Title of Invention	VACUUM ARE SOURCE WITH MAGNET FIELD GENERATING EQUIPMENT
Abstract	Vacuum arc source (2) comprising a target (6) with a surface for operating an arc discharge, wherein the target is arranged in the effective area of a device producing a magnetic field, characterized in that the device producing the magnetic field comprises at least two magnet systems (9,10) with opposite poles and is designed so that the component B1 of the magnetic field standing perpendicular to the surface has substantially constant low values of less than 30 Gauss or zero over a large part of the surface.

Title of Invention

VACUUM ARE SOURCE WITH MAGNET FIELD GENERATING EQUIPMENT

Abstract

Vacuum arc source (2) comprising a target (6) with a surface for operating an arc discharge, wherein the target is arranged in the effective area of a device producing a magnetic field, characterized in that the device producing the magnetic field comprises at least two magnet systems (9,10) with opposite poles and is designed so that the component B1 of the magnetic field standing perpendicular to the surface has substantially constant low values of less than 30 Gauss or zero over a large part of the surface.

Full Text	The present invention refers to a vacuum arc source for the operation of an electric arc discharge, an installation equipped with a such arc source, as well as a method for operation of an electric arc discharge as disclosed hereunder. Arc sources as they are known in a vacuum chamber for the evaporation of different materials and/or as ion source, are used for the coating and pre-treatment of different work pieces. On ground of the high point formingly brought energy of the electric arc running on the target surface of the arc source, named in the following sparks, there comes in addition to the emission of gaseous in large part ionized particles, in particular in a "constant burning" of the sparks with the result of an explosion type evaporation, also to the emission of macroparticle whose diameter can reach up to a few micrometers and more. After the coating, consequently the surface roughness as for example of previously polished work pieces is determined mainly through the number and size of macro particles sticking on the layer surface or rather grown in the layer. That is why the so separated layers arc relatively rough, which acts upon disadvantageously in the application of a coated tool or component. Further a large part of macro particle leaves the surface of the target in a relatively flat angle through which in coating processes valuable material gets lost which separates on the inside face of the vacuum chamber. In order to separate smoother layers different solutions were proposed. Thus as for example arc sources were brought out side of the optical view line of the work piece and the ionised particles were driven by means of magnet fields in the direction of the work piece, through which at a high technical expense, in fact smoother layers were achieved but at the same time the coating rate was substantially reduced. Further, different arc sources were developed in order to move the sparks as quickly as possible on a defined path over the target surface and so to avoid a too high energy entry on a small area or even a "constant burning". Therein the spark was forced on a closed circular path as for example through one or more number of magnets moved behind the target. An other possibility to control the sparks is described in US 5.298,136. This document is viewed as next state of the art. An arc. source revealed therein shows a circular shaped target which is covered side wise from behind by a cup shaped pole shoe with a central pole piece led in till to the target backside and a coil assembled in between. Through it over the target a magnet field is generated, whose vertical components shows in centre of target a positive maximum, falls down symmetrically to smaller values till to a negative minimum in border areas in order to rise again followingly asymptotically in direction of the abscissa. Similar magnet fields can also be generated in known way through assembly of permanent magnets at the back side of the target. Therein the passage of field lines through the abscissa (that means zero passage which corresponds to a change of the field direction) on the target surface defines a line (circular shaped) closed in itself, on which the vertical component of the magnet field is zero. On this zero line, as for example in a cathodic actuated target, the spark entering in the target from the plasma corresponding to the technical direction of the current, does not experience any radial, but a high tangential acceleration, since on the same line the parallel component of the magnet field shows a maximum. The high circumferential speed of the spark attained of such type prevents a "seizure" effective, but causes at the same time a poor target utilisation since mainly only a narrow circular ring of the target is removed. In order to improve this additionally a solenoid coil covering the target and the pole shoe in the upper area is planned with which the radius of the zero line generated through pole shoe and coil assembled therein, can be shifted radially. The technical expenditure required for this is however proportionately high since for both the coils in each case an independent current/voltage control unit is to be planned, in doing so at least one from them must be suitable for the transmission of periodically changeable current / voltage signals in order to make possible a periodic expansion/contraction of the zero line on the target. Indeed inspite of the high expenditure also at arc source designed of such type a relatively large area in the middle of target will be removed only less or not at all. The assignment of the present invention lies therein to over come the mentioned disadvantages of the state of the art. In particular the assignment exists therein, to realize a vacuum arc source and a process for operation of an electric arc discharge, which respectively in comparison to commercially used sources or rather in comparison to commercial process, allows altogether improved, more cost effective treatment process with high layer quality. Individually it refers in particular to following points : — improvement of the target utilization. — extension of the target service time — raising of the achievable coating process per target — reduction of the process time — reduction of the surface roughness of the separated layers. For solution of the assignment as per invention a vacuum arc source as per claim 1, a vacuum plant as per claim 17 as well as a procedure as per the process in claim 21 is proposed. Surprisingly, it has shown that at adjustment of a magnet field at the surface of a target whose vertical component B1 takes course over a large part of the surface mainly constantly in proximity to or at. zero, a spark run is made possible in which the spark runs quickly and uniformly over the entire or at least a large part of the target surface. Through it, at one side the area, melted by the individual sparks per time unit at the target surface remains small and the size and number of macroparticles emitted from the melt bath reduces. On the otherside, a better exploitation can be achieved, than with an obligatorily guided spark over a proportionately small area of the target. Advantageously therein the magnet field component B1 is selected less than 30 preferably less than 20, in particular less than 10' Gauss. In the border area of the target surface the values B1R of the vertical magnet field component can be adjusted compared with the values B1 in the middle area of the target surface rising, falling and/or changing the sign. The major part of the surface, that means, the area in which the vertical component B1 runs mainly constantly in proximity to or at zero, stretches therein advantageously from a central area of the target surface up to a border area and covers at least 50%, but preferably 60% of the geometrically determining mass. In case of, as for example, a rectangular target, therefore at least 50 or rather 60% of the sides a, b in case of a circular shaped target therefore at least 50 or rather 60% of the radius. In the border area of the target surface the values B1R of the vertical magnet field components can be adjusted against the value B1 in the central area of the target surface rising, falling and/or changing the sign. The value of the parallel magnet field components B11 can be adjusted therein in the middle mainly likewise on zero, in direction of the border of the target surface but rising, preferably symmetrically rising against the target middle. If as for example in circular shaped targets from the border till in the proximity of central area a magnet field with an approximately linear rising components B11 is applied, then the force acting on the sparks tangentially in clockwise or anticlockwise sense rises against the border of the target through which the spark can run over the radius with approximately constant angular speed. One such magnet field can be manufactured with a vacuum arc source with a magnet field generation device which covers at least two oppositely poled magnet systems. The following, executions describe as examples different vacuum arc sources, with which such a magnet field can be manufactured over the target surface. As first of at least two oppositely poled magnet systems, as for example a first electromagnetic coil brought behind the target can be planned which in itself may be designed again out of multiple number of coils. Advantageously therein the internal dimensions of the first coil cover mainly with a deviation of highest plus/minus 30% preferably plus/minus 20% with the projection of the external dimensions of the surface of the target. Though it, in application of a voltage from the coil through which current flows, a homogeneous, magnet field running mainly vertical to the surface of the target is generated. The parallel components of the magnet field, on the major part of the surface, small in proportion to the vertical components is zero in the central area of the surface and rises against the border. The use of yet a larger first coil is infact possible but less practical, in use of smaller diameter the parallel part will be too large or it comes here even to an undesired change of field direction. Such fields can be generated with solenoid therefore source free coils, without additional pole shoe or rather magnetic core. Depending on distance to target surface or rather diameter of the coil therein the share of the parallel components of the magnet field increases or reduces. Another possibility for the execution of the first magnet system can comprise one or more permanent magnets brought behind the target or rather behind a cooling plate fastened at the back side of the target. The magnet fields generated with it at the target surface in approximately one field should correspond to a solenoid coil, explained as above, thus should be relatively small. Therefore the permanent magnets should either show a less field strength or should be assembled correspondingly distanced from the target. Further it is to be taken care here likewise as in use of a coil described as above, a turn back of the field direction at target surface is not readily caused through the first magnet system. An assembly as known from the state of the art with as for example alternating poling between middle - and border area is therefore to be avoided. A simple possibility presents here as for example the use of thin so called plastoferrite-magnets, which depending on the field strength to be adjusted in shape of single-or multi layered discs or multi corner can be brought as uniformly as possible on the back side of the target analogous to above till in an area of plus/minus 30% preferably plus/minus 20% of the external dimensions of the surface of the target. As second magnet system, advantageously at least one coil assembled covering the first magnet system or rather co-axially to it is planned. This can be assembled as for example covering the first magnet system or rather the target sidewise or preferably behind the first magnet system or rather target. Also for a second coil assembled behind the first magnet system, it is advantageous to plan a larger diameter than that of the first magnet system or rather of the first coil. Likewise a larger number of turns per unit length has proved as favourable since it is easier with it to adjust the vertical magnet field in combination with the action of the first magnet system at the surface mainly on zero. At same number of turns per unit length, this action must be adjusted through a mainly higher current flow, through which it can come to a thermal over loading of the second coil. Additionally with a such second coil, in this case stronger also a second magnet system directed opposing the action of the first magnet system can generate a magnet field acting towards inside in the vacuum chamber which allows a bundling of the other wise diffused arc plasma to a plasma ray named also plasma jet. Therein the opposite parallel components of the second magnet system lift up depending on the distance from target partly or fully, which causes the bundling, while the stronger vertical field of the second magnet system is lifted up only in the direct surface area of the target from the weaker first magnet system. This is advantageous, since with it, a particle flow directed on the work piece to be treated can be generated, which makes possible as for example higher etching rates or a quicker layer growth and through the shortening of process time attainable with it, an altogether longer service life of the target. The assembly of the first as also of the second magnet system behind the target presents further the advantage that both the magnet systems can be fitted with access from outside and are not exposed to the high temperature and a possible coating in the treatment chamber. A comparable effect can also be reached with a coil assembled at a distance before the target. In case a coil is used as first magnet system likewise, then the second coil can be structured similarly or even equally. In a such more or less symmetric assembly of the coils opposite to the target level, also for generation of a plasmajet, the magnet field of the second must not be obligatorily longer than the first coil, with which both coils in similar geometry can be operated also with a common current/voltage source. The remote adjustment of the magnet field can take place therein in simple way through controllable resistances or adjustable distance of at least one coil. Since in this case the second magnet system is exposed to the particle flow of the arc source, however additionally safety - precautions like a cooling or rather detachable safety lining or other known measures are to be planned in order to guarantee a durable operation. In case for the first as well as for the second magnet system in each case at least one coil is used then, as easy to conclude from above stated explanations the respective applied voltage source or rather voltage sources are to be applied such that the coil currents in each case flow in opposite directions that means mainly in clockwise or rather anticlockwise sense. Magnet field generation devices as described above are suitable for the input with cathodically as well as with anodically operated, in particular plane arc sources and can be adjusted in use of at least one coil simply, as for example through change of the coil current but also through change of the distance of at least one magnet system from the target surface, on different target materials and/or target thickness. The target geometry can be matched to the respective requirement and corresponding magnet field generation devices as for example can be executed for round as well as for quadrangular or multiangular sources as per the invention. A change of the coil current(s) during an etching or rather coating process is thus not necessary, when also in principle it is possible. The sparks run further in a random pattern similarly as known from so called random arc - sources, over the target surface, but are guided or rather acclerated so through the magnet fields of the arc sources executed as per the invention that the sparks are finely dispersed and the splashing frequencies are mainly reduced. Surprisingly therein also in the middle area of the target, where vertical as well as also parallel magnet field components are very small or rather zero no seizure of the spark could be established. Through the standard effect achievable, with an arc source as per invention the generated plasma jet can be steered advantageously through a magnet field generated additionally in the chamber of the vacuum treatment plant. In case as for example one or multiple number of arc sources are assembled in direction of the axle of a vacuum treatment plant and at the same time at least a further electro magnetic coil assembled concentric to the installation axle is planned then with it the plasma jet generated from the arc source can be deflected. In case at least one further coil is connected to a periodically changeable current source with control unit, then the plasma jet can be directed variably on different areas in the chamber. As for example the plasmajet for etching process can be guided past the work piece or for coating process preferably periodically over the work piece. There in it has proved at least in symmetric assembly of multiple number of sources around an installation axle as advantageous to select such a coil assembly, with which to the extent possible a uniform axle parallel field can be generated in the chamber. This is attained as for example through an installation with at least two further electro magnetic coils in which the further coils are assembled preferably in the upper as well as lower or rather at the correspondingly side wise bordering areas of the installation concentric to the installation axle. The coils can therein show a different or a same diameter corresponding mainly to a Helmholtz coil assembly. The invention is further described now with the help of/schematic Figures in the , way of examples. Figure 1 Arc source with two magnet systems. Figure 2 Spark course on target surface. Figure 3 Course of magnet field components as per the state of the art. Figure 4 Magnetic field vectors to Figure 3. Figure 5 Course of the magnet field components of an arc source as per invention. Figure 6 Magnetic field vectors to Figure 5. Figure 7 Arc source with a covering coil. Figure 8 Arc source with coil before target. Figure 9 Section through a coating installation Figure 10 Cross section of a coating installation with 6 sources. Figure 11 B1 - Course for optimal operation Figure 12 B11 - Course for optimal operation Figure 13 B1 - Course at spark in the centre. Figure 14 B11 - Course at spark in the centre. Figure 15 B1 - Course at spark at border. Figure 16 B11 - Course at spark at border. Figure 1 Shows an arc source 2 as per invention installed in the chamber of a vacuum treatment plant provided with gas supply 4 and diverse current supply-and pump units not shown here closer, which works upon a work piece 3. In the represented execution both the magnet systems 9, 10 are designed in shape of electro magnetic coils and are assembled behind the target 6 in or rather at a source slide in module 7 shutting off in combination with the target back plate 8, the installation against atmoshphere. The first coil assigned to the first magnet system 9 is located directly behind the target 6 or rather behind a target back plate 8 water cooled in known way. The second coil assigned to the second magnet system 10 is like wise brought behind the target 6, has however a larger internal -as well as external diameter than the first coil 9. The distance between first coil 9 and second coil 10 were adjusted therein between 0 and 200 mm, in a few execution examples on 67 mm. Both coils are located out side of the chamber, are easily accessible with it and if required, can be cooled in simple way. For supply of the coils in this case two independent direct current voltage supplies 11, 12 are planned which supply the required direct current for the respective process or rather for the respective target. As targets, as for example round blanks with a diameter of 160 mm and a thickness of 6 mm out of different materials like as for example Ti or rather TiAl can be produced. Larger as well as smaller target thickness as also other shapes as known to specialists are possible. The coil geometry as well as an exemplary adjustment of coil current are visible from Table1 . Inorder to attain the desired effect both the coils are so inter connected therein with the power instruments that the current flowing through the both coils are electrically of opposite directions. Preferred operating parameters and limiting values for the operation of a corresponding arc source are summarised in Table 2 (Target diameter about 160 mm, d=6 - 12 mm, target material : Ti or rather TiAl). In Table 3, additionally two, as examples operation works for the separation of TIN or rather TiAIN are stated in doing so at the substrata a so called bias voltage was applied. Table 3 Bias [v] Ar [seem] N2 [seem] P [mbar] TIN 100 400 800 3.8 . 102 TIAIN 40-150 400 800 3.8 . 102 The experiments were carried out on a RCS - coating installation of the firm Balzers with octagonal cross section and about 1000 I coating volumes. The diameter of coating chamber amounted to 1070 mm, the height 830 mm. Figure 2 shows schematically at the example of a circular shaped target 6 the forces acting on a spark, of a radially symmetric magnet field generated at the target surface. The spark is considered therein as moved point charge Qarc. In general a charged particle, moved in the magnet field through the force F=Q(vxB) is deflected. Therein, F is the force working on a charge Q moved in the magnet field, V is the speed of charge Q moved right angularly to the field lines and B is the magnetic induction of the field. If one considers the current flow larc of a spark, directed mainly vertical on the target surface, under neglect of the minor influence facing the applied magnet field through the electro magnetic field of the target cathode, then the charged particle experiences through a force Fn directed parallel to the surface and with it vertical to the current flow larc, of a radially symmetric magnet field Bn an acceleration of the course of the spark in right angle to the field line that means depending on field direction in clockwise or anticlockwise sense. On the other hand a magnet field component B1- or rather B1+ of the external magnet field, directed vertical to target surface, in the first place, does not cause any defleption of the vertically entering charge carrier of the current flow larc, since the cross product of the vectors vxB is zero here. First after the spark, through deflection at arrival on the target surface experiences a deflection opposite to the clockwise sense shown as for example in the plan view and shows with it also a speed component parallel to the target surface then both forces F±- and F±+ act generated through the vertical magnet field components B±- and B±+. Through B±- the spark as represented is deflected towards the target centre, B±+ on the other hand gives the spark a speed component which moves it towards target border. This effect, as mentioned in the acknowledgement of the state of the art, can be used through a dual pole assembly, with a periodically changeable current supply in order to guide the sparks along a radially displaceable zero line of the vertical magnet field components B± over the target surface. Figure 3 shows as example for a known magnet field structured through permanent magnets their parallel as well as vertical components on the target surface. In this magnet assembly, magnets with identical alignment of the poles, circulating on the back side of the target in the border area are brought, which one or multiple number of oppositely poled magnets face in the centre of the target. In comparison with magnetron assemblies for sputter magnetrons, the magnets assembled similarly here show mainly a less field strength, in order to reach the desired guiding effect. Figure 4 shows the vectorial representation resulting from Figure 3 of the force acting on a, spark larc burning vertically from the plasma on the surface or rather circularly deflected through the parallel magnet field at the positions 1-7 of the target surface. Therein B11 causes the tangentially working force F11 B1 causes a force F± in the target level, normal to it thus working radially. In the practical application it shows that the spark course runs mainly on a circular ring at a radial distance of 4-6 cm from the target centre and from there periodically contracts in the target centre. This course of the spark results, since at a radial distance of 5 cm the vertical magnetic field is zero, and the parallel field is maximum. Through the parallel field the spark experiences a movement in tangential direction as shown in Figure 2. Since the vertical field at a radial distance between 4-6 cm is irrelevantly different from zero, the spark is neither moved to the target centre nor to the target border and runs mainly in the area of the mentioned circular ring. In the target centre, as represented in Figure 3 the parallel component of the magnet field intersects however the zero line while the vertical component runs through a maximum. A spark escaped once, from the guiding of the strong circular ring shaped parallel magnet field in direction of the target centre, experiences there no or at least only yet a minor deflection, since the vertically occuring spark is hardly accelerated through the weak force F11, due to which the large force F1, is hardly effective. Therefore the spark slows down in the central area it's movement over the target surface and heats this locally so strongly that the target material evaporates in explosive way, upon which the spark extinguishes. This leads also to an increased emission of neutral particles (splash) and increased target removal in the central area of the target. This course of the spark proves in the practical field also therefore as unfavourable since only a proportionately smaller part of the target surface is removed, which leads to development of erosion profile and that means frequent change in order to maintain the mechanical stability of the target. Thus only a fraction of the frequently expensive target material can be evaporated before end of target service life. In Figure 5 the course of the vertical B1 and parallel B11 components of a magnet field as per invention is represented as it as for example, through an arc source described in Figure 1 is generated at the target surface or rather directly in front of it, through super position of two coil fields. Therein the coil currents corresponding to Table 1 were adjusted constant to 1.5 A for the first coil 9 or rather 5A for the second coil 10, instead of (1) and (2) better take the indicaters from Figure 1. The magnet field generated through it distinguishes itself through a course of the vertical component, which other than in Figure 3 is constant over a wide area and shows clearly smaller values. So the vertical component B1 runs here between +5 and -5 Gauss whereas the vertical component in Figure 3 runs between +80 and -120 Gauss, with a represented minimum in central area. Also the parallel component B11 reprensented in Figure 5 is wholly weaker than that in Figure 3. From a value of about 20 Gauss beginning at the target border B11 runs with a gradient of about 4 Gauss/cm, quasi linear till in the proximity of the turning point (corresponds to a minimum in polar co-ordinates representation). First in this direct surrounding the curve clearly flattens out. The development of one or more number of B1 zero lines in combination with maximum B11- values is therein deliberately avoided through a first coil, whose internal diameter approximately corresponds to the target projection, with which the spark is not forced on a preferred path and the formation of represented removal profile, like as for example circulating race tracks is avoided. Similar magnet fields can also be generated in known way through permanent magnets. Figure 6 shows analogous to Figure 4 a vectorial representation of the force working on a spark through an arc source as per invention, as described under Figure 1 at the positions 1-7 of the target surface. This could also explain how an executed or rather operated magnet system as per invention effectively prevents that the spark contracts in damaging way toward the target centre. Through the parallel force components F11 mainly continuously rising out wards the spark receives a relatively constant anguler speed over the total radial area of the target, the spark therefore runs all the more quickly, further it is distanced from the target centre. At the same time the centripetal force components 1 working in the central area is less than that in Figure 4. In the operation of a such arc source it is observed that it comes to a fine ramification of the arc current in many small sparRs, which flow-off the entire area of the target. Further the magnet field arisen through the superimposition of both the coil fields forms a remote field, which causes a bundling of the plasmas to a plasma - jet, which from it's side can be deflected through additional coils. Since at equal target efficiency the removal is at least likewise large as in conventional arc sources, it comes in alignment of the ion flow in direction of the work piece 3 to a higher coating rate. This bundling can be adjusted corresponding to the requirements in wide extent, as for example through adjustment of coil currents on the respective specially geometric proportion like as for example desired coating height, substrata target distance etc. Figure 7 and Figure 8 show two further executions of an arc source as per invention, in doing so in Figure 7 the second magnet system 10 covers the first magnet system 9 while in Figure 8 the second magnet system 10 is assembled before the target 6. In an arc source as shown in Figure 8 the second magnet system can also show similar dimensions like the first system, in particular when first and second system are assembled operation symmetrically against the target and the internal diameters are selected at least equal or greater than the external dimensions of the target. Figure 9 shows a vacuum treatment plant 1 with arc sources 2, which act sidewise on one or more number of work pieces 3 moved around the installation axle 13. For the vertical deflection of the plasma jet further coils 14 are planned in Helmholtz assembly. Figure 10 shows a coating installation 1 with 6 arc sources 2 in the cross section in which all sources 2 are aligned mainly right angularly in direction of the installation axle 13. Figure 11 to Figure 16 show the courses generated in different adjustment of coil current, of B1- or rather B11- components of the magnet field at the target surface. The arc sources were operated therein corresponding to the operating parameters described in Figure 1, in order to determine the optimum adjustment area and limits. So the Figures 11 and 12 show different, corresponding B1- or rather B1- curves of the magnet field with relevant coil adjustment, in which a desired finely distributed spark course could be attained. Here in it is to be noted, that B1-or rather B11- values in provided geometric configuration can not be adjusted independent of each other, due to which in each case only one equally described B11- distribution in Figure 12 corresponds to a B1- distribution in Figure 11. Figure 13 and 14 show a border case, in which the bend infact runs yet finally distributed, but already with free eye first sign of a periodic contractions in the centre, are to be identified. In case the B1- distribution is shifted yet clearly further to negative values it, comes to a coarser spark course and to a too strong contraction in the central area. Figure 15 and 16 show a further limiting case, Also here the spark pattern is yet sufficiently finelly distributed, however first sign of a periodic pushings of spark in the border area of the target through the magnet field applied herein are to be identified. In case the B1- distribution is shifted yet clearly further to positive values, it comes to a coarser spark course at the border of the target. It was further found out, that B1- distribution, which lie on both sides of the zero line, allow higher differences of magnet field strength, that means a non- uniform B1- distribution at the target surface, in approximately unchanged fine and evenly distributed spark course than, that B1- distribution which lie fully over or rather under the zero line. We claim: 1. Vacuum arc source (2) comprising a target (6) with a surface for operating an arc discharge, wherein the target is arranged in the effective area of a device producing a magnetic field, characterized in that the device producing the magnetic field comprises at least two magnet systems (9,10) with opposite poles and is designed so that the component B± of the magnetic field standing perpendicular to the surface has substantially constant low values of less than 30 Gauss or zero over a large part of the surface. 2. Arc source as claimed in claim 1, wherein the value of the perpendicular magnetic field component B± is less than 20, preferably less than 10 Gauss. 3. Arc source as claimed in any preceding claims, the large part of the surface extends from a middle area of the target surface to an edge zone, such that the large part includes at least 50%, particularly preferably 60% or more of the geometrically decisive mass of the target surface. 4. Arc source as claimed in any of the preceding claims, wherein in the edge zone of the target surface, the values B1R of the perpendicular magnetic field component rise, fall and/or change signs compared with the values B±M in the middle area of the target surface. 5. Arc source as claimed In any of the preceding claims, wherein the value of the parallel magnetic field component B\|\| is substantially zero in the middle and rises or falls in the direction of the edge of the target surface, preferably symmetrically in relation to the target center, particularly preferably rises substantially linearly. 6. Arc source as claimed in any of the preceding claims, wherein the first of the at least two magnet systems with opposite poles comprises at least one first electromagnetic coil placed behind the target. 7. Arc source as claimed in claim 6, wherein the inner dimensions of the first coil substantially coincide, with a deviation of maximum plus/minus 30%, preferably plus/minus 20%, with the projection of the outer dimensions of the surface. 8. Arc source as claimed in any of claims 1 to 5, wherein the first of the at least two magnet systems with opposite poles comprises one or more permanent magnets placed behind the target. 9. Arc source as claimed in claim 8, wherein the permanent magnet or magnets either themselves have low field strength, or have a distance from the target such that the field strength at the target surface is low. 10. Arc source as claimed in any of the preceding claims, wherein the second of the at least two magnet systems with opposite poles comprises at least one second coil arranged coaxially to the first magnet system. 11. Arc source as claimed in claim 10, wherein the second coil (10) is arranged behind the first magnet system (9). 12. Arc source as claimed in claim 10, wherein the second coil (10) is arranged at a distance in front of the target. 13. Arc source as claimed in claim 10, wherein the second coil (10) surrounds the first magnet system (9) at least partly coaxially. 14. Arc source as claimed in claims 10 to 13, wherein the second coil (10) has a higher number of windings and/or a larger diameter than the first coil. 15. Arc source as claimed in any of the preceding claims, wherein the target (6) is connected as a cathode. 16. Arc source as claimed in any of the preceding claims, wherein the target (6) is connected as an anode. 17. Vacuum system in which at least one arc source (2) is arranged as claimed in any of claims 1 to 16. 18. System as claimed in claim 17, wherein the at least one arc source acts in the direction of the system axis and has at least one further electromagnetic coil arranged concentrically to the system axis in order to deflect the plasma beam produced. 19. System as claimed in claim 18, wherein the at least one further coil is connected to at least one temporally varying current source with a control unit in order to deflect variably the alignment of the plasma beam produced by the at least one arc source. 20. System as claimed in one of claims 18 and 19, wherein at least two further electromagnetic coils, preferably in the upper and lower or corresponding laterally adjacent areas of the system, are arranged concentrically to the system axis and have a different or the same diameter or a design substantially corresponding to a Helmholz coil arrangement. 21. Method for operating an arc discharge on the target surface of an arc source (2) using a device producing a magnetic field, characterized in that the device for producing a magnetic field generates a magnetic field on the surface such that its perpendicular component Bl over a large part of the surface has a substantially constantly low value of less than 30 Gauss or zero. 22. Method as claimed in claim 21, wherein the value Bl of the perpendicular magnetic field component is set less than 30, preferably less than 20, particularly less than 10 Gauss. 23. Method as claimed in claims 21 and 22, wherein the magnetic field is set so that the large part of the surface with component Bl running perpendicularly substantially constantly near or at zero extends from the middle area of the target surface to an edge zone, such that the middle area comprises at least 60%, particularly preferably 60% or more of the geometrically decisive mass of the target surface. 24. Method as claimed in any of claims 21 to 23, wherein in the edge zone of the target surface the values B1R of the perpendicular magnetic field component are set to rise, fall and/or change signs compared with the values B1M in the middle area of the target surface 25. Method as claimed in any of claims 21 to 24, wherein the value of the parallel magnetic field component B\|\| is set substantially at zero in the middle and rises in the direction of the edge zone of the target surface, preferably symmetrically in relation to the middle of the target, so that the force acting tangentially on the spark clockwise or counter-clockwise rises toward the edge zone of the target. 26. Method as claimed in claims 21 to 24, wherein a magnetic field aligned substantially perpendicular to the surface is also produced in an area in front of the target. 27. Method as claimed in any of claims 21 to 26, wherein the magnetic field strength is set corresponding to the target material and/or target thickness. 28. Method as claimed in any of claims 21 to 27, wherein the device producing the magnetic field comprises at least one coil placed behind the target, and a voltage source is applied to at least one coil to adjust the magnetic field, so that current flows in a first direction. 29. Method as claimed in any of claims 21 to 27, wherein the device for producing the magnetic field comprises at least one magnet system constructed from of one or more permanent magnets and arranged behind the target. 30. Method as claimed in any of claims 28 and 29, wherein at least one second coil is placed behind, in front of or around the target, and to adjust the magnetic field a voltage is applied to the second coil such that a second magnetic field is produced that is aligned opposite the magnetic field produced by the first magnet system. 31. Method for coating a workpiece, in particular a tool and/or a component, using one of the methods in claims 20 to 29. 32. Method for coating a workpiece, in particular a tool and/or a component, using an arc source as claimed in claims 1 to 16. ABSTRACT TITLE: VACUUM ARC SOURCE WITH MAGNET FIELD GENERATING EQUIPMENT Vacuum arc source (2) comprising a target (6) with a surface for operating an arc discharge, wherein the target is arranged in the effective area of a device producing a magnetic field, characterized in that the device producing the magnetic field comprises at least two magnet systems (9,10) with opposite poles and is designed so that the component B1 of the magnetic field standing perpendicular to the surface has substantially constant low values of less than 30 Gauss or zero over a large part of the surface. FIG. 1 Vacuum arc source (2) comprising a target (6) with a surface for operating an arc discharge, wherein the target is arranged in the effective area of a device producing a magnetic field, characterized in that the device producing the magnetic field comprises at least two magnet systems (9,10) with opposite poles and is designed so that the component B1 of the magnetic field standing perpendicular to the surface has substantially constant low values of less than 30 Gauss or zero over a large part of the surface.

Full Text

The present invention refers to a vacuum arc source for the operation of an electric arc discharge, an installation equipped with a such arc source, as well as a method for operation of an electric arc discharge as disclosed hereunder.
Arc sources as they are known in a vacuum chamber for the evaporation of different materials and/or as ion source, are used for the coating and pre-treatment of different work pieces. On ground of the high point formingly brought energy of the electric arc running on the target surface of the arc source, named in the following sparks, there comes in addition to the emission of gaseous in large part ionized particles, in particular in a "constant burning" of the sparks with the result of an explosion type evaporation, also to the emission of macroparticle whose diameter can reach up to a few micrometers and more. After the coating, consequently the surface roughness as for example of previously polished work pieces is determined mainly through the number and size of macro particles sticking on the layer surface or rather grown in the layer. That is why the so separated layers arc relatively rough, which acts upon disadvantageously in the application of a coated tool or component. Further a large part of macro particle leaves the surface of the target in a relatively flat angle through which in coating processes valuable material gets lost which separates on the inside face of the vacuum chamber. In order to separate

smoother layers different solutions were proposed. Thus as for example arc sources were brought out side of the optical view line of the work piece and the ionised particles were driven by means of magnet fields in the direction of the work piece, through which at a high technical expense, in fact smoother layers were achieved but at the same time the coating rate was substantially reduced.
Further, different arc sources were developed in order to move the sparks as quickly as possible on a defined path over the target surface and so to avoid a too high energy entry on a small area or even a "constant burning". Therein the spark was forced on a closed circular path as for example through one or more number of magnets moved behind the target.
An other possibility to control the sparks is described in US 5.298,136. This document is viewed as next state of the art. An arc. source revealed therein shows a circular shaped target which is covered side wise from behind by a cup shaped pole shoe with a central pole piece led in till to the target backside and a coil assembled in between. Through it over the target a magnet field is generated, whose vertical components shows in centre of target a positive maximum, falls down symmetrically to smaller values till to a negative minimum in border areas in order to rise again followingly asymptotically in direction of the abscissa. Similar magnet fields can also be generated in known way through assembly of permanent magnets at the back side of the target. Therein the passage of field lines through the abscissa (that means zero passage which

corresponds to a change of the field direction) on the target surface defines a line (circular shaped) closed in itself, on which the vertical component of the magnet field is zero. On this zero line, as for example in a cathodic actuated target, the spark entering in the target from the plasma corresponding to the technical direction of the current, does not experience any radial, but a high tangential acceleration, since on the same line the parallel component of the magnet field shows a maximum. The high circumferential speed of the spark attained of such type prevents a "seizure" effective, but causes at the same time a poor target utilisation since mainly only a narrow circular ring of the target is removed.
In order to improve this additionally a solenoid coil covering the target and the pole shoe in the upper area is planned with which the radius of the zero line generated through pole shoe and coil assembled therein, can be shifted radially.
The technical expenditure required for this is however proportionately high since for both the coils in each case an independent current/voltage control unit is to be planned, in doing so at least one from them must be suitable for the transmission of periodically changeable current / voltage signals in order to make possible a periodic expansion/contraction of the zero line on the target. Indeed inspite of the high expenditure also at arc source designed of such type a relatively large area in the middle of target will be removed only less or not at all.

The assignment of the present invention lies therein to over come the mentioned disadvantages of the state of the art. In particular the assignment exists therein, to realize a vacuum arc source and a process for operation of an electric arc discharge, which respectively in comparison to commercially used sources or rather in comparison to commercial process, allows altogether improved, more cost effective treatment process with high layer quality. Individually it refers in particular to following points :
— improvement of the target utilization.
— extension of the target service time
— raising of the achievable coating process per target
— reduction of the process time
— reduction of the surface roughness of the separated layers.
For solution of the assignment as per invention a vacuum arc source as per claim 1, a vacuum plant as per claim 17 as well as a procedure as per the process in claim 21 is proposed.
Surprisingly, it has shown that at adjustment of a magnet field at the surface of a target whose vertical component B1 takes course over a large part of the surface mainly constantly in proximity to or at. zero, a spark run is made possible in which the spark runs quickly and uniformly over the entire or at least

a large part of the target surface. Through it, at one side the area, melted by the individual sparks per time unit at the target surface remains small and the size and number of macroparticles emitted from the melt bath reduces. On the otherside, a better exploitation can be achieved, than with an obligatorily guided spark over a proportionately small area of the target.
Advantageously therein the magnet field component B1 is selected less than 30 preferably less than 20, in particular less than 10' Gauss. In the border area of the target surface the values B1R of the vertical magnet field component can be adjusted compared with the values B1 in the middle area of the target surface rising, falling and/or changing the sign.
The major part of the surface, that means, the area in which the vertical component B1 runs mainly constantly in proximity to or at zero, stretches therein advantageously from a central area of the target surface up to a border area and covers at least 50%, but preferably 60% of the geometrically determining mass.
In case of, as for example, a rectangular target, therefore at least 50 or rather 60% of the sides a, b in case of a circular shaped target therefore at least 50 or rather 60% of the radius.
In the border area of the target surface the values B1R of the vertical magnet field components can be adjusted against the value B1 in the central area of the target surface rising, falling and/or changing the sign.

The value of the parallel magnet field components B11 can be adjusted therein in the middle mainly likewise on zero, in direction of the border of the target surface but rising, preferably symmetrically rising against the target middle. If as for example in circular shaped targets from the border till in the proximity of central area a magnet field with an approximately linear rising components B11 is applied, then the force acting on the sparks tangentially in clockwise or anticlockwise sense rises against the border of the target through which the spark can run over the radius with approximately constant angular speed.
One such magnet field can be manufactured with a vacuum arc source with a magnet field generation device which covers at least two oppositely poled magnet systems.
The following, executions describe as examples different vacuum arc sources, with which such a magnet field can be manufactured over the target surface.
As first of at least two oppositely poled magnet systems, as for example a first electromagnetic coil brought behind the target can be planned which in itself may be designed again out of multiple number of coils. Advantageously therein the internal dimensions of the first coil cover mainly with a deviation of highest plus/minus 30% preferably plus/minus 20% with the projection of the external dimensions of the surface of the target. Though it, in application of a voltage from the coil through which current flows, a homogeneous, magnet field running mainly vertical to the surface of the target is generated. The parallel components

of the magnet field, on the major part of the surface, small in proportion to the vertical components is zero in the central area of the surface and rises against the border. The use of yet a larger first coil is infact possible but less practical, in use of smaller diameter the parallel part will be too large or it comes here even to an undesired change of field direction.
Such fields can be generated with solenoid therefore source free coils, without additional pole shoe or rather magnetic core. Depending on distance to target surface or rather diameter of the coil therein the share of the parallel components of the magnet field increases or reduces.
Another possibility for the execution of the first magnet system can comprise one or more permanent magnets brought behind the target or rather behind a cooling plate fastened at the back side of the target. The magnet fields generated with it at the target surface in approximately one field should correspond to a solenoid coil, explained as above, thus should be relatively small. Therefore the permanent magnets should either show a less field strength or should be assembled correspondingly distanced from the target. Further it is to be taken care here likewise as in use of a coil described as above, a turn back of the field direction at target surface is not readily caused through the first magnet system. An assembly as known from the state of the art with as for example alternating poling between middle - and border area is therefore to be avoided. A simple possibility presents here as for example the use of thin so called plastoferrite-magnets, which depending on the field strength to be adjusted in shape of single-or multi layered discs or multi corner can be brought as

uniformly as possible on the back side of the target analogous to above till in an area of plus/minus 30% preferably plus/minus 20% of the external dimensions of the surface of the target.
As second magnet system, advantageously at least one coil assembled covering the first magnet system or rather co-axially to it is planned. This can be assembled as for example covering the first magnet system or rather the target sidewise or preferably behind the first magnet system or rather target.
Also for a second coil assembled behind the first magnet system, it is advantageous to plan a larger diameter than that of the first magnet system or rather of the first coil. Likewise a larger number of turns per unit length has proved as favourable since it is easier with it to adjust the vertical magnet field in combination with the action of the first magnet system at the surface mainly on zero. At same number of turns per unit length, this action must be adjusted through a mainly higher current flow, through which it can come to a thermal over loading of the second coil. Additionally with a such second coil, in this case stronger also a second magnet system directed opposing the action of the first magnet system can generate a magnet field acting towards inside in the vacuum chamber which allows a bundling of the other wise diffused arc plasma to a plasma ray named also plasma jet. Therein the opposite parallel components of the second magnet system lift up depending on the distance from target partly or fully, which causes the bundling, while the stronger vertical field of the second magnet system is lifted up only in the direct surface area of the target from the

weaker first magnet system. This is advantageous, since with it, a particle flow directed on the work piece to be treated can be generated, which makes possible as for example higher etching rates or a quicker layer growth and through the shortening of process time attainable with it, an altogether longer service life of the target.
The assembly of the first as also of the second magnet system behind the target presents further the advantage that both the magnet systems can be fitted with access from outside and are not exposed to the high temperature and a possible coating in the treatment chamber.
A comparable effect can also be reached with a coil assembled at a distance before the target. In case a coil is used as first magnet system likewise, then the second coil can be structured similarly or even equally. In a such more or less symmetric assembly of the coils opposite to the target level, also for generation of a plasmajet, the magnet field of the second must not be obligatorily longer than the first coil, with which both coils in similar geometry can be operated also with a common current/voltage source. The remote adjustment of the magnet field can take place therein in simple way through controllable resistances or adjustable distance of at least one coil. Since in this case the second magnet system is exposed to the particle flow of the arc source, however additionally safety - precautions like a cooling or rather detachable safety lining or other known measures are to be planned in order to guarantee a durable operation.

In case for the first as well as for the second magnet system in each case at least one coil is used then, as easy to conclude from above stated explanations the respective applied voltage source or rather voltage sources are to be applied such that the coil currents in each case flow in opposite directions that means mainly in clockwise or rather anticlockwise sense. Magnet field generation devices as described above are suitable for the input with cathodically as well as with anodically operated, in particular plane arc sources and can be adjusted in use of at least one coil simply, as for example through change of the coil current but also through change of the distance of at least one magnet system from the target surface, on different target materials and/or target thickness. The target geometry can be matched to the respective requirement and corresponding magnet field generation devices as for example can be executed for round as well as for quadrangular or multiangular sources as per the invention.
A change of the coil current(s) during an etching or rather coating process is thus not necessary, when also in principle it is possible. The sparks run further in a random pattern similarly as known from so called random arc - sources, over the target surface, but are guided or rather acclerated so through the magnet fields of the arc sources executed as per the invention that the sparks are finely dispersed and the splashing frequencies are mainly reduced. Surprisingly therein also in the middle area of the target, where vertical as well as also parallel magnet field components are very small or rather zero no seizure of the spark could be established.

Through the standard effect achievable, with an arc source as per invention the generated plasma jet can be steered advantageously through a magnet field generated additionally in the chamber of the vacuum treatment plant. In case as for example one or multiple number of arc sources are assembled in direction of the axle of a vacuum treatment plant and at the same time at least a further electro magnetic coil assembled concentric to the installation axle is planned then with it the plasma jet generated from the arc source can be deflected. In case at least one further coil is connected to a periodically changeable current source with control unit, then the plasma jet can be directed variably on different areas in the chamber. As for example the plasmajet for etching process can be guided past the work piece or for coating process preferably periodically over the work piece.
There in it has proved at least in symmetric assembly of multiple number of sources around an installation axle as advantageous to select such a coil assembly, with which to the extent possible a uniform axle parallel field can be generated in the chamber. This is attained as for example through an installation with at least two further electro magnetic coils in which the further coils are assembled preferably in the upper as well as lower or rather at the correspondingly side wise bordering areas of the installation concentric to the installation axle. The coils can therein show a different or a same diameter corresponding mainly to a Helmholtz coil assembly.
The invention is further described now with the help of/schematic Figures in the ,

way of examples.
Figure 1 Arc source with two magnet systems.
Figure 2 Spark course on target surface.
Figure 3 Course of magnet field components as per the state of the art.
Figure 4 Magnetic field vectors to Figure 3.
Figure 5 Course of the magnet field components of an arc source as per invention.
Figure 6 Magnetic field vectors to Figure 5.
Figure 7 Arc source with a covering coil.
Figure 8 Arc source with coil before target.
Figure 9 Section through a coating installation
Figure 10 Cross section of a coating installation with 6 sources.
Figure 11 B1 - Course for optimal operation
Figure 12 B11 - Course for optimal operation
Figure 13 B1 - Course at spark in the centre.
Figure 14 B11 - Course at spark in the centre.
Figure 15 B1 - Course at spark at border.
Figure 16 B11 - Course at spark at border.
Figure 1 Shows an arc source 2 as per invention installed in the chamber of

a vacuum treatment plant provided with gas supply 4 and diverse current supply-and pump units not shown here closer, which works upon a work piece 3. In the represented execution both the magnet systems 9, 10 are designed in shape of electro magnetic coils and are assembled behind the target 6 in or rather at a source slide in module 7 shutting off in combination with the target back plate 8, the installation against atmoshphere. The first coil assigned to the first magnet system 9 is located directly behind the target 6 or rather behind a target back plate 8 water cooled in known way. The second coil assigned to the second magnet system 10 is like wise brought behind the target 6, has however a larger internal -as well as external diameter than the first coil 9.
The distance between first coil 9 and second coil 10 were adjusted therein between 0 and 200 mm, in a few execution examples on 67 mm. Both coils are located out side of the chamber, are easily accessible with it and if required, can be cooled in simple way. For supply of the coils in this case two independent direct current voltage supplies 11, 12 are planned which supply the required direct current for the respective process or rather for the respective target.
As targets, as for example round blanks with a diameter of 160 mm and a thickness of 6 mm out of different materials like as for example Ti or rather TiAl can be produced. Larger as well as smaller target thickness as also other shapes as known to specialists are possible. The coil geometry as well as an exemplary adjustment of coil current are visible from Table1 . Inorder to attain the desired effect both the coils are so inter connected therein with the power instruments that the current flowing through the both coils are electrically of opposite directions.

Preferred operating parameters and limiting values for the operation of a corresponding arc source are summarised in Table 2 (Target diameter about 160 mm, d=6 - 12 mm, target material : Ti or rather TiAl).

In Table 3, additionally two, as examples operation works for the separation of TIN or rather TiAIN are stated in doing so at the substrata a so called bias voltage was applied.

Table 3
Bias [v] Ar [seem] N2 [seem] P [mbar]
TIN 100 400 800 3.8 . 102
TIAIN 40-150 400 800 3.8 . 102
The experiments were carried out on a RCS - coating installation of the firm Balzers with octagonal cross section and about 1000 I coating volumes. The diameter of coating chamber amounted to 1070 mm, the height 830 mm.
Figure 2 shows schematically at the example of a circular shaped target 6 the forces acting on a spark, of a radially symmetric magnet field generated at the target surface. The spark is considered therein as moved point charge Qarc.
In general a charged particle, moved in the magnet field through the force F=Q(vxB) is deflected. Therein, F is the force working on a charge Q moved in the magnet field, V is the speed of charge Q moved right angularly to the field lines and B is the magnetic induction of the field. If one considers the current flow larc of a spark, directed mainly vertical on the target surface, under neglect of the minor influence facing the applied magnet field through the electro magnetic field of the target cathode, then the charged particle experiences through a force Fn directed parallel to the surface and with it vertical to the current flow larc, of a radially symmetric magnet field Bn an acceleration of the course of the spark in right angle to the field line that means depending on field direction in clockwise or anticlockwise sense. On the other hand a magnet field component B1- or rather B1+ of the external magnet field, directed vertical to target surface, in the first place, does not cause any defleption of the vertically

entering charge carrier of the current flow larc, since the cross product of the vectors vxB is zero here. First after the spark, through deflection at arrival on the target surface experiences a deflection opposite to the clockwise sense shown as for example in the plan view and shows with it also a speed component parallel to the target surface then both forces F±- and F±+ act generated through the vertical magnet field components B±- and B±+. Through B±- the spark as represented is deflected towards the target centre, B±+ on the other hand gives the spark a speed component which moves it towards target border.
This effect, as mentioned in the acknowledgement of the state of the art, can be used through a dual pole assembly, with a periodically changeable current supply in order to guide the sparks along a radially displaceable zero line of the vertical magnet field components B± over the target surface.
Figure 3 shows as example for a known magnet field structured through permanent magnets their parallel as well as vertical components on the target surface. In this magnet assembly, magnets with identical alignment of the poles, circulating on the back side of the target in the border area are brought, which one or multiple number of oppositely poled magnets face in the centre of the target. In comparison with magnetron assemblies for sputter magnetrons, the magnets assembled similarly here show mainly a less field strength, in order to reach the desired guiding effect.
Figure 4 shows the vectorial representation resulting from Figure 3 of the force acting on a, spark larc burning vertically from the plasma on the surface or rather circularly deflected through the parallel magnet field at the positions 1-7 of the

target surface. Therein B11 causes the tangentially working force F11 B1 causes a force F± in the target level, normal to it thus working radially. In the practical application it shows that the spark course runs mainly on a circular ring at a radial distance of 4-6 cm from the target centre and from there periodically contracts in the target centre. This course of the spark results, since at a radial distance of 5 cm the vertical magnetic field is zero, and the parallel field is maximum. Through the parallel field the spark experiences a movement in tangential direction as shown in Figure 2. Since the vertical field at a radial distance between 4-6 cm is irrelevantly different from zero, the spark is neither moved to the target centre nor to the target border and runs mainly in the area of the mentioned circular ring.
In the target centre, as represented in Figure 3 the parallel component of the magnet field intersects however the zero line while the vertical component runs through a maximum. A spark escaped once, from the guiding of the strong circular ring shaped parallel magnet field in direction of the target centre, experiences there no or at least only yet a minor deflection, since the vertically occuring spark is hardly accelerated through the weak force F11, due to which the large force F1, is hardly effective. Therefore the spark slows down in the central area it's movement over the target surface and heats this locally so strongly that the target material evaporates in explosive way, upon which the spark extinguishes. This leads also to an increased emission of neutral particles (splash) and increased target removal in the central area of the target. This course of the spark proves in the practical field also therefore as unfavourable since only a proportionately smaller part of the target surface is removed, which leads to development of erosion profile and that means frequent change in order

to maintain the mechanical stability of the target. Thus only a fraction of the frequently expensive target material can be evaporated before end of target service life.
In Figure 5 the course of the vertical B1 and parallel B11 components of a magnet field as per invention is represented as it as for example, through an arc source described in Figure 1 is generated at the target surface or rather directly in front of it, through super position of two coil fields. Therein the coil currents corresponding to Table 1 were adjusted constant to 1.5 A for the first coil 9 or rather 5A for the second coil 10, instead of (1) and (2) better take the indicaters from Figure 1.
The magnet field generated through it distinguishes itself through a course of the vertical component, which other than in Figure 3 is constant over a wide area and shows clearly smaller values. So the vertical component B1 runs here between +5 and -5 Gauss whereas the vertical component in Figure 3 runs between +80 and -120 Gauss, with a represented minimum in central area. Also the parallel component B11 reprensented in Figure 5 is wholly weaker than that in Figure 3. From a value of about 20 Gauss beginning at the target border B11 runs with a gradient of about 4 Gauss/cm, quasi linear till in the proximity of the turning point (corresponds to a minimum in polar co-ordinates representation). First in this direct surrounding the curve clearly flattens out. The development of one or more number of B1 zero lines in combination with maximum B11- values is therein deliberately avoided through a first coil, whose internal diameter approximately corresponds to the target projection, with which the spark is not forced on a preferred path and the formation of represented

removal profile, like as for example circulating race tracks is avoided. Similar magnet fields can also be generated in known way through permanent magnets.
Figure 6 shows analogous to Figure 4 a vectorial representation of the force working on a spark through an arc source as per invention, as described under Figure 1 at the positions 1-7 of the target surface. This could also explain how an executed or rather operated magnet system as per invention effectively prevents that the spark contracts in damaging way toward the target centre. Through the parallel force components F11 mainly continuously rising out wards the spark receives a relatively constant anguler speed over the total radial area of the target, the spark therefore runs all the more quickly, further it is distanced from the target centre. At the same time the centripetal force components 1 working in the central area is less than that in Figure 4.
In the operation of a such arc source it is observed that it comes to a fine ramification of the arc current in many small sparRs, which flow-off the entire area of the target. Further the magnet field arisen through the superimposition of both the coil fields forms a remote field, which causes a bundling of the plasmas to a plasma - jet, which from it's side can be deflected through additional coils. Since at equal target efficiency the removal is at least likewise large as in conventional arc sources, it comes in alignment of the ion flow in direction of the work piece 3 to a higher coating rate. This bundling can be adjusted corresponding to the requirements in wide extent, as for example through adjustment of coil currents on the respective specially geometric proportion like as for example desired coating height, substrata target distance etc.
Figure 7 and Figure 8 show two further executions of an arc source as per

invention, in doing so in Figure 7 the second magnet system 10 covers the first magnet system 9 while in Figure 8 the second magnet system 10 is assembled before the target 6. In an arc source as shown in Figure 8 the second magnet system can also show similar dimensions like the first system, in particular when first and second system are assembled operation symmetrically against the target and the internal diameters are selected at least equal or greater than the external dimensions of the target.
Figure 9 shows a vacuum treatment plant 1 with arc sources 2, which act sidewise on one or more number of work pieces 3 moved around the installation axle 13. For the vertical deflection of the plasma jet further coils 14 are planned in Helmholtz assembly.
Figure 10 shows a coating installation 1 with 6 arc sources 2 in the cross section in which all sources 2 are aligned mainly right angularly in direction of the installation axle 13.
Figure 11 to Figure 16 show the courses generated in different adjustment of coil current, of B1- or rather B11- components of the magnet field at the target surface. The arc sources were operated therein corresponding to the operating parameters described in Figure 1, in order to determine the optimum adjustment area and limits.
So the Figures 11 and 12 show different, corresponding B1- or rather B1- curves of the magnet field with relevant coil adjustment, in which a desired finely distributed spark course could be attained. Here in it is to be noted, that B1-or rather B11- values in provided geometric configuration can not be adjusted

independent of each other, due to which in each case only one equally described B11- distribution in Figure 12 corresponds to a B1- distribution in Figure 11.
Figure 13 and 14 show a border case, in which the bend infact runs yet finally distributed, but already with free eye first sign of a periodic contractions in the centre, are to be identified. In case the B1- distribution is shifted yet clearly further to negative values it, comes to a coarser spark course and to a too strong contraction in the central area.
Figure 15 and 16 show a further limiting case, Also here the spark pattern is yet sufficiently finelly distributed, however first sign of a periodic pushings of spark in the border area of the target through the magnet field applied herein are to be identified. In case the B1- distribution is shifted yet clearly further to positive values, it comes to a coarser spark course at the border of the target.
It was further found out, that B1- distribution, which lie on both sides of the zero line, allow higher differences of magnet field strength, that means a non- uniform B1- distribution at the target surface, in approximately unchanged fine and evenly distributed spark course than, that B1- distribution which lie fully over or rather under the zero line.

We claim:
1. Vacuum arc source (2) comprising a target (6) with a surface for
operating an arc discharge, wherein the target is arranged in the effective area
of a device producing a magnetic field, characterized in that the device producing
the magnetic field comprises at least two magnet systems (9,10) with opposite
poles and is designed so that the component B± of the magnetic field standing
perpendicular to the surface has substantially constant low values of less than 30
Gauss or zero over a large part of the surface.
2. Arc source as claimed in claim 1, wherein the value of the perpendicular
magnetic field component B± is less than 20, preferably less than 10 Gauss.
3. Arc source as claimed in any preceding claims, the large part of the
surface extends from a middle area of the target surface to an edge zone, such
that the large part includes at least 50%, particularly preferably 60% or more of
the geometrically decisive mass of the target surface.
4. Arc source as claimed in any of the preceding claims, wherein in the edge
zone of the target surface, the values B1R of the perpendicular magnetic field
component rise, fall and/or change signs compared with the values B±M in the
middle area of the target surface.

5. Arc source as claimed In any of the preceding claims, wherein the value of
the parallel magnetic field component B|| is substantially zero in the middle
and rises or falls in the direction of the edge of the target surface, preferably
symmetrically in relation to the target center, particularly preferably rises
substantially linearly.
6. Arc source as claimed in any of the preceding claims, wherein the first of
the at least two magnet systems with opposite poles comprises at least one first
electromagnetic coil placed behind the target.
7. Arc source as claimed in claim 6, wherein the inner dimensions of the first
coil substantially coincide, with a deviation of maximum plus/minus 30%,
preferably plus/minus 20%, with the projection of the outer dimensions of the
surface.
8. Arc source as claimed in any of claims 1 to 5, wherein the first of the at
least two magnet systems with opposite poles comprises one or more permanent
magnets placed behind the target.

9. Arc source as claimed in claim 8, wherein the permanent magnet or
magnets either themselves have low field strength, or have a distance from the
target such that the field strength at the target surface is low.
10. Arc source as claimed in any of the preceding claims, wherein the second
of the at least two magnet systems with opposite poles comprises at least one
second coil arranged coaxially to the first magnet system.
11. Arc source as claimed in claim 10, wherein the second coil (10) is
arranged behind the first magnet system (9).
12. Arc source as claimed in claim 10, wherein the second coil (10) is
arranged at a distance in front of the target.
13. Arc source as claimed in claim 10, wherein the second coil (10) surrounds
the first magnet system (9) at least partly coaxially.
14. Arc source as claimed in claims 10 to 13, wherein the second coil (10) has
a higher number of windings and/or a larger diameter than the first coil.

15. Arc source as claimed in any of the preceding claims, wherein the target
(6) is connected as a cathode.
16. Arc source as claimed in any of the preceding claims, wherein the target
(6) is connected as an anode.
17. Vacuum system in which at least one arc source (2) is arranged as
claimed in any of claims 1 to 16.
18. System as claimed in claim 17, wherein the at least one arc source acts in
the direction of the system axis and has at least one further electromagnetic coil
arranged concentrically to the system axis in order to deflect the plasma beam
produced.
19. System as claimed in claim 18, wherein the at least one further coil is
connected to at least one temporally varying current source with a control unit in
order to deflect variably the alignment of the plasma beam produced by the at
least one arc source.

20. System as claimed in one of claims 18 and 19, wherein at least two
further electromagnetic coils, preferably in the upper and lower or corresponding
laterally adjacent areas of the system, are arranged concentrically to the system
axis and have a different or the same diameter or a design substantially
corresponding to a Helmholz coil arrangement.
21. Method for operating an arc discharge on the target surface of an arc
source (2) using a device producing a magnetic field, characterized in that the
device for producing a magnetic field generates a magnetic field on the surface
such that its perpendicular component Bl over a large part of the surface has a
substantially constantly low value of less than 30 Gauss or zero.
22. Method as claimed in claim 21, wherein the value Bl of the perpendicular
magnetic field component is set less than 30, preferably less than 20, particularly
less than 10 Gauss.
23. Method as claimed in claims 21 and 22, wherein the magnetic field is set
so that the large part of the surface with component Bl running perpendicularly
substantially constantly near or at zero extends from the middle area of the
target surface to an edge zone, such that the middle area comprises at least

60%, particularly preferably 60% or more of the geometrically decisive mass of the target surface.
24. Method as claimed in any of claims 21 to 23, wherein in the edge zone of
the target surface the values B1R of the perpendicular magnetic field component
are set to rise, fall and/or change signs compared with the values B1M in the
middle area of the target surface
25. Method as claimed in any of claims 21 to 24, wherein the value of the
parallel magnetic field component B|| is set substantially at zero in the middle
and rises in the direction of the edge zone of the target surface, preferably
symmetrically in relation to the middle of the target, so that the force acting
tangentially on the spark clockwise or counter-clockwise rises toward the edge
zone of the target.
26. Method as claimed in claims 21 to 24, wherein a magnetic field aligned
substantially perpendicular to the surface is also produced in an area in front of
the target.

27. Method as claimed in any of claims 21 to 26, wherein the magnetic field
strength is set corresponding to the target material and/or target thickness.
28. Method as claimed in any of claims 21 to 27, wherein the device
producing the magnetic field comprises at least one coil placed behind the
target, and a voltage source is applied to at least one coil to adjust the magnetic
field, so that current flows in a first direction.
29. Method as claimed in any of claims 21 to 27, wherein the device for
producing the magnetic field comprises at least one magnet system constructed
from of one or more permanent magnets and arranged behind the target.
30. Method as claimed in any of claims 28 and 29, wherein at least one
second coil is placed behind, in front of or around the target, and to adjust the
magnetic field a voltage is applied to the second coil such that a second
magnetic field is produced that is aligned opposite the magnetic field produced
by the first magnet system.
31. Method for coating a workpiece, in particular a tool and/or a component,
using one of the methods in claims 20 to 29.

32. Method for coating a workpiece, in particular a tool and/or a component, using an arc source as claimed in claims 1 to 16.

ABSTRACT
TITLE: VACUUM ARC SOURCE WITH MAGNET FIELD GENERATING EQUIPMENT
Vacuum arc source (2) comprising a target (6) with a surface for operating an arc discharge, wherein the target is arranged in the effective area of a device producing a magnetic field, characterized in that the device producing the magnetic field comprises at least two magnet systems (9,10) with opposite poles and is designed so that the component B1 of the magnetic field standing perpendicular to the surface has substantially constant low values of less than 30 Gauss or zero over a large part of the surface.
FIG. 1

Vacuum arc source (2) comprising a target (6) with a surface for operating an arc discharge, wherein the target is arranged in the effective area of a device producing a magnetic field, characterized in that the device producing the magnetic field comprises at least two magnet systems (9,10) with opposite poles and is designed so that the component B1 of the magnetic field standing perpendicular to the surface has substantially constant low values of less than 30 Gauss or zero over a large part of the surface.

Documents:

1395-KOLNP-2005-CORRESPONDENCE.pdf

1395-kolnp-2005-granted-abstract.pdf

1395-kolnp-2005-granted-claims.pdf

1395-kolnp-2005-granted-correspondence.pdf

1395-kolnp-2005-granted-description (complete).pdf

1395-kolnp-2005-granted-drawings.pdf

1395-kolnp-2005-granted-examination report.pdf

1395-kolnp-2005-granted-form 1.pdf

1395-kolnp-2005-granted-form 18.pdf

1395-kolnp-2005-granted-form 2.pdf

1395-kolnp-2005-granted-form 26.pdf

1395-kolnp-2005-granted-form 3.pdf

1395-kolnp-2005-granted-form 5.pdf

1395-kolnp-2005-granted-reply to examination report.pdf

1395-kolnp-2005-granted-specification.pdf

1395-kolnp-2005-granted-translated copy of priority document.pdf

1395-KOLNP-2005-PA.pdf

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Patent Number

228115

Indian Patent Application Number

1395/KOLNP/2005

PG Journal Number

05/2009

Publication Date

30-Jan-2009

Grant Date

28-Jan-2009

Date of Filing

19-Jul-2005

Name of Patentee

UNAXIS BALZERS AG.

Applicant Address

FL-9496 BALZERS, LIECHTENSTEIN

Inventors:

#	Inventor's Name	Inventor's Address
1	SCHUTZE, ANDREAS	CHURERSTRASSE 10, A-6800 FELDKIRCH
2	WOHLRAB, CHRISTIAN	WEINBERGGASSE 31A, A-6800 FELDKIRCH

PCT International Classification Number

H01J 37/32

PCT International Application Number

PCT/CH2003/000710

PCT International Filing date

2003-10-30

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	2163/02	2002-12-19	Switzerland