Title of Invention	A VACUUM PROCESS FOR ETCHING A METAL STRIP AND AN INSTALLATION THEREFOR
Abstract	Vacuum process and installation for etching a metal strip by magnetron sputtering Abstract The invention relates to a vacuum process of etching a metal strip (2) running above at least one counterelectrode (3, 3') made of conductive material by magnetron sputtering in a vacuum chamber (1) in which a plasma is created in a gas close to said metal strip (2) so as to generate radicals and/or ions that act on this metal strip (2), a magnetic confinement circuit (4) being placed above said metal strip (2) , characterized in that said counterelectrode {3, 3') has a surface that can move, by rotation and/or by translation, relative to said metal strip (2) , said surface being set in motion during the etching and being continuously cleaned by a cleaning device (5, 5') placed in the shadow of said plasma before again being exposed to said plasma. The invention also relates to an etching installation for implementing the process. Figure 1

Title of Invention

A VACUUM PROCESS FOR ETCHING A METAL STRIP AND AN INSTALLATION THEREFOR

Abstract

Vacuum process and installation for etching a metal strip by magnetron sputtering Abstract The invention relates to a vacuum process of etching a metal strip (2) running above at least one counterelectrode (3, 3') made of conductive material by magnetron sputtering in a vacuum chamber (1) in which a plasma is created in a gas close to said metal strip (2) so as to generate radicals and/or ions that act on this metal strip (2), a magnetic confinement circuit (4) being placed above said metal strip (2) , characterized in that said counterelectrode {3, 3') has a surface that can move, by rotation and/or by translation, relative to said metal strip (2) , said surface being set in motion during the etching and being continuously cleaned by a cleaning device (5, 5') placed in the shadow of said plasma before again being exposed to said plasma. The invention also relates to an etching installation for implementing the process. Figure 1

Full Text	Vacuum process and installation for etching a metal strip by magnetron sputtering The present invention relates to a vacuum process and installation for etching a metal strip, such as for example a steel strip, by magnetron sputtering. During operations of vacuum coating a steel strip, the state of cleanliness of the strip before deposition is one of the key success factors, as it determines the good adhesion of the coating to be deposited. One of the processes used to do this is vacuum etching by magnetron sputtering, also called sputter etching. This process consists in creating, between the strip and a counterelectrode, a plasma in a gas that makes it possible to generate radicals and/or ions. These ions are, under normal operating conditions, accelerated toward the surface of the strip to be etched and tear off surface atoms, thus cleaning the possibly soiled surface, while activating it. The strip to be etched runs through a vacuum chamber facing a counterelectrode. The latter is positively biased with respect to the metal strip, which is itself preferably grounded. An array of magnets positioned behind the strip confines the plasma created close to it. For very precise positioning of the metal strip to be treated, with respect to the counterelectrode needed for implementing the magnetron sputtering, the metal strip is generally placed on a backing roll that can be rotated about its axis. However, this type of roll is not needed when metal strip in the form of rigid plates is treated. However, the problem that arises when applying this technique for cleaning a continuously running metal strip, such as a steel strip, is the fouling of the particles eroded from the surface of the strip are deposited on the facing parts, that is to say on the counterelectrode, and with time cover it with a weakly bonded black film. This ends up being cracked and peeling off, forming pulverulent chips that initiate arcs. The formation of arcs may cause: ■ - firstly, damage to the surface of the steel strip at the point where the arc is initiated; and - secondly, an etching defect on a small area of the running strip owing to the break of short duration (about 100 \xs) in the supply of current by the generator upon detection of the arc. Finally, when the deposit is a dielectric, it may isolate the electrode and impede the operation of the plasma. It therefore proves to be essential to maintain a good state of cleanliness of the counterelectrode during the etching process. Document EP-A-0 908 535 discloses a process for etching the surface of a metal strip contaminated by a thin oxide film. The counterelectrodes employed are used in pairs connected to an AC current generator.,They have a flat or rounded shape and make it possible to prevent the formation of arcs over a certain period of time. After a certain period of time- in service, these electrodes become fouled, which means that the process has to be interrupted, in order to clean said electrodes, or else the etching power has to be reduced'. In all cases this impairs its efficiency and/or its quality. ■ The obj ect of the present invention is therefore to remedy the drawbacks of the processes of the prior art by providing a vacuum process and installation for etching the surface of a running metal strip by magnetron sputtering, ■ which makes it possible to improve the quality and the efficiency of the etching, while preventing any damage to the metal strip and any etching defect due to the inopportune formation of electric arcs, and to do so without the process being interrupted. For this purpose, the first subject of the invention is a vacuum process for etching a metal strip running above at least one counterelectrode made of conductive material by magnetron sputtering in a vacuum chamber, in which a plasma is created in a gas close to said metal strip so as to generate radicals and/or ions that act on this metal strip, a magnetic confinement circuit being placed above the metal strip, in . which counterelectrode has a surface that can move, by rotation and/or by translation, relative to the metal ■ -strip, the surface being set in motion during the etching and being continuously cleaned by a cleaning device placed in the shadow of the plasma before again being exposed to the plasma. The process according to the invention may furthermore include the following features, taken in isolation or in combination: - the cleaning device is a cleaning device having a localized mechanical action; - the cleaning device consists of a rigid scraper in contact with the moving surface of the counterelectrode; - the matter scraped off the moving surface of the counterelectrode by the action of the cleaning device is recovered by a collecting device placed on the bottom of said vacuum chamber; - the counterelectrode is positively biased relative to the metal strip, it being possible for the metal strip to be grounded or not; - the counterelectrode is subjected to an AC potential, it being possible for the metal strip to be grounded or not; - the vacuum chamber is provided with a counterelectrode consisting of at least two rotating rolls and a tensioned belt on the rolls; and - the counterelectrode or counter electrodes are cooled. The second subject of the invention consists of a vacuum installation for etching a metal strip by magnetron sputtering, comprising a vacuum chamber in which there are at least one counterelectrode, means for biasing the metal strip, means for biasing the counterelectrode, means for creating a plasma in a gas between the metal strip and the counterelectrode, at least one magnetic confinement circuit being placed above the metal strip and the Counterelectrode having a surface that can move, by rotation and/or by translation, relative to the metal strip, and a cleaning device for cleaning the moving surface, which is placed in the shadow of the plasma. The installation according to the invention may furthermore incorporate the following features, taken in isolation or in combination: - the cleaning device is a cleaning device having a localized mechanical action; - the cleaning device consists of a rigid scraper in contact with the moving surface of the counterelectrode; - the vacuum chamber further includes a collecting device for collecting the matter scraped off the moving surface of the counterelectrode via the action of said cleaning device, the collecting device being placed on the bottom of said vacuum chamber; - the counterelectrode is positively biased relative to the metal strip, it being possible for said metal strip to be grounded or not; - the counterelectrode is subjected to an AC potential, it being possible for the metal strip to be grounded or not; - the vacuum chamber is provided with a counterelectrode consisting of at least two rotating rolls and a tensioned belt on the rolls; and - the counterelectrode is provided with cooling means. The invention will now be described in greater detail with reference to the appended figures, which represent: - figure 1: a sectional schematic view of one embodiment of an installation according to the invention; - figure 2: a sectional schematic view of a second embodiment of an installation according to the. invention; and - figure -3-: a sectional schematic view of a third embodiment of an installation according to the invention. Considering firstly figure 1, this shows a vacuum chamber 1 through which runs a metal strip 2, such as a steel strip. In the bottom part of this vacuum chamber 1 there are two counterelectrodes 3 and 3' of cylindrical shape which can be rotated about their . axes. The counterelectrodes 3, 3' must be made of conductive material. Although a ferromagnetic material may be suitable, it is recommended to use a no ferromagnetic material so as not to disturb the magnetic confinement of the plasma. The counterelectrodes 3, 3' heat up, so that in certain cases they have to be cooled. They , are rotated, for example mechanically by the metal strip 2 running over them. The counterelectrodes 3, 3' may also be driven by an electric motor placed under vacuum, a pneumatic motor, a hydraulic motor, or via a rotary vacuum seal. The metal strip 2 is grounded, whereas the counterelectrodes 3, 3' are positively biased. Above, this strip 2 there is a magnetic circuit 4 taking the form of magnets that serve to confine the plasma close to the metal strip 2. Each counterelectrode 3, 3' is provided with a scraper 5, 5', each scraper being placed in the shadow of the plasma for etching the metal strip 2. Particular care must be taken when fastening the scrapers 5, 5' so as to avoid creating a short circuit between the counterelectrodes 3, 3' and the other components of the system, even after the internal surfaces of the cell have been plated with the etched-off conductive particles. Ant plating baffles may be placed around the isolators. These baffles are located between the wall of ■ the chamber 1 and the scrapers' 5, 5' so as to mutually isolate them. The support for the scrapers 5, 5' is thus not plated, thereby preventing any short circuit. The scrapers 5, 5' may be made of any suitable material provided that it is not a conductor. In particular, they may be ceramic or glass. Precautions may also be taken to ensure that the scrapers 5, 5' do not blast chips toward the metal strip 2, even after rebounding. The vacuum chamber 1 also includes a tray 6 for recovering the matter scraped off by the scrapers 5, 5' When the metal strip 2 has been etched in the vacuum chamber 1, the counterelectrodes 3, 3' are made to undergo a relatively slow rotational movement so that they are continuously cleaned by means of the scrapers 5, 5'. The matter scraped off by these means drops into the tray 6, which may be periodically emptied. Now considering figure 2, this shows a second embodiment of the invention in which an AC potential is applied to the counterelectrodes 3, 3', the running metal strip 2 being grounded or not. The system may comprise one or more counterelectrodes. As may be seen in the partial view shown in figure 4, the counterelectrode 7 may also consist of a belt 8 tensioned between two rolls 9, 9' and driven using the "conveyor belt" principle. A scraper 10 placed in the shadow of the plasma is used to clean the belt while it is running in the vacuum chamber 1. Illustrative example One indicator of the efficiency of an etching system may be the maximum power that can be applied to the etching cell without arc formation. A trial was therefore carried out in which this maximum power was measured for a conventional etching cell and for an etching cell as shown in figure 1. Thus, it has been demonstrated that the maximum steady power measured for an etching installation according to the invention is more than twice that for a conventional installation having a flat stationary counterelectrode. Since the rate of erosion of a metal strip by magnetron etching varies with the applied power, the use of the counterelectrodes according to the invention enables the efficiency of etching to be doubled. The counterelectrode system presented above remains clean over the course of time and prevents the appearance of arcs starting from particles emanating from the etching of the metal strip surface or the "disappearing anode" problem. CLAIMS 1. A vacuum process for etching a metal strip (2) running above at least one counterelectrode (3, 3' , 7) made of conductive material by magnetron sputtering in a vacuum chamber (1) , in which a plasma is created in a gas close to said metal strip {2) so as to generate radicals and/or ions that act on this metal strip (2) , a magnetic confinement circuit (4) being placed above said metal strip (2), characterized in that said counterelectrode (3, 3', 7) has a surface that can move, by rotation and/or by translation, relative to said metal strip {2), said surface being set in motion during the etching and being continuously cleaned by a cleaning device (5, 5', 10) placed in the shadow of said plasma, before again being exposed to said plasma. 2. The etching process as claimed in claim 1, in which said cleaning device (5, 5', 10) is a cleaning device having a localized mechanical action. 3- The etching process as claimed in claim 2, in which said cleaning device (5, 5', 10) consists of a rigid scraper in contact with the moving surface of said counterelectrode (3, 3', 7). 4. The etching process as claimed in any one of claims 1 to 3, in which the matter scraped off the moving surface of said counterelectrode (3, 3', 7) by the action of said cleaning device (5, 5', 10) is recovered by a collecting device (6) placed on the bottom of said vacuum chamber (1). ■5. The etching process as claimed in any one of claims 1 to 4, in which said counterelectrode (3, , 3', 7) is positively biased relative to the metal strip (2), it being possible for said metal strip (2) to be grounded or not. 6. The etching process as claimed in any one of claims 1 to 4, in which said counterelectrode (3, 3' , 7) is subjected to an AC potential, it being possible for the metal strip (2) to be grounded or not. 7. The process as claimed in any one of claims 1 to 6, in which the vacuum chamber (1) is provided with a counterelectrode (7) consisting of at least two rotating rolls (9, 9') and a tensioned belt (8) on said rolls (9, 9'). 8. The process as claimed in any one of claims 1 to If in which said counterelectrode (3, 3' , 7) is cooled. 9. The process as claimed in any one of claims 1 to 8, in which said metal strip (2) is a steel strip. 10. A vacuum installation for etching a metal strip (2) by magnetron sputtering, comprising a vacuum chamber (1) in which there are at least one counterelectrode (3, 3', 7), means for biasing said metal strip, means for biasing said counterelectrode (3, 3', 7), means for creating a plasma in a gas between said metal strip {2) and I said counterelectrode {3, 3', 1) , at least one magnetic confinement circuit •( 4) being placed above said metal strip [2) and said counterelectrode (3, 3', 7) having a surface that can move, by rotation and/or by translation, i relative to said metal strip (2), and a cleaning device (5, 5', 10) for cleaning said moving surface, which is placed in the shadow of said plasma. 11. The etching installation as claimed in claim 10, in which said cleaning device (5, 5' , 10) is a cleaning device having a localized mechanical action. 12. The etching installation as claimed in claim 11, in which said cleaning device (5, 5' , 10) consists of a rigid scraper in contact with the moving surface of said counterelectrode (3, 3', 7). 13. The etching installation as claimed in any one of claims 10 to 12, in which the vacuum chamber (1) further includes a collecting device (6) for collecting the matter scraped off the moving surface of said counterelectrode (3, 3', 7) via the action of said cleaning device (5, 5', 10), said collecting device (6) being placed on the bottom of said vacuum chamber (1) . 14. The etching installation as claimed in any one of claims 10 to 13, in which said counterelectrode (3, 3', 7) is positively biased relative to the metal strip (2), it being possible for said metal strip (2) to be grounded or not. 15. The etching installation as claimed in any one of claims 10 to 13, in which said counterelectrode (3, 3', 7) is subjected to an AC potential, it being possible for the metal strip (2) to be grounded or not. 16. The installation as claimed in any one of claims 10 to 15, in which the vacuum chamber (1) is ■provided with a counterelectrode (7) consisting of at least two rotating rolls (9, 9') and a tensioned belt (8) on said rolls {9, 9'). 17. The installation as claimed in any one of claims 10 to 16, in which said counterelectrode (3, 3', 7} is provided with cooling means.

Full Text

Vacuum process and installation for etching a metal strip by magnetron sputtering
The present invention relates to a vacuum process and installation for etching a metal strip, such as for example a steel strip, by magnetron sputtering.
During operations of vacuum coating a steel strip, the state of cleanliness of the strip before deposition is one of the key success factors, as it determines the good adhesion of the coating to be deposited. One of the processes used to do this is vacuum etching by magnetron sputtering, also called sputter etching. This process consists in creating, between the strip and a counterelectrode, a plasma in a gas that makes it possible to generate radicals and/or ions. These ions are, under normal operating conditions, accelerated toward the surface of the strip to be etched and tear off surface atoms, thus cleaning the possibly soiled surface, while activating it.
The strip to be etched runs through a vacuum chamber facing a counterelectrode. The latter is positively biased with respect to the metal strip, which is itself preferably grounded. An array of magnets positioned behind the strip confines the plasma created close to it. For very precise positioning of the metal strip to be treated, with respect to the counterelectrode needed for implementing the magnetron sputtering, the metal strip is generally placed on a backing roll that can be rotated about its axis. However, this type of roll is not needed when metal strip in the form of rigid plates is treated.
However, the problem that arises when applying this technique for cleaning a continuously running metal strip, such as a steel strip, is the fouling of the

particles eroded from the surface of the strip are deposited on the facing parts, that is to say on the counterelectrode, and with time cover it with a weakly bonded black film. This ends up being cracked and peeling off, forming pulverulent chips that initiate arcs. The formation of arcs may cause: ■
- firstly, damage to the surface of the steel strip at the point where the arc is initiated; and
- secondly, an etching defect on a small area of the running strip owing to the break of short duration (about 100 \xs) in the supply of current by the generator upon detection of the arc.
Finally, when the deposit is a dielectric, it may isolate the electrode and impede the operation of the plasma.
It therefore proves to be essential to maintain a good state of cleanliness of the counterelectrode during the etching process.
Document EP-A-0 908 535 discloses a process for etching the surface of a metal strip contaminated by a thin oxide film. The counterelectrodes employed are used in pairs connected to an AC current generator.,They have a flat or rounded shape and make it possible to prevent the formation of arcs over a certain period of time. After a certain period of time- in service, these electrodes become fouled, which means that the process has to be interrupted, in order to clean said electrodes, or else the etching power has to be reduced'. In all cases this impairs its efficiency and/or its quality.
■ The obj ect of the present invention is therefore to remedy the drawbacks of the processes of the prior art by providing a vacuum process and installation for etching the surface of a running metal strip by magnetron sputtering, ■ which makes it possible to
improve the quality and the efficiency of the etching, while preventing any damage to the metal strip and any etching defect due to the inopportune formation of electric arcs, and to do so without the process being interrupted.
For this purpose, the first subject of the invention is a vacuum process for etching a metal strip running above at least one counterelectrode made of conductive
material by magnetron sputtering in a vacuum chamber, in which a plasma is created in a gas close to said metal strip so as to generate radicals and/or ions that act on this metal strip, a magnetic confinement circuit being placed above the metal strip, in . which
counterelectrode has a surface that can move, by rotation and/or by translation, relative to the metal ■ -strip, the surface being set in motion during the etching and being continuously cleaned by a cleaning device placed in the shadow of the plasma before again
being exposed to the plasma.
The process according to the invention may furthermore include the following features, taken in isolation or in combination:
- the cleaning device is a cleaning device having a localized mechanical action;
- the cleaning device consists of a rigid scraper in contact with the moving surface of the counterelectrode;
- the matter scraped off the moving surface of the counterelectrode by the action of the cleaning device is recovered by a collecting device placed on the bottom of said vacuum chamber;
- the counterelectrode is positively biased relative to the metal strip, it being possible for the metal strip to be grounded or not;
- the counterelectrode is subjected to an AC potential, it being possible for the metal strip to be grounded or not;

- the vacuum chamber is provided with a counterelectrode consisting of at least two rotating rolls and a tensioned belt on the rolls; and
- the counterelectrode or counter electrodes are cooled.
The second subject of the invention consists of a vacuum installation for etching a metal strip by magnetron sputtering, comprising a vacuum chamber in which there are at least one counterelectrode, means for biasing the metal strip, means for biasing the counterelectrode, means for creating a plasma in a gas between the metal strip and the counterelectrode, at least one magnetic confinement circuit being placed above the metal strip and the Counterelectrode having a surface that can move, by rotation and/or by translation, relative to the metal strip, and a cleaning device for cleaning the moving surface, which is placed in the shadow of the plasma.
The installation according to the invention may furthermore incorporate the following features, taken in isolation or in combination:
- the cleaning device is a cleaning device having a localized mechanical action;
- the cleaning device consists of a rigid scraper in contact with the moving surface of the counterelectrode;
- the vacuum chamber further includes a collecting device for collecting the matter scraped off the moving surface of the counterelectrode via the action of said cleaning device, the collecting device being placed on the bottom of said vacuum chamber;
- the counterelectrode is positively biased relative to the metal strip, it being possible for said metal strip to be grounded or not;
- the counterelectrode is subjected to an AC potential, it being possible for the metal strip to be grounded or not;

- the vacuum chamber is provided with a
counterelectrode consisting of at least two rotating
rolls and a tensioned belt on the rolls; and
- the counterelectrode is provided with cooling
means.
The invention will now be described in greater detail with reference to the appended figures, which represent: - figure 1: a sectional schematic view of one embodiment of an installation according to the invention;
- figure 2: a sectional schematic view of a second embodiment of an installation according to the. invention; and
- figure -3-: a sectional schematic view of a third embodiment of an installation according to the invention.
Considering firstly figure 1, this shows a vacuum chamber 1 through which runs a metal strip 2, such as a steel strip. In the bottom part of this vacuum chamber 1 there are two counterelectrodes 3 and 3' of cylindrical shape which can be rotated about their . axes. The counterelectrodes 3, 3' must be made of conductive material. Although a ferromagnetic material may be suitable, it is recommended to use a no ferromagnetic material so as not to disturb the magnetic confinement of the plasma.
The counterelectrodes 3, 3' heat up, so that in certain cases they have to be cooled. They , are rotated, for example mechanically by the metal strip 2 running over them. The counterelectrodes 3, 3' may also be driven by an electric motor placed under vacuum, a pneumatic motor, a hydraulic motor, or via a rotary vacuum seal.
The metal strip 2 is grounded, whereas the counterelectrodes 3, 3' are positively biased.

Above, this strip 2 there is a magnetic circuit 4 taking the form of magnets that serve to confine the plasma close to the metal strip 2.
Each counterelectrode 3, 3' is provided with a scraper 5, 5', each scraper being placed in the shadow of the plasma for etching the metal strip 2. Particular care must be taken when fastening the scrapers 5, 5' so as to avoid creating a short circuit between the counterelectrodes 3, 3' and the other components of the system, even after the internal surfaces of the cell have been plated with the etched-off conductive particles. Ant plating baffles may be placed around the isolators. These baffles are located between the wall of ■ the chamber 1 and the scrapers' 5, 5' so as to mutually isolate them. The support for the scrapers 5, 5' is thus not plated, thereby preventing any short circuit.
The scrapers 5, 5' may be made of any suitable material provided that it is not a conductor. In particular, they may be ceramic or glass.
Precautions may also be taken to ensure that the scrapers 5, 5' do not blast chips toward the metal strip 2, even after rebounding.
The vacuum chamber 1 also includes a tray 6 for recovering the matter scraped off by the scrapers 5, 5'
When the metal strip 2 has been etched in the vacuum chamber 1, the counterelectrodes 3, 3' are made to undergo a relatively slow rotational movement so that they are continuously cleaned by means of the scrapers 5, 5'. The matter scraped off by these means drops into the tray 6, which may be periodically emptied.

Now considering figure 2, this shows a second embodiment of the invention in which an AC potential is applied to the counterelectrodes 3, 3', the running metal strip 2 being grounded or not.
The system may comprise one or more counterelectrodes. As may be seen in the partial view shown in figure 4, the counterelectrode 7 may also consist of a belt 8 tensioned between two rolls 9, 9' and driven using the "conveyor belt" principle. A scraper 10 placed in the shadow of the plasma is used to clean the belt while it is running in the vacuum chamber 1.
Illustrative example
One indicator of the efficiency of an etching system may be the maximum power that can be applied to the etching cell without arc formation.
A trial was therefore carried out in which this maximum power was measured for a conventional etching cell and for an etching cell as shown in figure 1.
Thus, it has been demonstrated that the maximum steady power measured for an etching installation according to the invention is more than twice that for a conventional installation having a flat stationary counterelectrode.
Since the rate of erosion of a metal strip by magnetron etching varies with the applied power, the use of the counterelectrodes according to the invention enables the efficiency of etching to be doubled.
The counterelectrode system presented above remains clean over the course of time and prevents the appearance of arcs starting from particles emanating from the etching of the metal strip surface or the "disappearing anode" problem.

CLAIMS
1. A vacuum process for etching a metal strip (2) running above at least one counterelectrode (3, 3' , 7) made of conductive material by magnetron sputtering in a vacuum chamber (1) , in which a plasma is created in a gas close to said metal strip {2) so as to generate radicals and/or ions that act on this metal strip (2) , a magnetic confinement circuit (4) being placed above said metal strip (2), characterized in that said counterelectrode (3, 3', 7) has a surface that can move, by rotation and/or by translation, relative to said metal strip {2), said surface being set in motion during the etching and being continuously cleaned by a cleaning device (5, 5', 10) placed in the shadow of said plasma, before again being exposed to said plasma.
2. The etching process as claimed in claim 1, in which said cleaning device (5, 5', 10) is a cleaning device having a localized mechanical action.
3- The etching process as claimed in claim 2, in which said cleaning device (5, 5', 10) consists of a rigid scraper in contact with the moving surface of said counterelectrode (3, 3', 7).
4. The etching process as claimed in any one of claims 1 to 3, in which the matter scraped off the moving surface of said counterelectrode (3, 3', 7) by the action of said cleaning device (5, 5', 10) is recovered by a collecting device (6) placed on the bottom of said vacuum chamber (1).
■5. The etching process as claimed in any one of claims 1 to 4, in which said counterelectrode (3, , 3', 7) is positively biased relative to the metal

strip (2), it being possible for said metal strip (2) to be grounded or not.
6. The etching process as claimed in any one of claims 1 to 4, in which said counterelectrode (3, 3' , 7) is subjected to an AC potential, it being possible for the metal strip (2) to be grounded or not.
7. The process as claimed in any one of claims 1 to 6, in which the vacuum chamber (1) is provided with a counterelectrode (7) consisting of at least two rotating rolls (9, 9') and a tensioned belt (8) on said rolls (9, 9').
8. The process as claimed in any one of claims 1 to If in which said counterelectrode (3, 3' , 7) is cooled.
9. The process as claimed in any one of claims 1 to 8, in which said metal strip (2) is a steel strip.
10. A vacuum installation for etching a metal strip
(2) by magnetron sputtering, comprising a vacuum chamber (1) in which there are at least one counterelectrode (3, 3', 7), means for biasing said metal strip, means for biasing said counterelectrode (3, 3', 7), means for creating a plasma in a gas between said metal strip {2) and
I said counterelectrode {3, 3', 1) , at least one magnetic confinement circuit •( 4) being placed above said metal strip [2) and said counterelectrode (3, 3', 7) having a surface that can move, by rotation and/or by translation,
i relative to said metal strip (2), and a cleaning device (5, 5', 10) for cleaning said moving surface, which is placed in the shadow of said plasma.

11. The etching installation as claimed in claim 10, in which said cleaning device (5, 5' , 10) is a cleaning device having a localized mechanical action.
12. The etching installation as claimed in claim 11, in which said cleaning device (5, 5' , 10) consists of a rigid scraper in contact with the moving surface of said counterelectrode (3, 3', 7).
13. The etching installation as claimed in any one of claims 10 to 12, in which the vacuum chamber (1) further includes a collecting device (6) for collecting the matter scraped off the moving surface of said counterelectrode (3, 3', 7) via the action of said cleaning device (5, 5', 10), said collecting device (6) being placed on the bottom of said vacuum chamber (1) .
14. The etching installation as claimed in any one of claims 10 to 13, in which said counterelectrode (3, 3', 7) is positively biased relative to the
metal strip (2), it being possible for said metal strip (2) to be grounded or not.
15. The etching installation as claimed in any one of claims 10 to 13, in which said counterelectrode (3, 3', 7) is subjected to an AC potential, it being possible for the metal strip (2) to be grounded or not.
16. The installation as claimed in any one of claims 10 to 15, in which the vacuum chamber (1) is
■provided with a counterelectrode (7) consisting of at least two rotating rolls (9, 9') and a tensioned belt (8) on said rolls {9, 9').

17. The installation as claimed in any one of claims 10 to 16, in which said counterelectrode (3, 3', 7} is provided with cooling means.

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Patent Number

258760

Indian Patent Application Number

2813/CHENP/2008

PG Journal Number

06/2014

Publication Date

07-Feb-2014

Grant Date

05-Feb-2014

Date of Filing

05-Jun-2008

Name of Patentee

ARCELORMITTAL FRANCE

Applicant Address

1-5 RUE LUIGI CHERUBINI, 93200 SAINT DENIS

Inventors:

#	Inventor's Name	Inventor's Address
1	MABOGE, CLAUDE	RUE TAYART, 14, B-5650 CASTILLON
2	CORNIL, HUGUES	4 RUE TRIFFOYE, B-4570 MARCHIN
3	DEWEER, BENOIT	AVENUE BRUEGHEL, 6/14, B-1970 WEZEMBEEK-OPPEM

PCT International Classification Number

H01J37/34

PCT International Application Number

PCT/FR06/02415

PCT International Filing date

2006-10-26

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	05292355.4	2005-11-07	EUROPEAN UNION