Magnetron cathode having heat sink, and cooling device for a magnetron cathode

Abstract

The invention relates to a magnetron cathode (10) with a plate-shaped heat sink (14) made of metal with a flat upper side (20) and to a cooling device (12) for a magnetron cathode (10). A plate-shaped target (18) is detachably mounted on the heat sink (14), wherein the target (18) is placed with its rear side (40) on the upper side (20) of the heat sink (14). A recess (22) open to the rear side (40) of the target (18) is formed in the upper side (20) of the heat sink (14), in which recess a magnet assembly (24) having one or more magnet elements (28) is arranged. An air gap (42) is arranged between the magnet assembly (24) and the target (18).

Description

[0001] (20208.4)

[0002] Description

[0003] Magnetron cathode with heat sink and cooling device for a magnetron cathode

[0004] The invention relates to a magnetron cathode, such as that used in magnetron sputtering processes, and a cooling device for a magnetron cathode. A target made of a sputtering material is typically attached to a magnetron cathode, which is sputtered by ions in a vacuum. A magnetic assembly serves to deflect electrons so that the ionization is maintained.

[0005] German patent DE 18858 Ai describes a magnetron arrangement with a target, beneath which support elements, a magnet system, and a cooling system with a cooling plate are arranged. To improve the homogeneity of heat transfer, heat transfer occurs primarily in the form of thermal radiation.

[0006] EP 1609880 Ai discloses an atomizing cathode for coating processes in a vacuum chamber, comprising a target plate (at least one piece) mounted on a metallic membrane. On the side of the membrane facing away from the target plate are a coolant channel with an inlet and outlet line for a coolant and a cavity for at least one magnet system. The magnet system is arranged in a support tray sealed against the membrane and is not exposed to the coolant. The entire assembly is mounted on a support structure.To improve heat transfer from the target plate to the coolant in a simple, effective, and cost-efficient manner, and to prevent the risk of coolant ingress into the vacuum chamber, the support structure for the atomizing cathode is designed to have a hollow body that is gas-tightly sealed from the interior of the vacuum chamber and connects the cavity surrounding the magnet system to the atmosphere outside the vacuum chamber. Furthermore, the coolant channel is designed as a conduit closed on its cross-sectional circumference with at least one flat side that is in thermally conductive contact with the membrane. Finally, the membrane and the surfaces of the conduit facing away from the membrane are exposed to the atmospheric pressure outside the vacuum chamber via the aforementioned support structure. (20208.4)

[0007] DE 4201551 Al relates to a sputtering cathode operating on the magnetron principle, comprising a cathode body equipped with a target having a sputtering surface and a circumferential surface. Behind the target, a magnet system with nested poles of opposite polarity is provided to generate magnetic field lines that emerge from the target and re-enter it after traversing arc-shaped paths. The outer edges of the target, located outside the erosion zone, are covered by a dark-space shield extension running parallel to the sputtering surface and having an inner edge. The dark-space shield is electrically floating and separated from the target by a gap large enough to prevent plasma ignition between the target and the dark-space shield, ensuring that only the exposed target is sputtered.

[0008] The task can be seen as proposing a magnetron cathode and a cooling device for it, in which a favorable arrangement of the various components is given, especially with regard to heat transport.

[0009] With regard to the problem, the invention proposes a magnetron cathode according to claim 1 and a cooling device according to claim 16. Dependent claims relate to advantageous embodiments of the invention.

[0010] The magnetron cathode according to the invention comprises at least one plate-shaped heat sink, a plate-shaped target detachably attached to the heat sink and a magnet assembly.

[0011] The plate-shaped heat sink is made of metal, in particular a highly thermally conductive metal such as aluminum or, more preferably, copper, or of an alloy with copper and / or aluminum as the main component. The plate-shaped heat sink has a flat top surface, which is the side facing the target.

[0012] The target is plate-shaped and placed with its back side on the top of the heat sink, so that at least an substantially flat back side of the target is in contact with the flat top of the heat sink. This can (20208-4)

[0013] The contact between the surfaces can be direct, or alternatively, indirect with an intermediate layer, for example, a thin, flexible film that supports the system and heat transfer. The target is detachably attached to the heat sink, for which target mounting devices may be provided. These target mounting devices are preferably clamping elements that press the target firmly against the heat sink to achieve a tight fit and good heat transfer. The clamping elements can be of various designs and may include, for example, one or more clamping devices; preferably, they consist of multiple screw connections.

[0014] The term "plate-shaped" can be understood to mean that the body in question, i.e., the target and the heat sink, is at least substantially planar and has the shape of a flat, wide disk or plate, meaning it extends further in its surface dimensions (length, width) than in its depth (thickness). The thickness of the plate-shaped body is significantly less than its surface dimensions. For example, the thickness can be less than 25% of the shortest surface dimension (i.e., usually the width), preferably less than 20%, and particularly preferably less than 15%. With respect to the largest surface dimension (preferably the length), the thickness is preferably less than 5%, and more preferably less than 3%.

[0015] The plate-shaped bodies are preferably solid, i.e., they preferably have no cavities except for minor recesses such as drill holes (and the described depression). The two plate-shaped bodies are preferably one-piece, i.e., either monolithic, consisting entirely of a single piece, or, if they consist of several joined parts, these are firmly and permanently connected to one another, preferably by a material bond, e.g., by welding, brazing, gluing, bonding, etc. In the case of the plate-shaped heat sink, a monolithic body made of a continuous material is preferred, while—as explained below—the target may preferably consist of several firmly connected parts.

[0016] At least one recess open towards the rear of the target is formed in the top surface of the heat sink, in which a magnetic assembly with one or preferably several magnetic elements is arranged. The recess is preferably formed inside the top surface, i.e., at a distance from the edges. The magnetic elements of the magnetic assembly (20208-4)

[0017] The magnet assembly preferably consists of permanent magnets, in particular preferably samarium-cobalt magnets and / or iron-neodymium-boron magnets. Preferably, the magnet assembly is arranged completely within the recess, i.e., countersunk relative to the top surface of the heat sink.

[0018] According to the invention, an air gap is arranged between the magnet assembly and the target. As will be explained in more detail below, the air gap can be formed, for example, by an arrangement of the magnet assembly recessed by a certain amount in the recess, by a recess in the target, or by both.

[0019] The cooling device according to claim 16 for a magnetron cathode comprises a plate-shaped metal heat sink with a flat top surface for positioning a plate-shaped target. A recess is formed in the top surface of the plate-shaped heat sink, in which a magnetic assembly with one or more magnetic elements is arranged. An air gap is arranged in the recess above the magnetic assembly and below the height of the top surface. When the plate-shaped target is placed on the top surface, the air gap between the magnetic assembly and the target is thus formed.

[0020] The target can be changed on the cooling unit by means of the detachable attachment to the heat sink. The magnetron cathode and the cooling unit according to the invention allow the magnet assembly to be arranged in the immediate vicinity of the changeable target, so that a strong magnetic field can be achieved in the target area. Good heat transfer is ensured by the flat contact of the target on the top of the heat sink. Nevertheless, the air gap between the magnet assembly and the target creates a certain thermal barrier, thus reducing or preventing direct heat conduction from the target to the magnet assembly. In this way, excessive heat stress on the magnet assembly is avoided.

[0021] The recess on the top of the heat sink preferably reduces the contact area between the target and the heat sink; that is, the target and heat sink are not in full contact because there is no contact in the area of ​​the recess. Here, "contact" is understood to mean either direct contact, i.e., direct contact of the bodies with each other, or indirect contact via a (20208-4)

[0022] A thin contact film is inserted between the target and the heat sink. According to a further development of the invention, the plate-shaped target is arranged with a target backing on the top surface of the heat sink, wherein the size of the contact area between the target backing and the top surface of the heat sink is smaller than the area of ​​the target backing. The area of ​​the target backing is preferably considered to be the area lying in a plane. For example, the contact area can be 5–50% smaller than the area of ​​the target backing. Preferably, the contact area is at least 10% smaller than the area of ​​the target backing, more preferably more than 20%, but more preferably less than 40%. The size of the recess on the top surface of the heat sink extends accordingly over an area that corresponds to 5–50% of the area of ​​the target backing, more preferably 10–40%, more preferably 20–40%.

[0023] The surface of the plate-shaped heat sink preferably has a free area, i.e., an area accessible to the target, which corresponds at least substantially (here understood, for example, to + / - 10%) to the area of ​​the target's rear side. Thus, the size of the recess can be chosen such that the aforementioned values ​​for the area fraction also apply to the free area of ​​the heat sink's surface. However, the plate-shaped heat sink can, for example, extend beyond the target in length and / or width, so that the total surface area of ​​the heat sink is larger than the area of ​​the target's rear side. Relative to the total surface area of ​​the heat sink, the size of the area in which the recess is formed is preferably 4–40%, more preferably 5–30%, and particularly preferably 10–25%.

[0024] In the preferred case of pressing the target against the heat sink using a contact medium, a high surface pressure is crucial for close contact (whether direct or indirect via an interposed film). Reducing the contact area due to the recess results in a higher surface pressure for the same force, thus improving heat transfer in the contact area.

[0025] A partial interruption of the contact surface, such as that created by the gap formed in the area of ​​the recess between the top of the heat sink and the back of the target, can be particularly advantageous in the case of deformations of the target or heat sink, such as those that can occur during heating. For example, if the target is made of different materials, it can deform due to (20208-4)

[0026] Different coefficients of thermal expansion of the materials cause deformation (bimetallic effect). In the case of such deformations, which can make full-surface contact impossible, contact formed only in certain spots due to the gap in the area of ​​the depression, but with high surface pressure, can ultimately lead to a higher overall heat transfer than an originally full-surface contact, which is significantly reduced by deformation.

[0027] Preferably, target fastening means can be arranged not only on one side of the recess, but on opposite sides to allow for double-sided pressure. In the preferred case of the recess being formed as a groove (su), the target fastening means are preferably arranged on both sides of the groove; in the further preferred case of a groove formed as a closed track, the target fastening means are preferably arranged both inside and outside the closed track.

[0028] The arrangement and shape of the recess, the target, and the magnet assembly can be chosen differently, so that the air gap has different heights, widths, and orientations relative to the magnet assembly. Preferably, the air gap has a height of, for example, at least 0.5 mm; more preferably, a height of at least 1 mm. More preferably, the air gap has a height of no more than 10 mm; more preferably, no more than 5 mm. The extent of the air gap in the transverse direction, i.e., parallel to the flat top surface of the heat sink, is preferably such that the air gap extends over at least 50% of the upper surface of the magnet assembly; more preferably, over at least 70%; and particularly preferably, over at least 90%.

[0029] The magnetron cathode according to the invention can be implemented in various ways, with different numbers, shapes, and arrangements of recesses on the top of the heat sink. For example, a recess can be a slot that is at least partially continuous or a through hole that completely penetrates the heat sink. However, according to a further development of the invention, it is preferred that the recess has a closed bottom that is recessed relative to the top of the heat sink, i.e., preferably the depth of the recess is less than the height of the heat sink.

[0030] The base is preferably flat and parallel to the top of the heat sink. (20208-4)

[0031] The heat sink is plate-shaped. The recess can have a depth of more than 50% of the thickness of the heat sink, preferably more than 75%. This provides sufficient space for accommodating the magnet assembly and for the air gap.

[0032] According to a preferred embodiment of the invention, the magnetic assembly comprises a plurality of magnetic elements arranged in the recess. The magnetic elements can, for example, be cuboid in shape. They are preferably arranged directly adjacent to one another, i.e., in contact with each other or at most with a very small gap between them. More preferably, a plurality of the magnetic elements are covered on the upper side by a flat, ferromagnetic cover element, e.g., a sheet. The cover element preferably covers several magnetic elements, more preferably the plurality of the magnetic elements, and most preferably all magnetic elements together, and can thus serve to bundle and guide the magnetic flux of the individual magnetic elements. More preferably, a cover element can also be arranged below the magnetic elements, so that the magnetic assembly is formed by magnetic elements arranged between two covering cover elements.

[0033] The air gap can be formed, for example, directly between the magnetic elements and the target, or, in the case of a cover element placed on the magnetic elements, between the cover element and the target. Preferably, the air gap is arranged at least partially within the recess, i.e., the size, in particular the depth, of the recess is selected relative to the size of the magnetic assembly such that the magnetic assembly is preferably recessed to such an extent that sufficient space remains in the recess, i.e., below the top surface of the heat sink, for the air gap.

[0034] The target can be flat in the area opposite the recess, meaning it covers the recess to a height corresponding to the top of the heat sink. However, it is also possible that recesses and / or protrusions are formed on the otherwise flat back of the target. These can be located opposite the recess in the top of the heat sink.

[0035] According to one embodiment of the invention, the plate-shaped target is arranged with its target back side on the top of the heat sink, e.g. in direct (20208-4)

[0036] or indirect contact of the surfaces. At least one recess can be formed in the back of the target, positioned opposite the recess in the top of the heat sink. Such a recess in the back of the target can serve to achieve the desired distance between the target and the magnet assembly, for example, by positioning the air gap at least partially within the recess on the back of the target.

[0037] According to a particularly preferred embodiment, the recess is formed at least partially as a groove. A groove is understood to be an elongated recess that preferably has a substantially constant width and depth. The groove can, for example, run straight or curved on the top surface of the heat sink. Preferably, the groove runs in at least one, preferably two, straight sections, which more preferably run parallel to each other. A groove that forms a closed track on the top surface of the heat sink is particularly preferred. The particularly preferred shape of the track is formed by two parallel, spaced-apart straight sections, each of which is connected at its end by curved sections of the groove to form a closed track.

[0038] The magnetic assembly can be mounted within the recess in various ways. Preferably, the recess has at least one undercut effective towards the top, and at least one, preferably several, and particularly preferably all of the magnetic elements are arranged in the recess in a form-fitting manner such that they lie at least partially beneath the undercut. This ensures good retention and positioning of the magnetic elements and guarantees the position and arrangement of the air gap. If the recess is preferably designed as a groove, this groove can, according to a preferred embodiment, have a receiving area and a holding area arranged above it towards the top of the heat sink, the receiving area being wider than the holding area. Such a cross-sectional shape of the groove can also be described as an inverted T-shape.The holding areas along both edges of the groove create an undercut through which magnetic elements can be held.

[0039] According to a preferred embodiment, magnetic elements of the magnetic assembly can be slidably arranged in the recess, which is preferably designed as a groove (20208.4)

[0040] The magnetic element is preferably displaceable within a guide, such as a rail guide. More preferably, a widened insertion area can be formed at one or more points along the groove, allowing magnetic elements to be inserted into the groove and then moved along the groove so that, after displacement, they are positively engaged under the undercut. A widened insertion area and adjacent undercut areas can be provided for both straight sections of the groove and (preferably annular) curved sections.

[0041] According to a further development of the invention, at least one coolant channel can be arranged on the heat sink, enabling heat transfer away from the heat sink by using a preferably liquid coolant medium. Various possibilities are conceivable for the shape and arrangement of the coolant channel(s), for example, in the form of one or more bores through the heat sink. A coolant channel can, for example, run in loops or meanders below the top surface of the heat sink. A particularly preferred arrangement of the coolant channel is one in which it runs below the top surface and, more preferably, on the underside of the plate-shaped heat sink, but is arranged at least partially opposite the depression formed in the top surface of the heat sink. Preferably, the coolant channel extends over the majority of the depression's extent, i.e.,In the preferred case, the recess is designed as a groove over the majority of its length, preferably over its entire length, and arranged opposite each other. This achieves particularly effective cooling precisely in the area of ​​the recess where the magnet assembly is located. This further contributes to limiting the temperature of the magnet assembly.

[0042] According to a preferred embodiment, the coolant channel has a wall and an interior space, the interior space serving for the passage of the coolant. The wall can completely enclose the interior space, which may, for example, have a rectangular cross-sectional shape. Preferably, however, the wall has an open cross-section and is arranged on the flat underside of the heat sink such that the cross-section is closed by the underside, with a portion of the underside being in contact with the interior space. In this way, the material of the heat sink is cooled directly by the coolant without an intervening wall. (20208.4)

[0043] In a preferred embodiment, the heat sink and the target each have an elongated, rectangular shape. The dimensions can vary depending on the embodiment. The width of the target can preferably be, for example, between 30 and 200 mm, more preferably 50–100 mm. The length of the target can preferably be, for example,

[0044] The length may be 250–1500 mm, preferably 400–1000 mm. In the preferred elongated shape, the length can be, for example, more than three times the width, preferably five times or more.

[0045] The heat sink and the target can have at least substantially the same dimensions (i.e., with a maximum deviation of + / - 5% in length and / or width). Preferably, the heat sink is larger in length and / or width than the target, so that, for example, a frame can be mounted on it, surrounding the target. For this purpose, the width of the heat sink can be, for example, 20–80% greater than the width of the target, more preferably 40–60%. Similarly, the length of the heat sink can be, for example, 3–20% greater than the length of the target, more preferably 5–10%.

[0046] The recess, preferably designed as a groove, comprises at least a first and a second groove section that run parallel to each other in the longitudinal direction of the heat sink. The straight first and second groove sections are preferably connected to each other by curved sections of the groove to form a closed track. Preferably, at least one first and one second coolant channel section are arranged on the heat sink. The coolant channel sections preferably run straight and parallel to the first and second groove sections. This enables efficient cooling, particularly in the area of ​​the recess (groove).

[0047] Embodiments of the invention are described in more detail below with reference to the drawings. These drawings show

[0048] Fig. 1 shows a magnetron cathode in perspective view;

[0049] Fig. 2 shows the magnetron cathode from Figure 1 in a perspective exploded view;

[0050] Figs. 3, 4 show a cooling device for the magnetron cathode from Figs. 1, 2 with the target attached, in perspective view from the top and bottom; (20208.4)

[0051] Fig. 5 shows the cooling device and the target from Figures 3 and 4 in a perspective exploded view;

[0052] Fig. 6: a cross-section through the cooling device and the target along line A .. A in Figure 3;

[0053] Fig. 7: the cooling device from Fig. 5 (without target) in top view;

[0054] Fig. 8: schematic representation from above of a coating system with magnetron cathodes arranged therein;

[0055] Fig. 9: analogous to Figure 6, a cross-section through an alternative embodiment of a magnetron cathode.

[0056] Fig. 1 shows in perspective view a magnetron cathode 10 with a housing 11 and a target 18 held in the housing 11, exposed at the top.

[0057] Fig. 2 shows the magnetron cathode 10 in a perspective exploded view. The magnetron cathode 10 comprises a cooling device 12 arranged in the housing 11, with a plate-shaped heat sink 14 and coolant channels 16 with coolant connections 17 arranged below it. A frame 11b is mounted on the upper surface 20 of the heat sink 14. Within the frame 11b, the plate-shaped target 18 is arranged on the upper surface 20 of the heat sink 14 against the cooling device 12 and is screwed to the heat sink 14 by means of target screws 19 and pressed against it.

[0058] In the preferred embodiment shown, the plate-shaped target 18 is rectangular and can have different dimensions in length and width, depending on the specific embodiment. In the preferred embodiment shown, the length of the target is approximately 500 mm and the width of the target 18 is approximately 90 mm. In an alternative embodiment (not shown), the target 18 can, for example, have a greater length of 800 mm while maintaining the same width.

[0059] The plate-shaped heat sink 14 is larger in length and width than the plate-shaped target 18 by the width of the frame 11b (approximately 20 mm) and by a certain distance of a few mm between the frame 11b and the target 18. In the example shown, the length of the heat sink 14 is approximately 10% greater than the length of the target 18, and the width of the heat sink 14 is approximately 50% greater than the length of the target 18. (20208.4)

[0060] Figures 3 and 4 show perspective views of the cooling device 12 with the target 18 placed on it, from the front and back, and Figure 5 shows the cooling device 12 and the target 18 in a perspective exploded view. As can be seen there, a recess in the form of a groove 22 is arranged on the surface 20 of the cooling body 14. The groove 22 forms a closed track inside the surface 20 of the cooling body, i.e., spaced apart from its edges.

[0061] In the groove 22 a magnetic assembly 26 is arranged with a plurality of separate, predominantly cuboid magnetic elements 28, an upper ferromagnetic cover plate 30 and a lower ferromagnetic cover plate 32.

[0062] Figure 6 shows a cross-sectional view of the cooling device 12 with the target 18 attached. The groove 22 is formed as a recess in the surface 20 of the heat sink 14, but does not penetrate it completely, leaving a groove base. The groove 22 has a constant depth, which in the illustrated example corresponds to approximately 90% of the thickness of the heat sink 14. The groove 22 has a T-shaped cross-section, in which the protruding edges on both sides form an undercut 34 relative to a wider, underlying inner area of ​​the groove 22. The magnetic elements 28 of the magnetic assembly 26 are positively engaged in the groove 22, partially below the undercuts 34 thus formed, so that their position is fixed in the thickness direction of the heat sink 14.

[0063] The target 18, shown in simplified form (i.e., without plugs, drill holes, or screws) in Figure 6, comprises a target plate 36 and a base plate 38. The target plate 36 is made of sputtering material. For the sake of simplicity, it is shown in Figure 6 as a single, solid body, but depending on the composition required for the sputtering process, it can also be made of multiple parts, in particular with plugs (see Figures 1-5) made of different materials inserted into bores. The base plate 38 is firmly bonded to the target plate 36. The base plate 38 is preferably made of copper and serves to establish good, precisely defined thermal and mechanical contact between the target 18 and the cooling device 12.

[0064] The Target 18 is completed on the back, i.e. the bottom side in Figure 6 (20208-4)

[0065] through the flat rear surface 40 of the base plate 38.

[0066] The target 18 is interchangeably mounted on the cooling unit 12; that is, it can be attached to or detached from the cooling unit 12 by tightening or loosening the screw connections formed by the target screws 19. The target screws are distributed across the surface of the target, specifically at the corners as shown, and in a central row in the center. Tightening the target screws 19 presses the target 18 firmly against the heat sink 14.

[0067] As shown in Figure 6, when the target 18 is attached to the cooling device 12, the rear surface 40 of the target 18 and the surface 20 of the heat sink 14 are in direct contact. As shown, the metallic materials of the heat sink 14 and the target 18 (more precisely, the base plate 38) can be in direct contact with each other. In alternative embodiments (not shown), it is also possible to position an intermediate layer, in particular a contact film, between the surface 20 of the heat sink 14 and the rear surface 40 of the target 18, which enables good heat transfer and close contact.

[0068] Although the flat surfaces of target 18 and cooling device 12—i.e., as shown in Figure 6, the flat back surface 40 of target 18 and the flat surface 20 of the heat sink 14—are in contact with each other, the contact is not full-surface. This is because the depth of the groove 22 and the height of the magnet assembly 26 within it are dimensioned such that an air gap 42 remains between the magnet assembly 26 and the back surface 40 of target 18. In the illustrated example, the air gap 42 does not cover the entire width of the groove 22 due to the protruding edges; however, the width of the air gap 42 corresponds to approximately 90% of the width of the groove 22. Therefore, due to the air gap 42, the magnet elements 28 in the groove 22 are not in contact with the target 18, or at least not in full-surface contact, so that the heat transfer from target 18 to the magnet elements 28, which is based on direct heat conduction through the metal body, is limited.

[0069] Due to the groove 22, the size of the contact area between the back 40 of the target 18 and the surface of the heat sink 14 is smaller than the area of ​​the target's back 40. In the example shown, the groove 22 is dimensioned such that the Con- (20208-4)

[0070] The contact area is reduced by approximately 30% compared to the area of ​​the target's rear side 40; that is, the groove 22 is dimensioned such that it extends over an area on the surface 20 of the heat sink 14 that corresponds to approximately 30% of the area of ​​the target's rear side 40. While the free portion of the surface 20 of the heat sink 14, i.e., the portion not covered by the frame 11b, is approximately the same size (i.e., length and width) as the target 18 (possibly with the exception of a small clearance), the total surface 20 of the heat sink 14, as can be seen from the drawings, is larger than the target 18 and extends laterally beyond the target by the width of the frame 11b, so that the area fraction of the groove 22 to the total surface 20 of the heat sink 14 is somewhat smaller. Thus, in the example shown, the groove 22 is dimensioned such that it occupies an area on the surface 20 of the heat sink 14 which is approximately 30% of the free area of ​​the heat sink 14, but only approximately17% of the total surface area of ​​the heat sink 14 corresponds to surface area 20.

[0071] The screw connection of target 18 and heat sink 14 by means of the screws 19 ensures that the back of the target 40 is pressed against the surface 20 of the heat sink 14 with high force. By reducing the contact area, the surface pressure increases, so that a particularly close contact and good heat transfer is achieved on the remaining contact area.

[0072] The coolant channels 16 are arranged on the underside 44 of the heat sink 14. Each of these comprises a wall 46 with a cross-section open towards the underside 44 of the heat sink 14, so that a rectangular interior space 48 is formed in the example shown, through which coolant supplied and discharged via the coolant connections can flow, and which then comes into direct contact with the underside 44 of the heat sink 14.

[0073] The coolant channels 16 run parallel to the course of the groove 22 in such a way that they are directly opposite the groove 22 with respect to the underside 44 of the heat sink 14.

[0074] The path of the groove 22 and the arrangement of the magnetic elements 28 therein are evident from Figure 7, which shows a top view of the cooling device 12, but without the upper cover plate 30 of the magnetic assembly 26. As shown, the path of the groove 22 comprises two parallel straight sections 50 spaced apart from each other in the longitudinal direction of the rectangular shape of the cooling body 14 and two of these in (20208-4)

[0075] Transverse direction curved connecting partial ring sections 52.

[0076] To insert the magnetic elements 28 under the undercut 34 (see Figure 4) of the groove 22, they are inserted individually and then moved so that they are secured under the undercut 34 or the projection. Widened areas 54 are provided at the curved sections 52, where the magnetic elements are inserted and then moved along the path of the groove 22 so that they are secured under the undercut 34 or the projection.

[0077] Figure 8 schematically shows a possible application of the magnetron cathodes 10 in a magnetron sputtering system 60. Substrates 64 to be coated are arranged on rotating holders of a rotating substrate table 66 in a vacuum chamber 62. Several magnetron cathodes 10, four in this example, are arranged in the chamber 62 such that the respective front faces of their targets 18 are oriented towards the substrate table 66. During operation of the magnetron sputtering system 60, a vacuum is generated inside the vacuum chamber 62 by means of a vacuum system 68, and suitable process gases are supplied through a process gas supply 70. By applying an electrical voltage to the magnetron cathodes 10, a plasma is ignited inside the chamber 62, the positive ions of which are accelerated onto the surface of the targets 18 and thereby sputter them.

[0078] The heat generated in this process heats up the targets 18. To limit this, heat is dissipated via the cooling devices 12.

[0079] The arrangement described above, in which an air gap 42 remains between the magnet assembly 26 and the target 18, limits the heat input into the magnet elements 28. Furthermore, the heat sink 14 is effectively cooled in the area of ​​the groove 22 by the coolant channels 16 arranged directly opposite it, which also reduces the temperature load on the magnet assembly 26.

[0080] Figure 9 shows a magnetron cathode 100 according to an alternative embodiment. The magnetron cathode 100 largely corresponds to the magnetron cathode 10 according to the embodiment described above. Only the differences are referred to below. Thus, in Figure 9, the same reference numerals are used for element- - lö (20208-4)

[0081] te used, which are identical in both embodiments.

[0082] In the alternative embodiment of Figure 9, the groove 22 is less deep than the groove 22 in the embodiment according to Figures 1-7. The magnet assembly 26 is arranged completely within the groove 22 as in the previous embodiment, but it essentially fills it completely, so that the top of the upper cover plate 30 lies approximately in a plane with the surface of the heat sink 14.

[0083] The target 18 has a recess in the form of a groove 156 on its rear surface 40 (more precisely: on the rear surface of the base plate 38), which follows the groove 22 in its course and, if the target 18 is appropriately arranged on the cooling device, is located directly opposite the groove 22.

[0084] In the alternative embodiment of Figure 9, an air gap 42 is also located between the magnet assembly 26 and the target 18; however, in this case, it is arranged at least partially on the back side 40 of the target 18 within the groove 156. Here, the air gap 42 covers the full width of the groove 22.

[0085] The embodiments shown are examples and are not to be understood as limiting. Further embodiments may differ in various respects; for example, starting from the alternative embodiment of Figure 7, the depth of the groove 22 and the arrangement of the magnet assembly 26 therein may be selected such that the air gap 42 lies partly within the groove 22 and partly within the groove 156. (20208-4)

[0086] Reference symbol list

[0087] 10, 100 Magnetron cathode 50 Straight sections of the groove 11 Housing 52 Curved sections of the groove 11a Underside 54 Widened areas 11b Frame 60 Magnetron sputtering system 12 Cooling system 62 Vacuum chamber

[0088] 14 heat sinks 64 substrates

[0089] 16 coolant channels 66 substrate table

[0090] 17 coolant connections 68 vacuum system

[0091] 18 Target 70 Process gas supply 19 Target- Very clean 156 Recess / groove in the back of the target 20 Surface of the heat sink

[0092] 22 Nut

[0093] 26 Magnet assembly

[0094] 28 magnetic elements

[0095] 30 Upper cover plate

[0096] 32 Lower cover plate

[0097] 34 Overhang / Undercut

[0098] 36 Target plate

[0099] 38 Base plate

[0100] 40 Rear surface of the

[0101] Targets

[0102] 42 air gap

[0103] 44 Underside of the heat sink

[0104] 46 Wall of the coolant channels

[0105] 48 Interior of the coolant channels

Claims

(20208.4) Claims 1. Magnetron cathode (10), with a plate-shaped heat sink (14) made of metal with a flat top (20), and a plate-shaped target (18) which is detachably attached to the heat sink (14), wherein the target (18) is placed with a rear side (40) of the target (18) on the top side (20) of the heat sink (14), wherein a recess (22) open to the rear (40) of the target (18) is formed in the top (20) of the heat sink (14), in which a magnet assembly (24) with one or more magnet elements (28) is arranged, wherein an air gap (42) is arranged between the magnet assembly (24) and the target (18).

2. Magnetron cathode according to claim 1, wherein the recess (22) extends on the top side (20) of the heat sink (14) over an area corresponding to 5 - 50% of the area of ​​the target rear side (40), preferably 10 - 40%, more preferably 20 - 40%.

3. Magnetron cathode according to one of the preceding claims, wherein the plate-shaped target (18) is arranged with a target back side (40) on the top side (20) of the heat sink (14), wherein the size of a contact area between the target rear (40) and the top (20) of the heat sink (14) is 5 - 50% of the size of the area of ​​the target rear (40).

4. Magnetron cathode according to one of the preceding claims, wherein the recess (22) has a closed bottom recessed relative to the top (20) of the heat sink (14).

5. Magnetron cathode according to one of the preceding claims, wherein the magnet assembly (24) comprises a plurality of magnetic elements (26) arranged in the recess (22). (20208.4) 6. Magnetron cathode according to claim 5, wherein a majority of the magnetic elements (26) in the direction of the top (20) are covered by a flat, ferromagnetic cover element (30) and the air gap (42) is arranged between the cover element (30) and the target (18).

7. Magnetron cathode according to one of the preceding claims, wherein the recess (22) has an undercut (34) effective in the direction of the top (20) and at least one magnetic element (26) is arranged in the recess (22) in a form-fitting manner such that it lies at least partially under the undercut (34).

8. Magnetron cathode according to one of the preceding claims, wherein the recess is formed at least sectionally as a groove (22).

9. Magnetron cathode according to claim 8, wherein the groove (22) forms a closed track on the top (20) of the heat sink (14).

10. Magnetron cathode according to one of the preceding claims, wherein the air gap (42) has a height of at least 0.5mm and at most 10mm.

11. Magnetron cathode according to one of the preceding claims, wherein the air gap (42) is arranged at least partially within the recess (22).

12. Magnetron cathode according to one of the preceding claims, wherein the plate-shaped target (18) is arranged with a target rear side (40) on the top side (20) of the heat sink (14), and at least one recess (156) is formed on the target reverse side (40), wherein the recess (156) on the target rear side (40) is arranged opposite the recess (22) in the top side (20) of the heat sink (14), (20208-4) that the air gap (42) is at least partially arranged in the recess (156).

13. Magnetron cathode according to one of the preceding claims, wherein at least one coolant channel (16) is arranged on the heat sink (14), the coolant channel (16) being arranged at least sectionally opposite the recess (22).

14. Magnetron cathode according to claim 13, wherein the coolant channel (16) has a wall (46) and an interior (48), wherein the wall (46) forms an open cross-section, and wherein the wall (46) of the coolant channel (16) is arranged on a flat underside (44) of the heat sink (14) such that part of the underside (44) is in contact with the interior (48).

15. Magnetron cathode according to one of the preceding claims, wherein the heat sink (14) and the target (18) have an elongated, rectangular shape, and the recess (22) has at least a first and a second straight groove section, wherein the first and second groove sections run parallel to each other at a distance from each other in the longitudinal direction of the heat sink (14).

16. Cooling device (12) for a magnetron cathode (10), with a plate-shaped heat sink (14) made of metal with a flat top surface (20) for the detachable attachment of a plate-shaped target (18) such that the target (18) is placed on the top surface (20) of the heat sink (14), wherein a recess (22) open to the top surface (20) is formed in the top surface (20) of the plate-shaped heat sink (14), in which a magnet assembly (24) with one or more magnet elements (28) is arranged, wherein an air gap (42) is arranged in the recess (22) above the magnet assembly (24) and below the height of the top surface (20).

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