of the plasma volume so that the extraction electrode is capable of extracting a stream of ions of the plasma therethrough by capacitive coupling, the system comprising at least one coil disposed adjacent the plasma volume, the at least one coil capable of moving a transverse magnetic field through the plasma volume to homogenize the stream of ions.

19. A system as claimed in claim 18, further comprising a plurality of coils disposed about the container so that the magnetic field can be moved within the plasma volume by selectively energizing one or more coils.

20. A system as claimed in claim 19, wherein the plurality of coils are radially disposed about the axis.

21. A system as claimed in claim 18, wherein the plasma volume substantially defines a length and a diameter, wherein the opening is disposed at one end of the length, and wherein the length is between about one third the diameter and three times the diameter.

22. Magnetic recording media comprising:

a substrate;

a magnetic layer disposed over the substrate; and

a protective layer disposed over the magnetic layer, the protective layer comprising a highly tetrahedral amorphous carbon having a density of more than 2.5 g/cm³.