Cathode arc source
View Patent ↗A cathode arc source comprises: a cathode target; a first magnetic field source located above the target; a second magnetic field source located below the target; and a third magnetic field source located between the first and second magnetic field sources and having an opposite polarity to the first magnetic field source; wherein the resultant magnetic field from the first, second and third magnetic field sources has zero field strength in a direction substantially normal to the target at a position above the target. The invention also provides methods of striking a cathode target and methods of depositing coatings which can be carried out using the cathode arc source described herein.
1. A cathode arc source comprising:
a station for a cathode target;
a first magnetic field source located between the target station and the position where a substrate is to be located;
a second magnetic field source located below the target station; and
a third magnetic field source located between the first and second magnetic field sources and having an opposite polarity to the first magnetic field source;
characterised in that the resultant magnetic field from the first, second and third magnetic field sources has zero field strength in a direction substantially normal to the target station at a position of up to 10 cm above the target, and wherein the second magnetic field source has an opposite polarity to the first magnetic field source.
2. A cathode arc source according to claim 1 wherein the resultant magnetic field from the first, second and third magnetic field sources has zero field strength in a direction substantially normal to the target station at a position of up to 8 cm above the target.
3. A cathode arc source according to claim 1 wherein the first, second and/or third magnetic field sources are magnetic field generating coils.
4. A cathode arc source according to claim 1 wherein the strength of at least one of the first, second and third magnetic field sources are adjustable.
5. A cathode arc source according to claim 4 wherein the strengths of at least two of the first, second and third magnetic field sources are adjustable.
6. A cathode arc source according to claim 1 wherein the strength of the first, second and third magnetic field sources are all adjustable.
7. A cathode arc source according to claim 1 wherein the first and third magnetic field sources are magnetic field generating coils and the second magnetic field source is a permanent magnet.
8. A cathode arc source according to claim 1 wherein the distances of at least one of the first, second and third magnetic field sources either above or below the target are adjustable.
9. A cathode arc source according to claim 8 wherein the distances of at least two of the first, second and third magnetic field sources either above or below the target are adjustable.
10. A cathode arc source according to claim 1 wherein the distances of the first, second and third magnetic field sources above or below the target are all adjustable.
11. A cathode arc source according to claim 1 , comprising a carbon target.
12. A cathode arc source according to claim 1 , comprising a metal target or an alloy target.
13. A method of depositing a coating on a substrate, comprising generating positive ions from a target in a cathode vacuum arc source according to claim 1 , and depositing the ions onto the substrate, wherein the target is a metal other than aluminum, chromium or titanium.
14. A method according to claim 13 , wherein the target comprises copper or nickel.
15. A method according to claim 13 , wherein the coating is deposited using a cathode arc source according to claim 1 .
16. A cathode arc source according to claim 1 , wherein the target has a diameter of from 5 cm to 15 cm.
17. A cathode arc source according to claim 1 , wherein the resultant magnetic field is such that:
(1) at a front surface of the target, the resultant field direction substantially normal to the front surface is towards the front surface;
(2) magnetic field strength in the direction substantially normal to the front surface decreases with increasing distance from the target to a point or region of zero normal field strength; and
(3) from the point or region of zero normal field strength, with increasing distance from the target, field direction is away from the front surface of the target.