ANODE FOR PVD PROCESSES

Abstract

The invention relates to the proposal of an electrode arrangement in a device for carrying out processes of physical vapor deposition that greatly reduces or even prevents the degradation of the electrode material caused by accretions. The contamination of the anode occurring in these processes due to cathodic carbon is minimized or prevented by the application of a thin adhesion-reducing coating of high electrical conductivity to the anode, which coating has poorer adhesive properties with regard to the coating material than the uncoated anode material. This coating is preferably a nitride coating, particularly preferably of TiN, applied with a coating thickness of between 0.1 μm and 3.5 μm.

Claims

1. An anode, suitable for processes of physical vapor deposition, wherein the surface of the anode is completely or partially covered with an adhesion-reducing thin coating of high electrical conductivity.

2. A device for processes of physical vapor deposition with an anode arrangement, comprising: a vessel for enclosing different process pressures, in the interior of which at least two electrodes subjectable to an electrical voltage from outside the vessel are arranged, wherein at least one of the electrodes acts as an anode and at least one of the electrodes acts as a cathode, and an arc discharge is generatable between the cathode and the anode and maintained over a defined period of time, wherein at least one of the anodes comprises an adhesion-reducing thin coating of high electrical conductivity which completely or partially covers the surface of the electrode.

3. The device according to claim 1, wherein the anode comprises a hot anode, and the thin coating of high electrical conductivity is suitable for high anode temperatures.

4. The device according to claim 1, wherein the thin adhesion-reducing coating has a thickness of between 0.1 μm and 3.5 μm.

5. The device according to claim 4, wherein the thin adhesion-reducing coating is a ceramic nitride coating.

6. The device according to claim 5, wherein the material of the ceramic nitride coating is a metal nitride selected from the metals Ti, Zr, Hf and V or a mixture of these.

7. The device according to claim 6, wherein the selected metal nitride has a specific electrical resistance of between 10 μcm and 150 μcm.

8. The device according to claim 7, wherein the cathode consists entirely of an electrically conductive carbon modification or comprises an electrically conductive carbon modification at least partially on its surface.

9. The device according to claim 8, wherein the electrically conductive carbon modification is graphite.

10. The device according to claim 2, wherein a distance between the electrodes is adjustable with at least one of the electrodes being designed to be movable.

11. The device according to claim 2, wherein at least one of the electrodes is configured to be exchangeable.

12. The device of claim 2, wherein the device is usable as a coating installation for coating substrates applied to a mount.

13. A method for producing an anode, for process of physical vapor deposition, wherein the surface of the anode is completely or partially covered with an adhesion-reducing thin coating of high electrical conductivity, the method comprising: polishing and coating the anode, wherein the electrode is polished before the thin coating is applied until the value of an average roughness of the polished surface reaches between 0.01 μm and 0.3 μm, wherein, subsequently, the thin coating is applied and the thin coating is left as is or polished until the value of the average roughness of the polished thin coating surface reaches a value of greater than 0.01 μm and less than 0.1 82 m; and using the anode as an electrode in a device comprising: a vessel for enclosing different process pressures, in the interior of which at least two electrodes subjectable to an electrical voltage from outside the vessel are arranged, wherein at least one of the electrodes acts as the anode and at least one of the electrodes acts as a cathode, and an arc discharge is generatable between the cathode and anode and maintained over a defined period of time, wherein at least one of the anodes comprises an adhesion-reducing thin coating of high electrical conductivity which completely or partially covers the surface of the electrode.

14. The method according to claim 13, wherein the method steps “polishing” and “coating” are carried out a plurality of times.

15. The method according to claim 14, wherein the method steps “polishing” and “coating” are repeated in any order after having been carried out once.

Description

[0046] The invention is described below in a plurality of embodiments and illustrated in the associated figures.

[0047] FIG. 1 is a schematic illustration that shows, as a first embodiment, the cross section of an anode (614) coated with an adhesion-reducing thin coating of high electrical conductivity. The adhesion-reducing thin coating of high electrical conductivity is, in this case, partially applied to the core material of the anode (601) with a preferred coating thickness of 0.1 μm to 3.5 μm (624). In this example, the anode is not coated in the region where the anode is fitted into an electrode mount with a blind hole-shaped recess (604).

[0048] FIG. 2 is a schematic illustration that shows, as a second embodiment, the cross section of an anode (614) completely coated with an adhesion-reducing thin coating of high electrical conductivity, which, for example, is mounted at the end (605) and is electrically connected in a conductive manner.

[0049] In one embodiment, a graphite cathode and an anode are arranged in a vacuum chamber provided with a sensor system for monitoring the process conditions and a pumping station.

[0050] The vacuum chamber is additionally provided with an opening which can be closed in a gas-tight, in particular vacuum-tight, manner. In the interior of the vacuum chamber there is a mount for the application of the substrates intended for coating. The mount itself is configured to be electrically insulating with respect to the process chamber wall and electrically insulating with respect to the substrate. The substrates are connected as auxiliary anodes after they have made electrical contact over the course of the process.

[0051] Beforehand, with the opening of the vacuum chamber wall sealed in a gas-tight manner, the process pressure in the vacuum chamber is set to approx. 10.sup.−6 hPa by means of the connected pumping station. An electrical voltage of approx. 200 V is set between the main electrodes.

[0052] The laser of the ignition device generates a beam spot of pulsed laser light on the surface of the graphite cathode over a period of approximately 50 ns. This generates carbon ions and electrons, and the electric arc ignites for a period of approx. 330 μs. After this time has elapsed, a new pulse of the beam spot is generated from laser light at a location that is not identical to the previous location. Using this procedure, the entire cathode surface is scanned.

[0053] The anode used is coated with an adhesion-reducing and electrically conductive nitride coating of TiN. The coating thickness of the coating used is approx. 2 μm.

[0054] In order to apply the thin coating of high electrical conductivity to the anode surface, said surface is mechanically polished beforehand. The mechanical polishing or lapping of the anode surface is carried out according to the following steps until the mirror finish is achieved: [0055] 1. preparation of the uncoated anode by sanding said anode with an abrasive having a grain size between 80-120, [0056] 2. removal of rough scratches by sanding with a “medium” grain size 180-220, [0057] 3. pre-polishing with a polishing disc having a grain size of 280-320 and [0058] 4. polishing with a suitable polishing paste and a suitable polishing disc.

[0059] The grain sizes of the above-mentioned polishing and abrasive materials refer to the classification according to the FEPA standard.

LIST OF REFERENCE SIGNS

[0060] 601 Anode [0061] 604 Electrode mount as a blind hole-shaped recess [0062] 605 Electrode mount as a front mount [0063] 614 Partly coated anode [0064] 624 Fully coated anode