DE102011077297A1 - Magnetron sputtering device comprises a target and a magnetic system that are movable with respect to each other - Google Patents

Abstract

Magnetron sputtering device (1) comprises a target (2) and a magnetic system (3) that are movable with respect to each other and the magnet system form a magnetic field penetrating the target, for producing rotating race tracks. The magnetic field lines (4) run asymmetrically over a surface of a target material (22) in the reversal region of the race tracks relative to the normal direction of the surface of the target material.

Description

The invention relates to a magnetron sputtering device.

A magnetron uses a magnet system to concentrate electrons in a plasma zone. This plasma zone is designed so that it is self-contained and can circulate electrons therein (racetrack). Within the racetrack, atoms of the working gas are ionized by the electrons and accelerated to the cathode. The ions knock out the atoms of the target material (= cathode material), which in turn condense as a layer on the substrate.

In planarmagnetrons a magnet system is arranged below the planar target, which is mounted either stationary or parallel to the target surface, so that this movement of the magnet system dynamically sweeps over different areas of the target surface, whereby the magnetic field forming above the target surface and thus also the removal of the magnetic field Target material migrates. Particularly in the case of movable magnet systems, the strongest removal of target material takes place in the regions in which the racetrack runs exactly or approximately in the direction of movement of the magnet system.

In tubular magnetrons, the cathode and thus the target material rotate around a stationary magnet system or a movable, for example rotating magnet system is moved inside the target. The magnetic field generated by the magnetic system forms a racetrack over the surface of the target material, which runs essentially in two straight tracks along the target tube.

At the ends are the deflection zones of the magnetic field in order to achieve a closed form of the racetrack. Along the straight tracks, due to the rotation of the target or magnet system, uniform material removal during the operating period is achieved. At the deflection zones of the magnetic field generated by the magnetic system, the material removal is typically enhanced. In this region at the end of the target tube, the electrons do not move along the target tube transverse to the direction of rotation of the target, but at one end of the target tube in the direction of rotation (circumferential direction) and at the other end of the target tube opposite to the direction of rotation (circumferential direction). Here, the erosion effect accumulates during the operating period and produces a greater material removal than in the straight area of the racetrack.

The service life of a target is terminated when the target material has been completely removed at one point of the pipe. Due to the increased erosion effect, this condition is reached at the ends of the target tube rather than in the central region of the target tube. This leaves a substantial portion of the target material unused, the degree of target utilization is not optimal.

This effect was countered, for example, with a thickening of the target material. i.e. the target ends are provided with additional material (= dog bone targets) to extend the service life of the target. In general, this design achieves a longer service life and an acceptable degree of target utilization. The execution of tube targets in dog bone form is generally associated with low added costs for sprayed targets. For cast or ceramic targets, however, the production is more complex and therefore often not economical. In the latter case straight target tubes, i. Targets with constant thickness of the target material, used. In order to improve target utilization, appropriate measures must be taken to minimize erosion in the curve area.

A general solution is to shift the position of the point of reversal of the racetrack on the target in operation by a dynamic mechanical displacement of the magnet system forming the end of the magnet system, whereby the area in which target material is abraded above average also shifts. Corresponding solutions have already been published. An automatic adjustment can be realized only very complex, a manual adjustment requires the interruption of the production cycle. These variants require interference with the closed and sealed system formed by the target and magnet system.

To remedy the above difficulties, it is now proposed to form the magnetic field so that the magnetic field lines are asymmetric over the surface of the target material, i. the field lines intersect the surface of the target material at the exit site and the entry site at different angles.

There is therefore proposed a magnetron sputtering apparatus comprising a target and a magnet system, wherein the target and magnet system are movable relative to each other and the magnet system forms a target magnetic field for generating a circumferential racetrack, and wherein the magnetic field lines over the surface of the target material in the inverse of the Racetracks run asymmetrically relative to the normal direction of the target surface, so that the area of the target surface, is removed in the target material above average intensity, during operation of the Magnetronsputterereinrichtung shifts with decreasing target thickness. In this case, the field lines of the magnetic field forming are respectively viewed in a sectional plane which corresponds to a vertical section through the magnet system along the shortest connecting line between the two magnetic poles.

In known magnet systems that form a magnetic field for a circumferential racetrack over the target surface, the field lines are symmetrical, i. their base points on the target subtend the same angle with the target surface, and from these base points, the two branches of a field line merging into each other at their point furthest from the target surface are symmetrical to a field normal that is perpendicular to the target surface.

By contrast, in the solution proposed here, the field normal, which forms the axis of symmetry of a field line under consideration, is inclined on the target surface, for example at an angle between 5 ° and 60 ° to the normal direction of the target surface. As a result, the magnetic field in the reverse region of the racetrack is, as it were, "tilted" with respect to the target surface, so that the field line in question encloses different angles with the target surface at its two base points. The result is an oblique erosion direction, i. an erosion direction that deviates from the normal direction of the target surface.

As a result, the position of the maximum of the magnetic flux density on the target surface shifts with decreasing target thickness, so that the area in which the target material is removed above average is also shifted during operation, but without individual ones Magnets must be moved mechanically. This increases the useful life of the target.

This can be achieved, for example, in that the magnets of the magnet system arranged in the target tube or under the planar target, in the end region, i. in the reverse area of the racetrack, be arranged diagonally. This can be realized either by having the magnets below the target material, i. are arranged inside the racetrack and are aligned to an end region thereof, so that the reverse region of the racetrack migrates away from the edge of the target material with decreasing thickness of the target material, or the magnets are arranged at the edge of the target material, in extreme cases outside the racetrack, and towards the middle Aligned so that the reverse portion of the Racetracks migrates with decreasing thickness of the target material on the edge of the target material.

In this case, the obliquely arranged magnets can be arranged either equidistant from the bottom or inside of the target or the obliquely arranged magnets are arranged relative to each other so that their ends facing the target lie in a plane, so that the further from the bottom or inside of the target are removed, the closer they are located at the end of the magnet system.

It can further be provided that the angle at which the magnets are arranged is adjustable. According to a development, the adjustability of the angle at which the magnets are arranged can be effected by an adjusting device which in a further embodiment depends on the elapsed time or / and on the relative movement between the target and the magnet system, i. depending on the revolutions of the target tube (in tube targets with fixed magnet system) or the paths covered by the magnet system (in the case of planar targets with a movable magnet system), the position of the magnets is changed.

Alternatively, the magnets of the magnet system in the reverse region of the racetrack can be arranged in a known manner straight, but provided with oblique magnetization. Likewise, an embodiment is included in which magnets are arranged obliquely and / or angularly adjustable with oblique magnetization, as already described above.

This causes the location of the racetrack turning point to change as the thickness of the target material decreases, i. E. the turning point of the racetrack "migrates" on the surface of the target the thinner the remaining layer of the target material becomes. This makes it possible to move without additional intervention, the place of the strongest erosion and thus to achieve a more uniform removal of target material and an overall higher utilization of the target material.

In a further embodiment, it is provided that the magnet or magnets are held on a plate arranged obliquely relative to the rear or inner side of the target, wherein it may further be provided that the angle of this plate is adjustable.

The one or more magnets in the end region of the magnet system can, for example, have a parallelogram or trapezoidal cross-section. In this case, the magnet or magnets in this area may have inclined side surfaces.

The advantageous asymmetric arc lines of the magnetic field could also be achieved by additional magnetic fields or by additional ferromagnetic elements, if they are able to influence the intended for the Racetrack magnetic field. The use of electromagnetic means is to be weighed in terms of compatibility with sputtering processes.

The invention will be explained in more detail with reference to embodiments and accompanying drawings. Show

1 a known magnetron sputtering device,

2 a magnetron sputtering device according to a first embodiment,

3 a magnetron sputtering device according to a second embodiment,

4 a magnetron sputtering device according to a third embodiment,

5 a magnetron sputtering device according to a fourth embodiment.

In 1 are a magnet system 3 of the type described in a plan view and a longitudinal section through a known magnetron sputtering device 1 in which the magnet system 3 inside a target 2 is arranged, which is a support tube 21 and target material attached thereto 22 includes, shown in longitudinal section. In this conventional magnet system 3 are the magnets perpendicular to the surface of the target material 22 extending polarization, thereby increasing the magnetic field lines 4 perpendicular to the magnets of the magnetic bars 33 and the tails 34 emerge and therefore the surface of the target material 22 cut at both feet on the target surface at the same angle. The field lines 4 are symmetrical to an axis of symmetry 41 aligned with the normal direction of the surface of the target material 22 coincides. The erosion direction is therefore perpendicular to the surface of the target material 22 , which leads to the undesirable effect described.

In the illustrated magnet system 3 are on a coupling plate 32 three elongated magnetic bars 33 arranged parallel to each other, wherein the inner magnetic bar 33 has a magnetization in which the free top is the magnetic south pole and the coupling plate 32 connected base the magnetic north pole. The two outer, on both sides of the inner magnet rod 33 arranged magnetic bars 33 are oppositely magnetized, so that in each case between an outer and the inner magnet rod 33 forms a tunnel-shaped magnetic field. It is understood that the magnetic bars 33 not necessarily be made in one piece, but each may be composed of several magnets.

To connect these two tunnel-shaped magnetic fields to a closed racetrack are at the ends of the magnetic bars 33 two tails 34 arranged like the two outer magnetic bars 33 are magnetized and one end of the two outer magnetic bars 33 connect together so that they form the deflection of the racetrack. It is understood that also the tails 34 not necessarily be made in one piece, but each may be composed of several magnets.

In the interior of the tubular embodiment in the rotatable target 2 is the magnet system 3 on a carrier device 31 arranged one parallel to the longitudinal axis of the target 2 extending support tube, on which the coupling plate 32 is attached by means of clamps, which in turn the magnetic rods 33 and the tails 34 wearing.

A concrete practical implementation of the proposed solution, for example, by redesigning the end pieces 34 respectively. The magnets that often make up the magnetic bars 33 and the tails 34 are formed, for example, thereby bring in an oblique arrangement by the end portions of the coupling plate 32 arranged obliquely or are adjustable in an oblique position or the surface of the coupling plate 32 in the end areas, for example, with notches or oblique supports are made or the magnets are parallelogram in cross section, etc. ..

2 shows an end portion of such a magnet system 3 in which the magnets which are parallelogram-shaped in cross-section are in the reverse region of the racetrack relative to the inside of the target 2 are aligned obliquely, so that the magnetic field lines 4 based on the surface of the target material 22 emerge obliquely from the magnets and therefore the surface of the target material 22 cut at different angles. The symmetry axis 41 the field lines 4 stands obliquely on the surface of the target material 22 ie the axis of symmetry 41 closes with the normal direction of the surface of the target material 22 a non-zero angle and the field lines 4 are based on the normal direction of the surface of the target material 22 , asymmetrical. This shifts the intersections of the field lines 4 with the surface of the target material 22 with decreasing thickness of the target material 22 away from the edge of the target material so that the extension of the racetrack in the longitudinal direction of the target 2 decreases with time. The inside of the target 2 facing surfaces of the tails 34 forming magnets are in this embodiment in a plane with the magnetic rods 33 ,

As with all embodiments described herein are the tail 34 forming magnets are arranged inside the Racetracks and aligned to an end portion thereof, so that the reverse portion of the Racetracks with decreasing thickness of the target material 22 from the edge of the target material 22 Walks away, ie the Racetrack gets shorter with time. However, these representations are to be regarded as purely exemplary. Of course, it would be just as possible in the context of the invention in all described embodiments, the tail 34 to arrange forming magnet on the edge or outside of the Racetracks and align to the central region thereof, so that the reverse portion of the Racetracks migrates with decreasing thickness of the target material on the edge of the target material, whereby the Racetrack becomes longer with time.

3 shows a configuration with obliquely arranged, trapezoidal in cross-section magnets in the tail 34 , whose the inside of the target 2 facing surfaces also oblique, ie non-parallel to the inside of the target 2 are formed. Also the end area of the inner magnetic bar 33 is beveled, so that in the reverse region of the racetrack, the magnetic poles forming magnetic field the same average distance to the inside of the target 2 exhibit. Here, too, is the axis of symmetry 41 the field lines 4 obliquely on the surface of the target material 22 ie the axis of symmetry 41 closes with the normal direction of the surface of the target material 22 a non-zero angle and the field lines 4 are based on the normal direction of the surface of the target material 22 , asymmetrical.

In contrast, in 4 an embodiment shown in which rectangular in cross-section magnets of the tail 34 on a relative to the inside of the target 2 obliquely arranged end portion of the coupling plate 32 are arranged. This end region of the coupling plate 32 can also be made pivotable and adjustable in angle by an adjustment to the angle of inclination of the magnets of the tail 34 to be able to adjust during operation of the magnetron sputtering device.

5 Finally, an embodiment in which the magnets of the tail 34 as in conventional magnetron sputtering devices (see 1 ) are arranged. However, these magnets are magnetized obliquely here, so that here too the axis of symmetry 41 the field lines 4 obliquely on the surface of the target material 22 is, ie the axis of symmetry 41 closes with the normal direction of the surface of the target material 22 a non-zero angle and the field lines 4 are based on the normal direction of the surface of the target material 22 , asymmetrical.

LIST OF REFERENCE NUMBERS

1

magnetron

2

target

21

support tube

22

target material

3

magnet system

31

support means

32

coupling plate

33

magnetic rod

34

tail

4

field lines

41

axis of symmetry

Claims (11)

Magnetron sputtering device ( 1 ) comprising a target ( 2 ) and a magnet system ( 3 ), where Target ( 2 ) and magnet system ( 3 ) are movable relative to each other and the magnet system ( 3 ) the target ( 2 ) forms penetrating magnetic field for generating a circumferential racetrack, characterized in that the magnetic field lines ( 4 ) over the surface of the target material ( 22 ) in the reverse region of the racetrack relative to the normal direction of the surface of the target material ( 22 ) run asymmetrically. Magnetronsputterereinrichtung according to claim 1, characterized in that at least one magnet of the magnet system ( 3 ) is straight in the reverse region of the racetrack and has an oblique magnetization. Magnetronsputterereinrichtung according to claim 1, characterized in that at least one magnet of the magnet system ( 3 ) is arranged obliquely in the reverse region of the Racetracks. Magnetronsputterereinrichtung according to claim 3, characterized in that the at least one magnet is arranged in the interior of the Racetracks and aligned to an end portion thereof, so that the reverse portion of the Racetracks with decreasing thickness of the target material ( 22 ) from the edge of the target material ( 22 ) walks away. Magnetronsputterereinrichtung according to claim 3, characterized in that the at least one magnet is arranged on the edge or outside the Racetracks and aligned to the central region thereof, so that the reverse portion of the Racetracks with decreasing thickness of the target material ( 22 ) on the edge of the target material ( 22 ) to migrate. Magnetronsputterereinrichtung according to any one of claims 3 to 5, characterized in that at least two obliquely arranged magnets with the same distance to the bottom or inside of the target ( 2 ) are arranged. Magnetronsputterereinrichtung according to claim 3 or 4, characterized in that at least two obliquely arranged magnets are arranged relative to each other so that their the target ( 2 ) facing ends in a relative to the surface of the target material ( 22 ) inclined plane lie. Magnetronsputterereinrichtung according to one of claims 1 to 7, characterized in that the angle at which the at least one magnet relative to the surface of the target material ( 22 ) is arranged, is adjustable. Magnetronsputterereinrichtung according to claim 8, characterized in that the magnet system ( 3 ) an adjusting device for adjusting the angle at which the at least one magnet relative to the surface of the target material ( 22 ) is arranged. Magnetronsputtereinrichtung according to claim 9, characterized in that the adjusting device, the at least one magnet depending on the elapsed time and / or depending on the relative movement between the target ( 2 ) and magnet system ( 3 ) adjusted. Magnetronsputterereinrichtung according to one of claims 1 to 10, characterized in that the at least one magnet on a relative to the surface of the target material ( 22 ) obliquely arranged end portion of the coupling plate ( 32 ) is arranged.

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