tube target

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[0001] The invention relates to a target for a Cathode sputtering system with a tubular target body.

[0002] a sputtering source for a target is to be understood under Cathode sputtering system. When cathodic sputtering target material is "atomized" and by means of plasma deposited on a substrate as a thin layer. The cathode sputtering is usually also called sputtering, the sputtering sources sputtering target. A target with a tubular target body is also referred to as a sputtering target in tubular form and is therefore Tube target. A most frequently used is the sputtering magnetron sputtering. While in simple cathode sputtering only an electric field is applied, a magnetic field is generated when magnetron sputtering in addition. Through the superposition of the electrical field and the magnetic field of the path is extended and the number of strokes per electron of the charge carriers increases. The magnetic field is typically generated by a magnet or an arrangement of several magnets is introduced inside the tube targets.

[0003] One advantage of tubular target and thus a higher occupancy rate (tube targets) with respect to planar target is the more uniform removal of material. No understanding the sputtered mass of material according to the entire period of use of the utilization Under target, based on the mass of the target prior to the first use. So of the utilization is for planar target at about 15 to 30% and for tube targets typically at 70 to 90%.

[0004] The in the interior of a tube targets Unrealised cooling of the target is much more effective than by the more favorable heat transfer in a tubular target in planar target, what enables higher superficial coating rates and thus higher energy densities. Nor has the inclination to local arcing during reactive sputtering reduced (referred to also as is [...] ) in particular. Using tube targets is then especially advantageous, when large area substrates are coated. During the insert rotates the Tube target slowly, while usually the magnetic field is stationary.

[0005] EP 1,225,249 B1 discloses a tubular target for cathode sputtering systems. At the ends of a tubular target body is disposed in each case a carrier tube or a connection pipe. Average of the support tubes, the project out from the target body, the target is incorporated in an installation. In one implementation a carrier tube is inserted into an open end of the target body and then secured by means of a screw, by a flange of the carrier tube is screwed in a front edge of the target body. Alternatively, a union nut provided at the target body is an external thread for, by means of which a flange of the mounting tube to the front end of the target body can be pressed.

[0006] DE 10 2004,058,316 A1 discloses a tubular sputtering target with a target body and arranged on at least one end of a pipe with a fastening device and/or cohesively tubing final cover wherein the fastening device or positively to the target body are connected.

[0007] The W0201440100 A1 discloses a target for a target body of a sputtering material is with a tubular Cathode sputtering system, and two at the target body which can be fastened to fittings for connecting the target body to a Cathode sputtering system, wherein a first fitting and a second fitting with a first end of the target body is connectable to a second end of the target body, and wherein at least one locking means is formed at each fitting, so as to connect the respective fitting non-rotatably, to the target body.

[0008] It is known as a monolithic target can be made that tube targets. Monolithic target usually no continuous support tube to point. Monolithic Austrian

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material yield of up to 80% and is significantly fewer targets allow a temperature sensitive, whereby particularly high power densities of up to 30 kW/m in sputtering are possible. This high deposition rates are possible and a higher throughput, whereby the properties of the deposited layers can be improved. A higher electrical conductivity on the generated layers each have, inter alia, for example.

[0009] The monolithic tube targets, especially in the case of the metal targets advantageous execution of, if the used sputtering material is a sufficiently large mechanical strength, ductility and fracture toughness has. The mechanical characteristics are especially critical for the use of monolithic target and the geometric interpretation of the end portion, since here partially (preferably less than 4 mm) need to be accomplished very thin wall thicknesses. This takes place usually by mechanical processing of the target body. (E) a monolithic tube targets Any damage one or the end portion can not inserted and the entire target must be re-made in the worst case.

[0010] (e) mechanical machining of the/An Alternative to the end region of the target body are disclosed, for example, in EP 1,225,249 B1 as terminals which.

[0011] Alternatively to monolithic target further known are bonded target. Here means of solder or the target body is. Bonding on a carrier tube applied, wherein a low-melting solder is used usually. This such high power densities are temperature sensitive and it may come upon deployment, targets and thus the development of higher temperatures (partial) melting of the to a (usually low melting [...] -) solder and a detachment of the target body from the support tube.

[0012] During the sputtering operation rotates about its longitudinal axis usually a tube target. Typical lie between 5 and 10 revolutions per minute speed. Usually a few weeks to months of such a target is the period of use, so that several 10,000 to 100,000 revolutions can take place.

[0013] Total it therefore comes at a cyclic thermomechanical stress, in particular at the connecting points between the individual components of a tube targets must be taken into account. Also what is important is that close tolerances for the rotational run-out can be observed in the individual components of a tube targets are, otherwise there will be an increased mechanical stress in said connecting zone.

[0014] (e) a tubular sputtering target can end region The reservoir or directly with further equipment items are in contact or be connected the Cathode sputtering system. For example, with a so-called end-block, or transmitted on both sides of the target with a respective end block, the electric power or the rotation and on the target.

[0015] On the use of materials for the components of a tube targets, where the respective linear thermal expansion differences, it can come under certain circumstances in the use of bonded tube targets or monolithic tube targets with attached fittings to mechanical stresses or deformations, the tube targets can lead to a loss of the mechanical stability or vacuum-tightness of the.

[0016] Through the rotation of the target and the cyclic thermal load it comes at different mechanical loads of the target on the target surface that can be used especially in monolithic target with attached fittings in the joining of the individual components of the tube targets can be effective. A loss of the failure by the mass or positive connection of the target body vacuum-tightness with the connection pieces the further sequence can be.

[0017] when brittle materials for the components of a tube targets are used in particular, the connecting locations are especially vulnerable to cracking and to subsequently to a failure of the entire target, for example by cooling water withdrawal.

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[0018] So it is up to the invention, an improved tubular target with prolonged useful life as well as provide a lesser slope to the formation of cracks or to the fracture of the target.

[0019] This problem is solved with the features of claim 1. Advantageous configurations are the object of the subclaims.

[0020] a tube target for cathode sputtering plants according to claim 1 is provided, e.g. for [...]. The Tube target comprises a tubular target body and at least one of a sputtering material is connected with the target body, projecting out from the target body, to a target body (flange) for connecting the fitting on Cathode sputtering system.

[0021] a first fitting having a first end of the target body and are, for example, a second fitting connected to a second end of the target body. The frontal areas of the target body are regarded as end. The ends of the target differ in nature may, for example, geometrically, wherein at least one end of the target is formed as hereinafter described. Alternatively, the two ends can be constructed symmetrically of the target, so that the connector (and the further elements described below) at a first end of the target said fitting at the opposite second end of the target (and the further elements) correspond to.

[0022] The target body is a vacuum-tight manner and non-rotatably connected with said at least one connector on at least one damper element and further comprising, between said at least one fitting and said target body is disposed.

[0023] a vacuum-tight manner and non-rotatably connected to each other are therefore connector and target body. Preferably, this compound is not releasably and/or integrally realized, for example by means of soldering, gluing, welding or a combination of the preceding methods and other methods such as screws not via the material, e.g. by means of screws and adhesive bonding. In particular, a seal or a sealing material between and joining piece target body additionally, such as an O-ring, be arranged, to provide a vacuum-tight connection in simple-wise.

[0024] Preferably, the at least one fitting securely with the target body connected, e.g. by means of soldering, gluing or a combination of screwing with gluing or soldering. Particularly preferably the at least one fitting is connected by means of adhesive bonding with the target body.

[0025] agent of the connecting piece or the connecting pieces can or said tubular target. Both vertically and horizontally are incorporated in a Tube target Cathode sputtering system. It it is from the performance of the function Cathode sputtering system is installed in a vertical or horizontal position whether the Tube target and whether one or both of the fittings are fixed on a rig tube targets.

[0026] during the operational state of an electric power is applied to a tube target, may range up to a few hundred kilowatts the. The necessary electric voltages of up to a few hundred volts and the electrical current intensities of several amperes must have the at least one fitting on the target body are transmitted.

[0027] The compound should have a certain electrical conductivity therefore ideally from fitting and target body or a low electrical resistance. Furthermore, should have a sufficient mechanical strength and ductility the compound.

[0028] The according to the invention has at least one damper element, on target, the target body is arranged between said at least one fitting and said. So between the target body and the at least one damper element is Preferably, the at least one Austrian

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Fitting arranged, with in each case at least one surface of the target body and that it at least a surface of said at least one fitting is connected. So that the damping action of the damping element is optimally guaranteed, since the applied voltages rotation load in operation of the target on the target by the optimally and uniformly in the connection zone between the target body and joining piece can be distributed. The size of the area, in which the damper element is arranged and effective, the respective geometric speech must of the target body and the at least one fitting, as well as the process conditions, with which the target is used, will be adapted.

[0029] In a preferred embodiment is between the target body and the at least one damper element and/or between the at least one fitting and said at least one damper element disposed a solder or an adhesive. By the solder or the adhesive will be improved further and the cohesion and the action of the damping means is additionally optimized vacuum-tightness of the target. What a form-locking connection between the connection piece and the target body and the damper element or can by adhesives or solders damper element are combined at least partly with a material connection, so that the target can be used under normal conditions of use and still stable more reliable in service.

[0030] The for connecting the fittings under normal conditions of use and a high strength adhesives or solders used slight elongations on point. The adhesives and solders (target body) and the materials for the inserted atomization materials show with respect to the at least one fitting typically a much smaller plastic deformation capability. Opposition to cracking by mechanical and/or thermo-mechanical load is low.

[0031] Depending on the choice of the respectively used solders or adhesive is a wide range of mechanical, thermal and electrical properties and property combinations possible. Typical solders can lie perfectly 50 MPa at greater the tensile strength So. Equally elongations to 20% are possible to. Basic data of various solders can be found for example in " J. [...] : "deployment and soldering techniques for mounting semiconductor solid-state lasers", thesis [...] Aachen, October 2011"

[0032] Even with adhesives characteristic pallet lies before a large. Typical epoxy resins that have been achieved, but in comparison with solders tend to pull or lower. tension and shear resistances and smaller elongations on.

[0033] So that the adhesion of the solder or the adhesive is optimal guaranteed, a pretreatment in direct contact with the solder or the adhesive can surfaces of the target body, of the connector or of said damping means is be provided. Such a pretreatment can take place for example on beams with sand, metal balls, or similar to a modified surface with certain roughness or an optimized radiation media and lead voltage condition. Furthermore, it may be necessary to provide the corresponding surfaces cleaned and grease-free.

[0034] in the radial direction between the thickness of said at least one damping element is preferably 0.25 and 5 mm.

[0035] In thicknesses are less than 0.25 mm, it may be that the damping effect is given already no longer be optimal, since the stiffness of the damping means is already structurally is reduced. In thicknesses of 0.25 mm is a process-safe handling and positioning of the damping means is no longer less optimally guaranteed. Thicknesses of 5 mm in turn can lead to greater already that especially in embodiments which additionally include a solder or an adhesive, the positioning of the individual components (fitting, target body, damper element) is made more difficult. The axial position of the damping element with respect to the target body is preferably in the vicinity of the areas of the target body, the show the greatest material wear (removing material in the radial direction of the target body).

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A thickness of said damping means is of greater 5 mm can already lead to a diminished utilization of target and undermine the maximum period of use of the target, since in the range, in which the damper element is located, the usable material thickness of the target body is reduced.

[0036] the invention is (fully) from the target in a target body The or sputtering material is. Coating material made, i.e. it is provided a so-called monolithic target.

[0037] Preferably, the metallically atomization materials used. In a preferred embodiment is made of a material selected from the following group of target body of the target (molybdenum, molybdenum-base alloy, titanium, titanium base alloy, copper, copper alloy). Continue the target body preferably consists of molybdenum or a molybdenum alloy.

[0038] The of the same or a similar material can at least one fitting of a different metallic material as the target body or be made. Under similar to I mean that at least 80 at % of the elements from which target body or. (E) fitting are made, are the same (for example in the event of a alloy).

[0039] In Table 1 preferred combinations are for the combination target body-material and joining piece-material listed exemplary, wherein under base is to be understood that are contained in the material of the corresponding element 50 at % greater.

[0041] There can have an impact on the connection between fitting and target body is particularly disadvantageous, when the difference in coefficients of thermal expansion of the materials used is too large. That is especially then on, when said fitting is made from a different material than the target body. Room temperature, for example, the coefficient of linear thermal expansion (CTE is) of molybdenum 5.2.10 16,10^{6 m/} mK and^{6 m/} mK from stainless steel about. In it comes to large differences in the CTE to tensile stresses in the connection zone after cooling, can lead to a cracking or damage of the compound. Injury can occur both in the manufacture of a tube targets than Such also in use. This in turn can lead to a loss of vacuum-tightness or Sequential Play to a loss of mechanical integrity of the target.

[0042] The spatial shape of the at least one damping element is preferably one of the following forms:

-Tube

-Film

-Grid

Network

-Spring

-Wire

-Rods

(E)-ring

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Patent Office

[0043] the at least one damper element is made from a metallic material Prefers.

[0044] The at least one damper element preferably has a coefficient of thermal expansion on manner is adapted to the other components of the target. In Table 2 guidelines are exactly for CTE as well as thermal conductivity and electrical conductivity of materials suitable for target body (WLF is) and for damping elements listed.

[0046] Preferably, it is, if the coefficient of thermal expansion of the damping element lies between the coefficient of thermal expansion of the target body and the at least one fitting. Particularly preferred the thermal expansion of the individual components of the combinations are tubular targets according to the invention:

_AOE280A2AO> | CTE

_AOE280A2AO> | CTE

Fitting

Fitting

[...] - [...] < 10

CTE damper element | < 10

| CTE_{target body-}[...] < 10

[0047] it It is also preferred, when the thermal conductivity of the damping means is greater than or equal to 15 W/mK, even more preferably greater than or equal to 40 W/mK, more preferably is greater than or equal to 75 W/mK.

[0048] The electrical conductivity of said damping means is greater than or equal to 1 is preferably _AOE296A0AO>^{6 more preferably} greater than or equal to 5-10 10^{6 even more preferably} greater than or equal to "^1-m"^{1 7 Q MO.}

[0049] In one embodiment of the invention are axially arranged side by side connector and damper element. Such an arrangement has the advantage that a form-fitting connection is or simple to realize by means of a threaded connection between connector and damper element for materially joining only a small area needs to be treated, advantageously in terms of what is additionally vacuum-tightness. This arrangement has the advantage that no additional shear stresses occur during thermal stress between fitting and damper element, if a larger difference in CTE of fitting and damper element is present.

[0050] In an alternative embodiment of the invention is the at least one damper element in addition to at least one portion of said at least one connector arranged radially. Such an arrangement has the advantage can be reduced that in this embodiment and joining piece by the existing greater connecting surface between damper element, occurring shear stresses in the connection zone.

[0051] also a good centring barness is given to the damper element of the connecting piece. In this arrangement is also advantageous that bending stresses occurring not Austrian

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directly in the connection zone between the connector and damper element be effective, as this would be the case for example in an axial arrangement.

[0052] The at least one damper element can be connected for example with the fitting by means of a screw connection.

[0053] In a screw connection (see Figure 1) and damper element axially of the connector connected at the end face abutting ends of the connecting piece and of the damping element can for example be adapted to be screwed together or their end faces of which have corresponding inside/magnification in Figure 1 is shown as well as in the external thread on.

[0054] a screw connection of radially arranged fitting and damper element For (see Figures 2-1, 2-2, 3, 4-1 and 4-2) may also or corresponding male threads. Internal thread be provided. For example, the damper element can have an internal thread and the connecting piece a corresponding external thread. Alternatively, have an external thread and the connecting piece in a corresponding internal thread also the damper element.

[0055] Alternatively or also in addition to the screw connection with the fitting by means of a solder connection or the at least one damper element can be connected an adhesive bond.

[0056] On the basis of the Figures embodiments be closer explained of the invention. It show:

[0057] Fig. 1, a schematic representation of a side view according to a first embodiment in cut end of a tube targets, wherein fitting (6a) and damper element (4a) are arranged axially next to one another.

[0058] Fig. 2-1, a schematic representation of a side view according to a second embodiment in cut end of a tube targets, wherein a damper element (4b) adjacent to a portion of the fitting (6b) is arranged radially.

[0059] Fig. 2-2, a schematic representation of a side view of an additional embodiment in cut end of a tube targets, wherein a damper element adjacent to a portion of the fitting (4b ') (6b) is arranged radially. The axially inner end portion of said damping means is in this embodiment extends radially beyond (4b ') at least a partial area of the fitting (6b).

[0060] Fig. 3 a schematic representation of a side view of an additional embodiment in cut end of a tube targets, wherein a damper element (4c) adjacent to a portion of the fitting (6c) is arranged radially. The damper element has a cross-section as seen in the tangential direction on, the contains a plurality of circular cross-sections.

[0061] Fig. 4-1, a schematic representation of a side view of an additional embodiment in cut end of a tube targets, wherein a damper element (4d) adjacent to a portion of the fitting (6d) is arranged radially. In this case the damper element is at least in part on a radially inner face of the fitting (6d) and only the axially inner end region of the damping element is disposed between fitting (6d) and target body (2d) arranged.

[0062] Fig. 4-2, a schematic representation of a side view of an additional embodiment in cut end of a tube targets, wherein a damper element adjacent to a portion of the fitting (4d ') (6d) is arranged radially. In this case the damper element is at least in part on a radially inner face of the fitting (6d) arranged and Austrian

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only the axially inner end region of the damping element is between fitting (6d) and target body (2d) arranged. The axially inner end portion of said damping means is in this embodiment extends radially beyond (4d ') at least a partial area of the fitting (6d).

[0063] Fig. 1a Fig. 4-2 each show schematic representations of an end of a tube targets according to various embodiments (1a-d) in cut side view. The described tube targets are symmetrically constructed, for example, can be (1a-d), so that the described elements of the represented (not shown) at the opposite end of the tube targets (1a-d) the elements (1a-d) correspond to end of the tube targets. Alternatively, the ends can comprise the described tube targets differently configured ends.

[0064] For example, a first end of the target be constructed in one of Figures represented as (1a-d) and a second end of the target shape such as a lid (1a-d) a differing therefrom. Continue alternatively a first end 1a (1a-d) according to one of the methods mentioned in Fig. can a tubular sputtering target Fig. 4-2 and a second end of said tube targets designs represented be constructed in accordance with a different 1a Fig in Fig. (1a-d). 4-2 shown embodiment be constructed.

[0065] Preferably, the two ends of the tube targets a symmetrical structure.

[0066] Alternatively is preferably an end shown in any one of Fig. 1 to 4-and the other end provided with a lid 2 represented formed.

[0067] particularly pronounced is the effect of said damping means is in one of the embodiments in FIG. 2-1, FIG. 2-2 or 3 are shown Fig..

[0068] first of all elements and characteristics described are described below, the various embodiments of the in the 1a Fig Fig.. 4-2 (1a-d) together have shown tube targets.

[0069] The [...] (1a-d) can be used in sputtering device such as tube targets. With the tube targets according to the invention and thus reduced the useful life (1a-d) can be improved the break susceptibility a target.

[0070] rotation load to the formation of cracks in the material of the targets it may by the of the target body, the fitting or optionally also of the adhesive or solder come present, and the target must be exchanged in consequence of it at an early stage. Means of the schematically represented (1a-d) this cracking may be reduced tube targets, so that the service life can be substantially increased.

[0071] The (1a-d) are so-called monolithic target represented target, i.e. the target body are completely from the sputtering material is made (2a-d). (Continuous) carrier tube does not pose a This, above all on, on which the sputtering material is e.g. is soldered ("bonded target").

[0072] Each of the displayed target (6a-d) responds to the transduced (1a-d) has at least a connector for connecting to a target body of the target body (2a-d) protrudes and serves Cathode sputtering system. With this fitting of the target body is connected in a vacuum-tight manner. For example, a vacuum-tight manner by means of gluing or soldering and joining piece (6a-d) are connected (2a-d) target body, further can optionally one or more sealing rings or. O-rings be arranged between the two elements.

[0073] Preferably, the inner diameter corresponds to the internal diameter of said at least one fitting (2a-c) of the target body (6a-c), so that a planar or stepless transition is provided between the two elements. In the case of the embodiment 4-1 is represented in Figure, the inner diameter corresponds to the fitting (6d) in the region of the damping element (4d) not the inner diameter of the target body (2d), the radial extent of said damping means is (4d), however is adapted in such a manner that the internal diameter of said damping means is (4d) that of the target body (2d) corresponds to.

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[0074] Each of the displayed target (1a-d) at least one damper element (4a-d ') does, therefore, further on. This damper element is disposed between the target body (2a-d) and said fitting (6a-d).

[0075] Advantageously, 4-2 are represented in the embodiments is in the at least one damper element 1a Fig. Fig. (4a-d ') so (2a-d) and said at least one connector disposed between the target body (6a-d), with in each case at least one surface of the target body that it (2a-d) and at least one surface of said at least one fitting is connected (6a-d). 4-1 and 4-2 are represented in Figure in the case of embodiments, the damper element is at least in part on a radially inner surface of said fitting (6d) arranged and only the axially inner end region of the damping element (4d and 4d ') is between fitting (6d) and target body (2d) arranged. As in Fig. 4-2 shown is the axially inner end region of the damping element can extend radially beyond at least a portion of said fitting (4d ') (6d).

[0076] target body and joining piece (6a-d) can be attached to each other by (2a-d). Between the target body (2a-d) and the damper element (4a-d ') and/or between the connection piece (4a-d') (6a-d) and the damper element can be arranged additionally a solder or an adhesive.

[0077] are described below with respect to the various configurations of the tube targets in Figures shown the individual elements (1a-d) (and their differences) described in more detail.

[0078] 1 shows a first embodiment of a tube targets Fig. (1a), comprising a reduced break susceptibility. As shown schematically, the Tube target points (1a) a connector (6a) on, the projects partially from the target body (2a). Furthermore, the Tube target (1a) a damper element (4a) on, which in the shown embodiment is arranged axially adjacent to the fitting, and on the side facing away from the imaged end of the tube targets of the connecting piece.

[0079] The connection between fitting (6a) and damper element (4a) can be realized in this case, for example, by welding or friction welding.

[0080] Fig. 2-1 shows a second embodiment a tubular sputtering target (1b). Unless otherwise noted, with respect to the above-described elements and characteristics of the tube targets can 1 Fig. (1a) and for the in Fig. 2-1 represented Tube target (1 b) are used.

[0081] Unlike the first embodiment according to Fig. 1, Fig. shows 2-1 a tube target (1b) with a target body (2b) and at least one connector (6b), and a damper element (4b), which between fitting (6b) and target body (2b) in the radial direction that is, looking radially outward from the axis A according, adjacent the at least one connector (6b) is arranged. The damper element (4b) is so carried out also in this embodiment that it is provided with a respective surface of the connecting piece (6b) (in this case an outer surface) and a surface of the target body (2b) is connected (in this case an inner surface).

[0082] Fig. 2-2 is different from FIG. 2-1 thereby that the axially inner end portion of said damping means is in this embodiment radially over at least a partial area (4b ') of the connecting piece (6b) extends.

[0083] 3 shows a third embodiment of a tube targets Fig. (1c). Unless otherwise noted, with respect to the abovementioned can Fig. 1.2-1 and 2-2 for the described elements and characteristics of the tube targets 3 represented in Fig. (1a-b) also Tube target (1c) are used.

[0084] The spatial arrangement of the embodiment shown in 3 corresponds to that of the 2-1 shown in Fig. Fig. tube targets (1b). Unlike the with respect to FIG. 2-1 described Tube target (1b), the Tube target points (1c), however, a damper element (4c) on, which has seen a cross-section in the tangential direction, the contains a plurality of circular cross-sections.

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[0085] Such a cross-section can be achieved, for example that the damper element (4c) the spatial has the form of a spring, and is constructed from one or more annular elements with a circular cross-section also.

[0086] (not shown in Figures) Alternatively, an inventive damper element can also have a differently formed cross-section as seen in the tangential direction, such as one or more oval cross-sections or also one or more square or rectangular cross-sections containing cross-section.

[0087] Figure 4 shows a tube target (1d) with target body (2d) and joining piece (6d), which has also a damper element (4d). Unlike the in Figures 1 to 3 represented embodiments of the invention, the damper element (4d is) at least partially bonded to an inner surface of said fitting (6d) arranged in the inner end region of the damping element and is only (4d) between fitting (6d) and target body (2d) arranged. The effect of said damping means is in this case only targeted absorbing element present in the inner end portion of the is.

[0088] Fig. 4-2 is different from FIG. 4-1 thereby that the axially inner end region of the damping element (4d ') in this embodiment radially over at least a partial area of the fitting (6d) extends.

[0089] In preferred embodiments of the invention is the at least one damper element (6b-c) disposed on an outer surface of said at least one fitting (4b-c).

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1a -4a -6a 2a-d T d Tube target [...] -d fitting A axis Tube target d' damper element

Fig. 2-1