VACUUM ARC EVAPORATION APPARATUS AND METHOD, AND MAGNETIC RECORDING MEDIUM FORMED THEREBY

• US 20110256426A1
• Filed: 06/29/2011
• Published: 10/20/2011
• Est. Priority Date: 07/08/2003
• Status: Active Grant

• Current Assignee: Fuji Electric Company Limited (Fuji Electric Systems Company Limited)
• Original Assignee: Fuji Electric Company Limited (Fuji Electric Systems Company Limited)
• Inventors: NAGATA, Naruhisa
• Granted Patent: US 8,500,967 B2
• Time in Patent Office: Days
• US Class Current: 428/835.2
• CPC Class Codes: H01J 37/32055 Arc discharge
• CPC Class Codes: H01J 37/3266 Magnetic control means

Abstract

In a vacuum arc evaporation apparatus, to stably maintain vacuum arc discharge at an arc source when depositing a cathode material on a substrate, namely a magnetic recording medium, an ungrounded anode of a coil-type tube is placed inside an arc source discharge vacuum chamber. A DC arc power supply is connected between the cathode and the anode to cause an arc current to flow in the anode to generate a first magnetic field in one direction, from the cathode toward the anode. A second magnetic field is generated in the opposite direction, from the anode to the cathode by feeding a specified current to an external coil positioned around the discharge chamber. The external coil includes an around-cathode coil and an around-anode coil. The arc discharge can be started by operating a striker to carry out the deposition.

Claims

1. A method of depositing a film on to a substrate, with a vacuum arc evaporation apparatus comprising:

a deposition vacuum chamber;

a discharge unit having;

an electrically grounded discharge vacuum chamber;

an ungrounded cathode target located in the discharge vacuum chamber;

an ungrounded anode consisting essentially of a first coil provided inside the discharge vacuum chamber to generate a first magnetic field;

a second coil provided along around the discharge vacuum chamber to generate a second magnetic field; and

a striker,

wherein the discharge unit discharges an arc of a cathode material from the cathode target to form a cathode-material plasma; and

a plasma guiding unit disposed between the deposition vacuum chamber and the discharge unit for guiding the cathode-material plasma to the deposition vacuum chamber by an induced magnetic field to deposit the cathode material on to a substrate disposed inside the deposition vacuum chamber,

the method comprising the steps of;

evacuating the deposition vacuum chamber containing the substrate;

generating the second magnetic field by feeding current to the second coil;

starting the arc discharge by contacting the surface of the cathode target with the striker;

generating the cathode-material plasma by arc discharging the cathode target;

generating the first magnetic field by feeding the arc discharge current to the first coil;

depositing the cathode target on the substrate by guiding the cathode-material plasma to the deposition vacuum chamber with the plasma guiding unit,

wherein the first magnetic field extends substantially along a first direction away from the cathode target toward the first coil, and

wherein the second magnetic field extends substantially along a second direction, which is substantially opposite to the first direction, away from the first coil toward the cathode target.

2. The method according to claim 1, wherein:

the first coil is positioned downstream of the cathode target, between the plasma guiding unit and the cathode target, and

the direction of the first magnetic field is substantially parallel with the direction of the discharge vacuum chamber.

3. The method according to claim 1, wherein the second coil comprises a Helmholtz coil pair, one of which surrounds part of the first coil and the other of which surrounds the electrically ungrounded cathode target.

4. The method according to claim 1, wherein:

the current fed to the second coil is DC current, and

the arc discharge current fed to the first coil is DC current.

5. The method according to claim 1, wherein the cathode material is carbon.

6. The method according to claim 1, wherein the substrate has a magnetic recording layer and the cathode material is deposited on the magnetic layer as an overcoat layer.

7. The method according to claim 6, wherein the deposition material is carbon to form the overcoat layer having a tetrahedral amorphous carbon structure with a high hardness.

8. A magnetic recording medium formed by depositing the overcoat layer on the substrate with the magnetic layer according to the method of claim 7.

9. A method of depositing a film on to a substrate, with a vacuum arc evaporation apparatus comprising:

a deposition vacuum chamber;

a discharge unit having;

an electrically grounded discharge vacuum chamber;

an electrically ungrounded cathode target located inside the discharge vacuum chamber, wherein the discharge unit discharges an arc of a cathode material from the electrically ungrounded cathode target to form a cathode-material plasma;

a first field generating unit composed of an electrically ungrounded anode consisting essentially of a first coil provided inside the discharge vacuum chamber for generating a first magnetic field directed in a first direction;

a second field generating unit composed of a second coil provided along around the discharge vacuum chamber for generating a second magnetic field in a second direction, which extends substantially opposite to the first direction; and

a striker; and

a plasma guiding unit disposed between the deposition vacuum chamber and the discharge unit for guiding the cathode-material plasma to the deposition vacuum chamber by an induced magnetic field to deposit the cathode material on to a substrate disposed inside the deposition vacuum chamber,

wherein the electrically ungrounded anode extends along an inner wall of the discharge vacuum chamber and is positioned downstream of the electrically ungrounded cathode target, between the plasma guiding unit and the electrically ungrounded cathode target,

wherein the electrically ungrounded anode in its entirety is positioned downstream of the electrically ungrounded cathode target,

wherein the first coil has a plurality of continuous windings, and the direction of a center axis of the first coil is substantially parallel with the direction from the electrically ungrounded cathode target to the first coil, and

wherein the direction of a center axis of the second coil is substantially parallel with the direction from the electrically ungrounded cathode target to the first coil,

the method comprising the steps of;

evacuating the deposition vacuum chamber containing the substrate;

generating the second magnetic field by supplying current to the second coil so that the second magnetic field extends in the second direction, toward the electrically ungrounded cathode target;

generating the cathode material plasma by arc discharging the cathode target with the striker;

generating the first magnetic field by supplying current to the first coil so that the first magnetic field extends in the first direction, away from the electrically ungrounded cathode target; and

depositing the cathode material on the substrate by guiding the cathode-material plasma to the deposition vacuum chamber with the plasma guiding unit.

10. The method according to claim 9, wherein the second coil comprises a Helmholtz coil pair, one of which surrounds part of the first coil and the other of which surrounds the electrically ungrounded cathode target.

11. The method according to claim 9, wherein:

the current fed to the second coil is DC current, and

the current fed to the first coil is DC current.

12. The method according to claim 9, wherein the cathode material is carbon.

13. The method according to claim 9, wherein the substrate has a magnetic recording layer and the cathode material is deposited on the magnetic layer as an overcoat layer.

14. The method according to claim 13, wherein the cathode material is carbon to form the overcoat layer having a tetrahedral amorphous carbon structure with a high hardness.

15. A magnetic recording medium formed by depositing the overcoat layer on the substrate with the magnetic layer according to the method of claim 14.