WO2024089576A1

WO2024089576A1 - Sputter ion pump

Info

Publication number: WO2024089576A1
Application number: PCT/IB2023/060671
Authority: WO
Inventors: Derek Alexander CLEMENT
Original assignee: Edwards Vacuum Llc
Priority date: 2022-10-27
Filing date: 2023-10-23
Publication date: 2024-05-02

Abstract

Sputter ion pump comprising: an anode (14), wherein the anode comprises a radial symmetry and wherein the anode defines a plurality of hollow cylinders and is connected to a voltage supply, a cathode comprising a plurality of cathode elements (22, 22', 22") arranged directly next to the anode and connected to ground.

Description

SPUTTER ION PUMP The present invention relates to a sputter ion pump and in particular a compact high-performance sputter ion pump to be inserted into a vacuum apparatus. Conventional sputter ion pumps (SIP) comprise an anode provided by a hollow cylinder. At the respective ends of the hollow cylinder, cathodes as metal plates are arranged, wherein anode and cathode are kept at different electrical poten- tials. In particular, the cathode may be connected to the ground wherein the anode may be connected to a high voltage. Anode and cathode are positioned in a magnetic field provided to the axis of the hollow cylinder by magnets usually disposed outside the cathodes and outside the vacuum. By the voltage between the anode and the cathode, in addition to the magnetic field parallel to the axis of the anode, the paths of free electrons in the anode cells are augmented on spiral trajectories. The free electrons generate ions from the gas molecules in- side the vacuum, which are accelerated by the electric field between the anode and cathode. The accelerated ions will impact onto the cathode, wherein both the sputtered and remaining cathode material act as a getters removing the ions from the vacuum. In common SIPs, in order to enhance the pump performance of the SIP, one or more hollow cylinders as anodes are arranged within the same plane between the cathode plates. Since at least the anode and the cathode of the SIP need to be placed in the vacuum, the building space may be restricted if the SIP shall be placed as close as possible to or within the vacuum chamber to be evacuated. Thereby at the same time the number of hollow cylinders is restricted limiting the pump performance. It is known to reduce the required space by arranging parts of the SIP outside the vacuum such as the magnets. However, this may by disadvantageous since it decreases the magnetic field at the cathode and anode and requires larger magnets than would be necessary if they would be placed closer to the anode and cathode as well as specifically adapted housings of the SIP resulting in an SIP with an overall larger size and weight. Further- more, when the specifically adapted housing of the SIP is connected to a vacuum apparatus, the distance between the SIP and a vacuum chamber of the vacuum apparatus is increased further decreasing the pump performance. Thus, it is an object of the present invention to provide a sputter ion pump to be inserted into a vacuum apparatus having an improved pump performance. The object is solved by a sputter ion pump according to claim 1. The sputter ion pump (SIP) according to the present invention comprises an anode. The anode defines a plurality of hollow cylinders. Therein, the anode is connected to a voltage supply. Further, the SIP comprises a cathode comprising a plurality of cathode elements arranged directly next to the anode. The cathode elements may by connected to ground or kept at a lower potential than the anode. Therein, at least two cathode elements are made from different materi- als. Sputter ion pumps are typically of one of three types: Conventional (CV) sputter ion pumps also known as diode ion pumps, Differential (DI) sputter ion pumps also known as noble diode pump, and Triode (TR) sputter ion pumps. The distinction between these types is the pumping element, which consists of the anode, the cathode, and the electric potential of each. A CV element consists of an anode under high voltage (3-7 kV) and a grounded Titanium cathode plate on either side. A DI element is a CV element with one of the Titanium cathode plates replaced by a Tantalum cathode plate. A TR element switches the poten- tial of the anode and cathode from those in a CV element (anode is grounded, cathodes at high voltage), implements some kind of geometric alteration of the cathode plates (deviating from a simple, flat plate). CV pumps have the highest nominal pumping speed; however, it is well established that CV pumps cannot pump noble gasses stably for long durations. Once stability is lost, a CV pump will cyclically release large quantities of noble gasses from the cathode plates. DI pumps have ~80% the nominal pumping speed of a similarly sized CV pump; however, it is well established that a DI element will pump noble gasses more stably than a CV element. Thus, by the different materials of the at least two cathode elements, different types of SIPs can be integrally built in one setup, thereby increasing the versatility of the vacuum pump and the pump perfor- mance for different types of gases. Preferably, the anode comprises a radial symmetry. By the radial symmetry the number of anode cells, i.e. hollow cylinders, within the volume of the pump can be maximized. Thereby, a compact SIP can be built, which provides improved pump performance without increase of the required building space. Preferably, the SIP comprises one or more magnets and may comprise one or more pole pieces, wherein the magnets generate a magnetic field along the axis of the hollow cylinders of the anode. Preferably, the one or more magnets are in direct contact with the cathode ele- ments. Additionally or alternatively, the one or more magnets are in direct con- tact with the pole pieces. Thus, the magnets may be placed between the pole pieces and the cathode elements, in particular in direct contact with each of them. Preferably, the anode and the cathode are connected to a flange. Therein, more preferably the anode and the cathode are completely arranged within the area of the flange. Thus, a compact design is provided. In addition, the magnets and the pole pieces may be connected to the flange and preferably within the area of the flange. Preferably, the anode is directly connected to the flange. Therein, connection of the anode to the flange may be facilitated by supporting elements preferably made from an insulating material. No further intermediate elements are neces- sary. Thereby, structural stability is increased and at the same time a compact design is achieved. Preferably, the pole pieces are in direct contact to the flange. No intermediate elements are present to achieve a compact design. Preferably, the cathode elements are directly connected to the flange via the magnets pole pieces. Thus, the pole pieces carry the cathode elements. Preferably, the anode and the cathode extend axially from the flange. More preferably, also the magnets and the pole pieces extend axially from the flange. Preferably, the flange comprises a first surface and an opposite second surface, wherein the first surface is connected to the second surface by a side surface. The second surface is at least partially arranged in the vacuum, when the SIP is connected or mounted to a vacuum apparatus. The anode and the cathode are connected to the second surface of the flange and preferably extend axially from the second surface. Preferably, the flange is built as blank flange, i.e. has a disk shape. Preferably, the anode extends in an axial direction from the flange which coin- cides or essentially coincides with the normal direction of the second surface, i.e. the axial extension is perpendicular or substantially perpendicular to the second surface. Preferably, the axis of radial symmetry coincides or substantially coincides with the normal direction of the second surface, i.e. the axis of radial symmetry is perpendicular or substantially perpendicular to the second surface. Preferably, the anode and the cathode are connected to a housing of the SIP by the flange. Thus, the flange itself does not provide any housing of the SIP. Preferably, the SIP does not provide a housing. Instead, a housing of the SIP is provided by the vacuum chamber of the vacuum apparatus when the SIP is connected or mounted to the vacuum apparatus. Thus, by inserting the SIP into the vacuum apparatus and mounting the SIP via the flange, a vacuum tight housing of the SIP is provided by the vacuum apparatus itself. Preferably, the SIP is insertable or at least partially insertable into a vacuum apparatus. Thus, the SIP can be placed in close proximity or even within the vacuum apparatus minimizing the distance between the SIP and a vacuum chamber of a vacuum apparatus. Thereby, pump performance can be further increase. In particular, the SIP of the present invention has no housing or casing and the vacuum tight housing necessary for operation of the SIP is provided by a vacuum chamber or vacuum apparatus itself, when the SIP is inserted into the vacuum apparatus. Preferably, the anode and the cathode are arranged completely inside the vac- uum. Preferably, the magnets and/or the pole pieces are completely arranged inside the vacuum. If the SIP is connected to a flange, the complete SIP can be inserted into the vacuum by connecting the flange to a vacuum apparatus. Preferably, the anode comprises a plurality of anode elements connected at a centre element and preferably arranged in radial symmetry. Thus, the anode elements are arranged in an equal angle to each other. Therein, each anode element comprises one or more hollow cylinders. Thus, by the number of anode elements the number of anode cells, i. e. hollow cylinders, can be increased without increasing the overall dimensions of the SIP. Preferably, the centre element coincides with the axis of radial symmetry. Preferably, the extension of the centre element is along or substantially along the normal direction of the second surface of the flange, i.e. perpendicular or substantially perpendicular to the second surface. Preferably, the anode elements extend radially from the centre element. Preferably, all anode elements are built identically. Alternatively, at least two of the anode elements are built differently. This relates in particular to one or more of the size of the anode cells, the arrangement of the anode cells and the num- ber of anode cells in each of the anode elements. Preferably, the anode cells extend in a direction perpendicular or substantially perpendicular to the axial extension of the anode. Since the anode cells are built as hollow cylinders, their centre axis corresponds to the direction of extension. Preferably, the anode cells, i.e. their centre axes, extend in a direction perpen- dicular or substantially perpendicular to the axis of radial symmetry. Preferably, the anode cells, i.e. their centre axes, extend in a direction parallel or substantially parallel to the flange, in particular to the second surface of the flange. Preferably, the anode comprises three anode elements arranged in 120° relative to each other. Alternatively, the anode comprises four anode elements arranged in 90° relative to each other. In the case that the anode comprises three anode elements, each anode element may comprise 6 anode cells/hollow cylinders re- sulting in 18 anode cells of the SIP in a very compact space. In particular, the radial symmetric arrangement of the anode elements can be fit to the size of the flange thereby further reducing the space requirements of the SIP. Preferably, the number of cathode elements is equal to the number of anode elements. Thus, in the case that the anode comprises three anode elements also three cathode elements are present in the SIP. Preferably, each cathode element is integrally built or, in other words, a single piece. Further, due to integrally building the respective cathode elements, the number of necessary elements is reduced thereby simplifying the assembly. Preferably, each cathode element overlaps with two anode elements. Thus, one cathode element builds the cathode of a first anode element and a second anode element, directly adjacent to the first anode element. Thus, the number of parts of the cathode and their fixturing components can be reduced, reducing the complexity of the SIP and the required building space. Preferably, the cathode elements are built as angled plates. In particular, if the anode elements are arranged with an angle of 120° relative to each other, the cathode elements are built as angled plates with an angle of 120°. Similarly, if the anode elements are arranged with an angle of 90° relative to each other, the cathode elements also have an angle of 90° relative to each other. In particular, all cathode elements have the same shape. Due to the radial sym- metry of the anode, the cathode elements may have the same shape conforming with the shape of the anode. Preferably, each cathode element is made from a single material. Thus, manu- facturing the cathode elements is facilitated since no welding, brazing or the like is necessary in order to create the cathode elements in particular if different materials are intended to be implemented in the SIP. Preferably, at least one cathode element is entirely built from titanium and at least one cathode element is entirely built from tantalum. In particular, by the titanium cathode a CV pump is created, wherein by the tantalum cathode a DI pump is created. Preferably, at least two opposite cathode elements (i.e. on opposite sides rela- tive to the respective anode element) and the respective anode acting as con- ventional (CV) SIP and at least two opposite cathode elements and the respec- tive anode acting as differential (DI) SIP. More preferably, the ratio between the CV pumping and the DI pumping is 50:50 or 33:67, or between 50:50 and 33:67. In particular, if two cathode elements are built from titanium and one cathode element is built from tantalum, a ratio between CV pumping and DI pumping of 1:3 is established. Preferably, the anode is built as one piece. Thereby, manufacturing of the anode is facilitated, and the anode can be manufactured with higher precision and smaller tolerance so that the SIP can be fit into the reduced building space. Preferably, the anode is connectable to a voltage supply by a feedthrough con- nector feeding the voltage of the voltage supply through the flange preferably into the vacuum. Therein, the feedthrough connector is directly connected to the anode. Thus, the feedthrough connector comprises element a conductor ex- tending from a side outside the vacuum, through the flange or wall of the vac- uum apparatus directly to the anode. In particular, the conductor element is built as one piece. In particular, the feedthrough connector is connected to the centre of the anode. Due to the direct connection of the anode additional parts like connectors in the vacuum can be avoided thereby simplifying the construc- tion of the SIP. Preferably, the anode comprises a plurality of supporting elements to fix the anode in a mounting position. The supporting elements are made from an elec- trical insulating material, preferably a ceramic material. By the supporting elements the anode can be electrically isolated from the flange or other parts of the vacuum pump in order to avoid shorts or arcing. In the following the present invention is described in more detail with reference to the accompanying drawings. The figures show: Figure 1 a perspective view of the sputter ion pump according to the present invention, Figure 2 a detailed view of the anode, Figure 3 a sectional view of the anode in a mounted state, Figure 4 a top view of the sputter ion pump of figure 1 and Figure 5 a detailed view of all the magnets of figure 1. Referring to Figure 1 showing a sputter ion pump (SIP) according to the present invention. The SIP 10 is mounted on a flange 12 and all parts of the SIP 10 (including but not limited to the anode 14, the cathode elements 22 and the magnets 24, all described in more detail below) can be inserted into the vacuum by connecting the flange 12 to a vacuum chamber or vacuum apparatus. Therein, the SIP 10 comprises a radial symmetry in order to fit into the area of the flange 12. By the radial symmetry the space provided by the flange 12 is efficiently used, thereby enhancing the pump performance of the SIP 10 without increasing the required building space. The SIP 10 comprises an anode 14 shown in detail in Figure 2. The anode 14 in the example of the figures comprises three anode elements 16, which are arranged with a radial symmetry and an angle of 120° relative to each other. Thereby a radial symmetry is established relative to a symmetry axis 20. Other configurations are possible as well. For example, the anode 14 may have four anode elements which are arranged with an angle of 90° relative to each other. Therein, the anode elements 16 are connected to a centre element 18, wherein the symmetry axis 20 runs through the centre element 18 and the anode ele- ments 16 extend radially from the centre element 18. Therein, in the example of the present figures, each anode element 16 comprises six hollow cylinders 22 arranged in a 2D array. Other configuration and in particular other numbers of hollow cylinders are possible. Therein, the hollow cylinders have a diameter be- tween 10 – 30 mm and preferably between 15 – 20 mm. In order to increase the precision of the anode 14, the anode 14 is built from a single piece facilitat- ing assembly of the anode 14. Referring to Figure 3, the anode 14 is connected to a voltage supply (not shown) outside the vacuum via an electrical feedthrough 40. Therein, the flange 12 comprises an opening 48. A conductor 42 extends through the opening and is surrounded by an insulating material 44, preferably built from a ceramic mate- rial. Therein, the insulating material 44 and the conductor 42 passes through the flange 12 in a vacuum tight manner. The conductor 42 is directly connected to the anode 14 and preferably at the centre element 18 of the anode 14. Hence, no additional conductors within the vacuum are required connecting the anode to the voltage supply, since the conductor 42 extends from the outside of the vacuum into the vacuum and is directly connected to the anode 14. Further, referring to Figure 3, the anode 14 is supported by supporting elements 30 comprising pegs 36 which are attached on the bottom surface of the anode 14. Similar, corresponding pegs 38 are attached to the flange 12 or a base element 29. The pegs 36 of the anode 14 may be integrally built with the anode 14. Similar, the pegs 38 of the flange 12 may be integrally built with the flange 12 or the base element 29. Further, each supporting element 30 comprises a ceramic element 34, wherein the peg 36 of the anode 14 and the peg 38 of the flange 12 are received by the ceramic element 34. The ceramic element may have a sleeved shape with an opening, wherein the opening is configured to receive the pegs 36,38. Therein, the opening of the ceramic element 34 is big enough to receive the pegs 36, 38. By the ceramic element the peg 36 of the anode 14 is kept in a distance from the peg 38 of the flange 12 to avoid shorts or sparks. Alternatively, instead of pegs 38 connected to the flange 12 or the base element 29, the flange 12 or the base element 29 may comprise recessions or troughs which receive the ceramic element 34. Therein, the number of sup- porting elements may correspond to the number of anode elements 16. Thus, each anode element is structurally connected to the flange by the supporting elements 30. Preferably, similar supporting elements may be arranged on the upper side of the anode (not shown), wherein the supporting elements on the uppers side of the anode 14 are received by a cap element 28. The cap element 28 may also support a NEG pump module connected to the SIP 10 in a stacking manner in order to create a combined NEG-SIP pump module, wherein the NEG as well as the SIP are within the area of the flange 12. Thus, NEG and SIP can together be inserted into a vacuum chamber. Further, the supporting elements 30 are surrounded by sputter shields 32 pref- erably welded to the anode 14 and preventing elements from the cathode being sputtered onto the ceramic elements 34 and creating a conductive path from the anode to ground of the flange 12. Referring back to Figure 1. The anode 14 is surrounded by cathodes, wherein the cathodes are built from respective cathode plates 22, 22', 22''. The cathodes may have a thickness between 0.5 mm and 2 mm and more preferably between 1 mm and 1.2 mm. In particular, the thickness may be between 0.5 mm and 2 mm for a titanium cathode and between 0.5 mm and 1 mm for a tantalum cathode. If the anode 14 has three anode elements arranged with an angle of 120° relative to each other, the cathode plates 22, 22’, 22’’ are also angled by 120°. Therein, a first part of each cathode plate 22, 22’, 22’’ is arranged directly next to a first anode element 16, wherein the second part of the cathode plate 22, 22’, 22’’ is arranged directly next to a subsequent anode element 16. Thereby, each cathode plate 22, 22’, 22’’ overlaps with two different anode el- ements 16 thereby reducing the number of necessary parts for the SIP and facilitating assembly thereof. Preferably, the first cathode plate 22 and the second cathode plate 22' are built as titanium cathodes, wherein a third cathode plate 22'' is built as tantalum cathode plate. By the different materials, different types of sputter ion pumping is enabled. Thus, by the tantalum cathode plate 22’’ DI pumping is enabled with two anode elements, wherein by the titanium cathode plates 22, 22’ conven- tional pumping (CV) is enabled. Thereby, each cathode plate 22, 22', 22'' is entirely built only from one material. Thus, welding or brazing together plates from different materials is not necessary, thereby simplifying the structure of the present SIP. The cathode plates 22, 22’, 22’’ are connected to the flange via a base element 29 as shown in Figure 3. Therein, the cathode plates 22, 22’, 22’’ may be held in place within the pump assembly by the base element 29, the pole pieces 26, and cap element 28. Therein, the cathode plates 22, 22', 22'' may be clamped between the pole pieces 26 and the base element 26, preferably together with the magnets 24. Directly connected to the cathode plates 22, 22’, 22’’ magnets 24 are arranged and connected to a surface of the cathode plates 22, 22’, 22’’ opposite to the anode 14. Therein, preferably two magnets are in direct contact with one cath- ode plate 22, 22’, 22’’ arranged with an angle of 120° relative to each other. Thus, on both sides of each anode element 16 one magnet 24 is arranged in order to create a magnetic field in an axial direction of hollow cylinders of the anode 14. Preferably, the magnets are samarium cobalt magnets but can be also built as neodymium magnets or the like. In the example of the Figures, the SIP comprises six magnets 24. By the indi- vidual magnets a magnetic circuit is created. Rather than closing a magnetic loop from the magnet on one side of the anode to the magnet on the other side of the anode preferably by a yoke as in the prior art, the magnetic circuit created for the SIP according to the present invention forms a combined closed loop around all anode elements. The magnetic field goes across the respective gaps and the respective tips of the anode elements 16 opposite to the centre element 18 of the anode 12 to the magnet on the other side. It is then directed to the magnet of the adjacent anode element. The loop is closed after the field crosses the other two gaps and is redirected to the starting position. The magnetic circuit is indicated by arrows 54 in Figure 4. Hence, the magnetic circuit is circular in a plane perpendicular to the axial direction of the SIP or in a plane parallel to the surface of the flange 12. By this specific design of the magnetic circuit a radial symmetric arrangement of the SIP is provided leading to a compact and an efficient SIP. Referring back to Figure 1, the magnets 24 are surrounded by pole pieces 26 which are also bend by an angle of 120 degree, i. e. having the same angle as the anode elements 16 relative to each other. The pole pieces 26 have a thick- ness of between 3 mm and 10 mm and preferably between 4 mm and 8 mm and are made of a soft steel plate or sheet, holding the magnets in place and guiding the magnetic flux. The pole pieces 26 are fixed to the base element 29 and in direct contact with the flange 12. As shown in Figure 5 the pole pieces 26 comprise a recess 52 in order to receive the magnets 24 with high precision and small tolerances. Thus, the magnets 24 are kept in place by the respective recess 52 without the need of additional fixtures. Similar to the base element 29, the pole pieces are fixed to a cap element 28, fixing the cathode plates 22 in an axial direction. As shown in Figure 5, also the cap element 28 comprises a recess 53 receiving the cathode plates 22 and the magnets 24. Therein, the cap element 28 may be configured to mount an NEG module on top of the SIP in order to create a combined NEG-SIP pump module, wherein the NEG as well as the SIP are within the area of the flange 12. Thus, NEG and SIP can together be inserted into a vacuum chamber. Hence, by the present invention a compact design of a high performance SIP is provided exploiting a new design by implementing the radial symmetry of the anode and the additional elements. Thereby, the cathode, the magnets, the pole pieces and also the magnetic circuit are adapted to provide a high pump perfor- mance. Further aspect of the present invention: Aspect 1: Sputter ion pump comprising: an anode, wherein the anode defines a plurality of hollow cylinders and is connected to a voltage supply, a cathode comprising a plurality of cathode elements arranged directly next to the anode and connected to ground, wherein the anode comprises a radial symmetry. Aspect 2: Sputter ion pump according to aspect 1, wherein the anode and the cathode are connected to a flange. Aspect 3: Sputter ion pump according to aspect 2, wherein the anode and the cathode are completely arranged within the area of the flange. Aspect 4: Sputter ion pump according to aspects 2 or 3, wherein the anode and the cathode extend axially from the flange. Aspect 5: Sputter ion pump according to any of aspects 1 to 4, wherein the anode and the cathode are arranged completely inside the vacuum. Aspect 6: Sputter ion pump according to any of aspects 1 to 5, wherein the anode comprises a plurality of anode elements connected at a center and ar- ranged in a radial symmetry, wherein each anode element comprises one or more hollow cylinders. Aspect 7: Sputter ion pump according to aspect 6, wherein the anode comprises three anode elements arranged in 120° relative to each other. Aspect 8: Sputter ion pump according to aspects 6 or 7, wherein the number of cathode elements is equal to the number of anode elements. Aspect 9: Sputter ion pump according to any of aspects 6 to 8, wherein each cathode element overlaps with two anode elements. Aspect 10: Sputter ion pump according to any of aspects 1 to 9, wherein the cathode elements are built as angled plates preferably with an angle of 120°. Aspect 11: Sputter ion pump according to any of aspects 1 to 10, wherein at least two cathode elements are made from a different material. Aspect 12: Sputter ion pump according to any of aspects 1 to 11, wherein each cathode element is made from a single material. Aspect 13: Sputter ion pump according to any of aspects 1 to 12, wherein at least one cathode element is entirely built from Titanium and/or wherein at least one cathode element is entirely built from Tantalum. Aspect 14: Sputter ion pump according to any of aspects 1 to 13, wherein at least one cathode element and the anode acting as conventional, CV, sputter ion pump and at least one cathode element and the anode acting as differential, DI, sputter ion pump. Aspect 15: Sputter ion pump according to any of aspects 1 to 14, wherein the ratio between CV pumping and DI pumping is between 50:50 and 33:67. Aspect 16: Sputter ion pump according to any of aspects 1 to 15, wherein the anode is built as one piece. Aspect 17: Sputter ion pump according to any of aspects 1 to 16, wherein the anode is connected to the voltage supply by a feedthrough connector, wherein the feedthrough connector is directly connected to the anode. Aspect 18: Sputter ion pump according to any of aspects 1 to 17, wherein the anode comprises a plurality of supporting elements to fix the anode in a mount- ing position, wherein the supporting elements are made from an electrical insu- lation material, preferably a ceramic material. Aspect 19: Sputter ion pump comprising: an anode, wherein the anode defines a plurality of hollow cylinders and is connected to a voltage supply, a cathode comprising a plurality of cathode elements arranged directly next to the anode and connected to ground, and magnets in direct contact with the cathode ele- ments wherein by the magnets a magnetic circuit is generated perpendicular to the direction of extension of the anode. Aspect 20: Sputter ion pump according to aspect 19, wherein the anode and the cathode are connected to a flange. Aspect 21: Sputter ion pump according to aspect 20, wherein the anode, the cathode and the magnets are completely arranged within the area of the flange. Aspect 22: Sputter ion pump according to aspects 20 or 21, wherein the anode, the cathode and the magnets extend axially from the flange. Aspect 23: Sputter ion pump according to any of aspects 20 to 22, wherein the magnetic circuit is parallel to the flange. Aspect 24: Sputter ion pump according to any of aspects 19 to 23, wherein the anode, the cathode and the magnets are arranged completely inside the vac- uum. Aspect 25: Sputter ion pump according to any of aspects 19 to 24, wherein the magnetization direction of each magnet is perpendicular to the direction of radial extension of the anode and preferably in a plane parallel to the flange. Aspect 26: Sputter ion pump according to any of aspects 19 to 25, wherein the magnets are in direct contact with the cathode elements. Aspect 27: Sputter ion pump according to any of aspects 19 to 26, wherein each cathode element is in direct contact with two magnets arranged in an angle to each other. Aspect 28: Sputter ion pump according to any of aspects 19 to 27, wherein the magnets are built as straight plates. Aspect 29: Sputter ion pump according to any of aspects 19 to 28, wherein the anode comprises a plurality of anode elements connected at a center and arranged in a radial symmetry, wherein each anode element comprises one or more hollow cylinders. Aspect 30: Sputter ion pump according to aspect 29, wherein the anode com- prises three anode elements arranged in 120° relative to each other. Aspect 31: Sputter ion pump according to aspects 29 or 30, wherein the mag- nets are surrounded by pole pieces and the number of pole pieces is equal to the number of cathode elements. Aspect 32: Sputter ion pump according to any of aspects 19 to 31, wherein the magnetic circuit encircles the complete anode and preferably all anode ele- ments. Aspect 33: Sputter ion pump according to any of aspects 19 to 32, wherein the magnets are surrounded by pole pieces. Aspect 34: Sputter ion pump according to aspect 33, wherein the pole pieces are built as angled plates preferably with an angle of 120°. Aspect 35: Sputter ion pump according to any of aspects 33 or 34, wherein each pole piece comprises a recess to receive at least partially one or more of the magnets.

Reference signs SIP flange anode anode element centre element symmetry axis hollow cylinder , 22', 22'' cathode plates magnet pole piece cap element base element support element sputter shield ceramic element pegs pegs electrical feedthrough conductor insulation element opening recess recess 54 magnetic circuit

Claims

CLAIMS 1. Sputter ion pump comprising: an anode, wherein the anode defines a plurality of hollow cylinders and is connected to a voltage supply, a cathode comprising a plurality of cathode elements arranged directly next to the anode and connected to ground, wherein at least two cathode elements are made from a different material. 2. Sputter ion pump according to claim 1, wherein the SIP is insertable into a vacuum apparatus. 3. Sputter ion pump according to claim 1 or 2, wherein the anode comprises a radial symmetry. 4. Sputter ion pump according to any of claims 1 to 3, wherein the anode and the cathode are connected to a flange. 5. Sputter ion pump according to claim 4, wherein the anode and the cathode are completely arranged within the area of the flange. 6. Sputter ion pump according to claims 4 or 5, wherein the anode and the cathode extend axially from the flange. 7. Sputter ion pump according to any of claims 1 to 6, further comprising one or more magnets, wherein the magnets are arranged completely inside the vacuum. 8. Sputter ion pump according to any of claims 1 to 7, wherein the anode comprises a plurality of anode elements connected at a centre element and preferably arranged in a radial symmetry, wherein each anode element comprises one or more hollow cylinders. 9. Sputter ion pump according to claim 8, wherein the anode comprises three anode elements arranged in 120° relative to each other. 10. Sputter ion pump according to claims 8 or 9, wherein the number of cath- ode elements is equal to the number of anode elements. 11. Sputter ion pump according to any of claims 8 to 10, wherein each cathode element overlaps with two anode elements. 12. Sputter ion pump according to any of claims 1 to 11, wherein the cathode elements are built as angled plates preferably with an angle of 120°. 13. Sputter ion pump according to any of claims 1 to 12, wherein each cathode element is made from a single material. 14. Sputter ion pump according to any of claims 1 to 13, wherein at least one cathode element is entirely built from Titanium and/or wherein at least one cathode element is entirely built from Tantalum. 15. Sputter ion pump according to any of claims 1 to 14, wherein at least one cathode element and the anode acting as conventional, CV, sputter ion pump and at least one cathode element and the anode acting as differen- tial, DI, sputter ion pump. 16. Sputter ion pump according to any of claims 1 to 15, wherein the ratio between CV pumping and DI pumping is between 50:50 and 33:67. 17. Sputter ion pump according to any of claims 1 to 16, wherein the anode is built as one piece. 18. Sputter ion pump according to any of claims 1 to 17, wherein the anode is connected to the voltage supply by a feedthrough connector, wherein the feedthrough connector is directly connected to the anode. 19. Sputter ion pump according to any of claims 1 to 18, wherein the anode comprises a plurality of supporting elements to fix the anode in a mounting position, wherein the supporting elements are made from an electrical in- sulation material, preferably a ceramic material.