Vacuum pump

Abstract

A vacuum pump includes: a sputter ion pump (SIP) module having a first end and a second end; a non-evaporable getter (NEG) module connected to a second end of the SIP module; an electrical lead of the NEG module extends from a first end to a second end of the SIP module; wherein the SIP module comprises an anode having a first surface and an opposing second surface, where at least one cylindrical opening extends from the first surface to the second surface, where the anode further comprises a side surface extending from the first surface to the second surface, where an electrical lead is arranged at the side surface of the anode.

Description

Technical Field

[0001] The present invention relates to a vacuum pump, and more particularly to a vacuum pump including a sputtering ion pump (SIP) module and a non-evaporable getter (NEG) module. Background Art

[0002] A commonly known SIP comprises one or more anodes constructed as tubes or cylindrical openings, wherein a magnetic field is oriented parallel to the central axis of the tube. The anode is surrounded by a cathode element. In particular, the cathode element is arranged relative to the cylindrical opening of the anode at a certain distance along the central axis. A strong electric field is generated between the anode and the cathode. Due to the magnetic field, the path of electrons in the anode unit is enhanced, which leads to ionization of gas atoms and molecules in the vacuum chamber. The generated ions are accelerated and collide with the cathode element. When the accelerated ions impact the cathode element, they will be buried in the cathode material or sputter the cathode material onto other surfaces of the pump. The continuously sputtered chemically active cathode material acts as a getter, which then evacuates the gas by both chemical adsorption and physical adsorption, resulting in a net pumping action.

[0003] It is known in the prior art to combine a SIP with a NEG pump. A NEG module typically comprises a heater element and at least one (and preferably multiple) NEG elements arranged around the heater. The NEG elements can be activated or reactivated during operation by heating them via the heater element.

[0004] When combining a SIP module with a NEG module, electrical connections to the heater elements are necessary. This wiring requires additional space, which is limited in a vacuum chamber. However, routing the electrical connections through the SIP's volume can have drawbacks: sputtered elements from the SIP module can reach the NEG module's electrical leads and create a short circuit between the SIP's anode and ground components, shortening the SIP's lifespan. Therefore, conventional methods often employ separate SIP and NEG modules, increasing the space required within the vacuum chamber. Summary of the Invention

[0005] It is an object of the present invention to provide a compact vacuum pump which can operate more reliably over a longer period of time.

[0006] This problem is solved by a vacuum pump according to claim 1 .

[0007] A vacuum pump according to the present invention includes a sputtering ion pump (SIP) module having a first end and a second end. Furthermore, the vacuum pump includes a non-evaporable getter (NEG) module connected to the second end of the SIP module. Thus, the SIP module and the NEG module are arranged in a stacked manner to form a compact vacuum pump that can be inserted into a vacuum chamber of a vacuum apparatus with a reduced footprint. In particular, the NEG module can be directly connected to the top of the SIP module. Alternatively, the NEG module can be connected to the top of the SIP module via an intermediate element to facilitate connection between the NEG module and the SIP module.

[0008] According to the present invention, the electrical leads of the NEG module extend from the first end to the second end of the SIP module. The SIP module includes an anode having a first surface and an opposing second surface, with at least one cylindrical opening extending from the first surface to the second surface. This cylindrical opening is considered the anode element of the SIP module and is used for the pumping function of the SIP module. The anode also includes a side surface extending from the first surface to the second surface. The electrical leads of the NEG module extending from the first end to the second end of the SIP module are arranged at, and preferably in direct contact with, the side surface of the anode. Thus, the electrical leads are integrated into the SIP module and routed through the SIP module, thereby providing a small and compact vacuum pump. However, since the electrical leads are arranged at the side surface of the anode, they are protected from sputtering from the SIP module. Thus, the anode itself shields the electrical leads from material from the cathode component of the SIP module that sputters onto or near the electrical leads. This prevents sputtered metal from bridging the gap between the anode and the ground component via the electrical leads, thereby reducing the possibility of a short circuit between the anode of the SIP module and the ground component of the SIP module. The vacuum pump, and in particular the SIP module, can operate for a long time without any problems.

[0009] Preferably, there is no line of sight between the cathode and the electrical leads of the SIP module. More specifically, there is no line of sight between the projection of the anode onto the cathode and the electrical leads. A straight line cannot be drawn from the diameter of the anode unit projected onto the cathode to the electrical leads without crossing another surface. This significantly reduces the likelihood that sputtered cathode material will coat the electrical leads with conductive material.

[0010] Preferably, the anode of the SIP module blocks the straight line between the cathode and the electrical lead.Thus, the anode itself blocks any line of sight between the cathode and the electrical lead.

[0011] Preferably, the anode width of the SIP module (i.e., the distance from the first surface to the second surface or the length of the corresponding anode unit) is between 10 mm and 50 mm, more preferably between 15 mm and 30 mm, and most preferably between 15 mm and 20 mm. Due to the width of the anode, sufficient shielding can be provided for the electrical leads so that the cathode material does not sputter onto the electrical leads.

[0012] Preferably, the electrical leads are routed through the SIP module. In particular, the electrical leads are routed through the SIP module or the active volume or pumping volume of the SIP module. Thus, by integrating the electrical leads into the external structure of the SIP module or the pumping volume, a compact design for the SIP module and the entire vacuum pump can be achieved. This is possible because the electrical leads are shielded by the anode itself, and the likelihood of material from the SIP module's cathode sputtering onto the electrical leads is reduced.

[0013] Preferably, the electrical lead is surrounded by an insulator (preferably a ceramic insulator). Through the insulator, direct contact between the electrical lead and the anode is possible, and the electrical lead can be arranged in direct contact with the anode without generating a short circuit.

[0014] Preferably, the electrical lead has at least two wires. In particular, two wires are required because the heating element of the NEG module can be connected via the electrical lead. Each wire can be surrounded by an insulator (preferably a ceramic insulator).

[0015] The anode of the SIP module preferably has at least one or more recesses, within which the electrical leads are arranged. Specifically, the number of recesses is equal to the number of wires in the electrical leads. These recesses allow the electrical leads to be placed closer to the anode, preventing direct line of sight between the electrical leads and the cathode of the SIP module. This also enhances the structural stability of the electrical leads. This is particularly important when the electrical leads are surrounded by fragile ceramic insulators that require structural stability.

[0016] Preferably, the outer structure of the SIP module and / or the outer structure of the NEG module is cylindrical. In the case of the SIP module, the outer structure can be provided by a shell having a cylindrical shape. The outer structure can be an outer shell, which can be vacuum-tight or not. The outer shell enables the SIP module and / or NEG module to function properly and preferably provides a means for connecting a vacuum pump to a vacuum device or a vacuum chamber. Alternatively, the outer structure surrounds the elements of the SIP module and / or NEG module and is constructed to be insertable into a vacuum device or a vacuum chamber. The outer structure can include an opening to allow gas to enter the SIP module or NEG module.

[0017] Preferably, the outer surface of the SIP module and the outer surface of the NEG module (in particular the outer surfaces of the respective outer structures) are flush with each other, thereby providing an overall cylindrical shape of the vacuum pump.

[0018] Preferably, the vacuum pump comprises a flange, wherein the SIP module is connected to the flange at its first end and preferably to the NEG module at its second end. In particular, the SIP module is directly connected to the flange via its base element, and the NEG module is connected to the SIP module via its top element. Alternatively, the base element may also be a flange for connecting the SIP / NEG module to a vacuum device or vacuum chamber.

[0019] Preferably, the SIP module and the NEG module are arranged in the flange area, so that the SIP module and the NEG module can be inserted together into the vacuum chamber and fixed to the vacuum chamber via the flange.

[0020] Preferably, the NEG module and / or SIP module are completely housed within the vacuum environment. In particular, due to their small build dimensions, both the NEG module and the SIP module can be inserted into a vacuum chamber and connected to the chamber via flanges. Therefore, the vacuum chamber housing the vacuum pump does not increase the volume of the vacuum chamber. Furthermore, the present invention reduces the number of parts within the vacuum chamber compared to a standard ion pump design modified to accommodate flange mounting. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The present invention will be described in more detail below with reference to the accompanying drawings.

[0022] Figure 1 is a vacuum pump according to the present invention,

[0023] Figure 2 for Figure 1 Cross-sectional view of a vacuum pump.

[0024] Figure 3 for Figure 1 The frame structure of the vacuum pump,

[0025] Figure 4A and 4B for Figure 1 The frame structure and anode of the vacuum pump,

[0026] Figures 5A-5C for Figure 1 The shell components of the vacuum pump,

[0027] Figure 6A and 6B is a cross-sectional view of a non-evaporable getter module.

[0028] Figure 7 is a connecting element according to the present invention,

[0029] Figure 8A and 8B is an insulating element according to the present invention.

[0030] Figure 9 Based on Figure 1 Cross-sectional view of the SIP module. DETAILED DESCRIPTION

[0031] refer to Figure 1 , shows a vacuum pump 10 according to the present invention. Therein, the vacuum pump 10 includes a non-evaporable getter (NEG) module 12, a sputtering ion pump (SIP) module 14 and a vacuum flange 16. The SIP module 14 is directly connected to the flange 16, and the NEG module 12 is attached to the SIP module 14 opposite to the flange 16. The vacuum pump 10, and in particular the NEG module 12 and the SIP module 14, both have a cylindrical shape. The shape of the SIP module 14 matches the shape of the NEG module 12, so that the SIP module 14 and the NEG module 12 can have a substantially similar or identical outer shape, or at least a substantially similar or identical cross-sectional area. Although in the figure below, the vacuum pump has a cylindrical shape, other shapes are also possible.

[0032] The NEG module 12 and the SIP module 14 are arranged in the region of the flange 16 and can be fully inserted into the vacuum chamber for pumping.

[0033] refer to Figure 2 The SIP module 14 is shown in cross-section and includes an anode 20. Figure 2 In the example shown, the anode has three cylindrical openings or tubes. Other numbers of tubes are also possible. A cathode 18 is provided at the axial ends of these openings. The anode 20 is maintained at a high potential by a high-voltage (HV) conductor 28, which is guided through the flange and connected to the anode via a vacuum feedthrough 26. The flange 16 also includes a connector 68, which is connected to a heating element 32 of the NEG module 12 via electrical leads 30. A NEG element 34 is arranged on the heating element 32 for reactivating the NEG material by heating.

[0034] Here and below, the axial direction of the SIP and its components is defined as along the anode from its lower side to its upper side.Here and below, the lateral direction refers to the direction perpendicular to the axial direction of the anode.

[0035] refer to Figure 3, shows a frame structure 48 of the SIP module. The frame structure 48 includes a base element 50 that can be attached to the flange 16 by welding, brazing, soldering, screws, or any other releasable connection means. In other embodiments, the flange 16 and the base 50 are integrally constructed, or the base element 50 can be provided by the flange 16 itself. Figure 3 In the example shown, two frame side elements 24 are connected to a base element 50, which are constructed as shoulder screws or posts that extend from the base element 50 to the top element 52. The NEG module 12 can be connected to the top element 52 by welding, brazing, soldering, screws, or any other releasable connection means. During assembly, the anode 20 is fixed within the frame structure 48, and then the frame structure 48 and the anode 20 are connected together to the flange 16. This shows Figure 4A and 4B The anode 20 is connected to the frame structure 48 via a lower support element 71, which is provided by an insulating element 62 connected to the anode 20. Furthermore, an upper support element 73 is provided by an insulating element 74. The insulating elements 62 and 74 are constructed of an insulating material, such as a ceramic material. The lower insulating support 71 restricts the anode 20 from moving downward toward the flange 16 and may restrict lateral movement (i.e., movement in one or more other directions or all other directions). The upper support element 73 restricts the anode 20 from moving upward and laterally (i.e., movement in one or more other directions or all other directions). At least one or both support elements 71 and 73 may not completely restrict lateral movement, thereby allowing the anode to move slightly laterally when connecting the anode to the HV conductor 28, thereby facilitating installation of the HV conductor 28 onto the anode 20. Thus, a secure connection between the HV conductor 28 and the anode 20 is possible, and slight manufacturing deviations can be compensated for. In order to completely prevent the movement of the anode 20 and to fix the position of the anode in the frame structure, the anode 20 is connected to the HV conductor 28 extending through the opening in the base element 50, connecting the anode 20 to the HV conductor 28 of the vacuum feedthrough 26 via the conductive sleeve 49. Thus, the anode 20 is fixed in its position within the frame structure 48 of the SIP module 14 by the lower support element 71, the upper support element 73 and the connection to the HV conductor 28 of the electrical feedthrough 26.

[0036] Therefore, the steps of assembling the SIP module 14 include:

[0037] a) providing a frame structure preferably comprising a base element 50,

[0038] Connecting one or more frame side members 24 to the base member and may also include a top member 52 connected to a respective frame side member 24,

[0039] b) inserting the anode and connecting the anode to the frame structure via the lower support element 71 and the upper support element 73,

[0040] c) attaching the frame structure 48 together with the anode 20 to the flange 16 , thereby connecting the anode 20 to the electrical feedthrough 26 and simultaneously fixing the position of the anode 20 in the SIP module 14 ,

[0041] d) Attaching the shell around the frame structure 48 as explained in more detail below.

[0042] refer to Figures 5A to 5C , shows details of the housing of the vacuum pump 10. The housing of the vacuum pump 10, and in particular the housing of the SIP module 14, comprises two separate housing elements 22. In this embodiment, each housing element 22 is constructed identically, but the housing elements 22 can also be constructed / designed differently. Each housing element 22 comprises at least one magnet 78, wherein Figures 5A to 5C In the example of , each shell element 22 includes two magnets 78. The magnets 78 are arranged in recesses 79 of the shell element 22 to prevent lateral movement. The size of the recess 79 is adapted to the size of the magnet so that the side walls of the recess 79 directly contact the side walls of the corresponding magnets 78. The magnets 78 are attached to the corresponding shell element 22 only by their magnetic force. There are no additional fixing / fastening elements. Therefore, the shell element 22 serves as both the pole shoe and the external structure of the SIP module 14. The pole shoe guides the magnetic flux through the SIP module 14, and the external structure provides structural stability for the SIP module 14. Therefore, the shell element 22 is made of a magnetic material (such as mild steel). The magnets 78 are neodymium (Nd) magnets or samarium (Sa) cobalt (Co) magnets. The magnets are attached to the shell element 22 with one surface. The opposite surface of the magnets 78 is directly connected to the cathode 18. The cathode 18 is plate-shaped and covers the entire or substantially entire surface of the magnets 78. The cathode 18 can be made of titanium (Ti) or tantalum (Ta). The two shell elements 22 can include cathode elements 18 and 18' made of the same material or different materials. To secure the cathode 18 in place, a bracket or clamping element 80 is provided at the upper and lower ends of the corresponding magnet 78. The bracket element 80 is held in place by the magnetic force of the magnet 78. No additional fixing elements are required. The bracket element 80 includes a chamfered surface 84, which is chamfered toward the magnet 78. Similarly, the cathode element 18 includes a chamfered edge 82, which is chamfered away from the magnet 78 and corresponds to the chamfered surface 84 of the bracket element 80. When the bracket element 80 is attached to the side of the magnet 78, a clamping force is applied to the cathode 18 to secure the position of the cathode 18. The surface of the cathode element 18 is flush with the corresponding bracket element 80, and therefore it is possible to tightly position the cathode element 18 to the anode 20. In addition, the assembly and disassembly of the cathode element 18 can be completed without additional tools.

[0043] The two shell elements 22 have a similar shape to the outer shape of the SIP module 14. The shell elements 22 have openings 23 to allow gas molecules and particles to enter the active volume of the SIP module. The present invention is not limited by the number or shape of these openings 23. To provide sufficient stability for the shell elements, the shell elements 22 are provided with recesses 81 along the axial direction of the shell elements 22 at their axial edges. These recesses 81 accommodate the frame side elements 24 when attached to the shell elements 22. Thus, the corresponding shape of the recesses 81 determines the position of the elements 22 by the position of the frame side elements 24.

[0044] refer to Figure 6A and 6B , shows a NEG module 12 including a heater 32 with a heating wire 86. The NEG module 12 includes a base member 88 and a top member 90, wherein the NEG element 34 is positioned over the heater 32. The top member 90 and the base member 88 can be connected by NEG side members, such as shoulder screws or posts. In particular, the NEG side members are constructed from threaded rods or posts. Electrical connection to the heater 32 is provided by an electrical connector 38 having a connecting member 94. Figure 7 The connecting element 94 is shown in more detail in FIG. The connecting element 94 includes a first end 96 and a second end 98. There is a collar or protruding feature 100 between the first end 96 and the second end 98. Although Figure 7 , the first end 96 and the second end 98 may have the same diameter, but the present invention is not limited to this example, and different diameters of the first end 96 and the second end 98 will also be possible. Figure 7 The example of φ shows a circular cross section, wherein other shapes are of course also possible.

[0045] Connector 38 includes insulating elements 102 and 106, such as Figure 8A and 8B As shown. The first insulating element 102 has openings 104. The number of openings 104 corresponds to the number of connecting elements 94. The diameter of the openings 104 corresponds to the diameter of the first end 96, and the insulating element 102 is preferably made of a ceramic material. Similarly, the second insulating element 106 is made of a ceramic material. The second insulating element 106 is constructed of two halves, wherein Figure 8BOnly a single half is shown. An opening 108 is established through the two halves of the insulating element 106, wherein the diameter of the opening 108 corresponds to the diameter of the second end 98 of the connecting element 94. The connecting element 94 is crimped or otherwise attached to the heating wire 86 of the heater 32. Subsequently, the two halves of the second insulating element are inserted into the housing of the base element 88 of the NEG module 12 and placed on the shoulder 95. Wherein, due to the protruding features 100, the connecting element 94 will not fall through the opening 108 of the second insulating element 106. Subsequently, the first insulating element 102 is assembled by inserting the first end 96 of the connecting element 94 into the corresponding opening 104. Due to the protruding features 100, the connecting element 94 will not fall from the first insulating element 102. The first insulating element 102 and the second insulating element 106 are fixed in their positions by fixing elements (for example, provided by set screws). Therefore, no clamping force acts directly on the connecting element 94. Due to the protruding features 100 , the fixing element 94 is fixed in its axial position, wherein a slight lateral movement of the connecting element 94 is still allowed and helps during assembly of the NEG module 12 .

[0046] Similar to the connector 38 that connects the NEG module 12 to the SIP module 14, a connector 40 is provided to connect the SIP module to the flange 16, as shown. Figure 4A and 4B Thus, electrical leads 30 connected to the heater 32 extend from the flange 16 through the complete SIP module 14 and via the connector 38 to the NEG module 12. The electrical leads 30 may be composed of two wires 110 and 110' that are surrounded by an insulating material, such as a ceramic material.

[0047] The following will refer to Figure 9, shows a cross-sectional top view of a SIP module 14. Anode 20 has a first surface 114 and an opposing second surface 118, which correspond to the axial direction of the cylindrical opening in anode 20. First surface 114 and second surface 118 are connected by a side surface 116, along which electrical lead 30 extends. Due to the location of electrical lead 30, there is no direct line of sight 112 between cathode element 18 and electrical lead 30, thereby preventing or at least reducing the possibility of cathode 18 material splashing onto the surface of electrical lead 30 (which could create a short circuit). Thus, electrical lead 30 is protected by anode 20 itself. Accordingly, side surface 116 of the anode may include a recess 120 that accommodates electrical lead 30 and its corresponding wires 110, 110'. The low voltage power supply for the heater 32 of the NEG module 12 thus extends from the connector 68 via the connecting element 40 and the electrical leads 30, through the SIP module 14, and in particular within the pole piece of the SIP module provided by the shell element 22, towards the connector 38 at the SIP module top element 52, and then further to the connector 38 and the heater 32.

[0048] Thus, the vacuum pump according to the present invention provides a combination of a NEG module and a SIP module, both of which can be fully inserted into a vacuum chamber having a small cross-sectional area. Simultaneously, the implementation of the frame structure 48 and the housing simplifies the assembly process of the SIP module 14 and reduces the number of parts required in the vacuum environment.

[0049] Reference Signs List

[0050] 10 Vacuum pump

[0051] 12 NEG modules

[0052] 14 SIP modules

[0053] 16 Flange

[0054] 18, 18' cathode element

[0055] 20 Anode

[0056] 22 Shell Components

[0057] 23 Opening

[0058] 24 Frame side members

[0059] 26 Vacuum feedthrough

[0060] 28 HV conductor

[0061] 30 electrical leads

[0062] 32 Heating Elements

[0063] 34 NEG components

[0064] 38 connectors

[0065] 40 connectors

[0066] 48 frame structure

[0067] 49 Conductive Sleeve

[0068] 50 base element

[0069] 52 top element

[0070] 62 Insulation elements

[0071] 68 connector

[0072] 71 Lower support element

[0073] 73 Upper support element

[0074] 74 Insulation elements

[0075] 78 magnets

[0076] 79 recess

[0077] 80 bracket elements

[0078] 81 Notch

[0079] 82 Chamfered Edges

[0080] 84 Chamfered surface

[0081] 86 heating wire

[0082] 88 base element

[0083] 90 top element

[0084] 94 connecting elements

[0085] 95 Shoulders

[0086] 96 first end

[0087] 97 fixing element

[0088] 98 Second end

[0089] 100 outstanding features

[0090] 102 first insulating element

[0091] 104 Opening

[0092] 106 second insulating element

[0093] 108 Opening

[0094] 110, 110' wire

[0095] 112 Sight

[0096] 114 first surface

[0097] 116 side surface

[0098] 118 Second Surface

[0099] 120 notch

Claims

1. A vacuum pump comprising: A sputter ion pump SIP module having a first end and a second end; a non-evaporable getter (NEG) module connected to the second end of the SIP module; an electrical lead of the NEG module extending from the first end to the second end of the SIP module; wherein the SIP module comprises an anode having a first surface and an opposing second surface, wherein at least one cylindrical opening extends from the first surface to the second surface, wherein the anode further comprises a side surface extending from the first surface to the second surface, The electrical lead is arranged at a side surface of the anode.

2. The vacuum pump according to claim 1, wherein There is no line of sight between the cathode of the SIP module and the electrical leads, and in particular there is no line of sight between the cathode and the projection of the anode on the electrical leads.

3. The vacuum pump according to claim 1 or 2, wherein: The anode of the SIP module blocks the straight line between the cathode and the electrical lead.

4. The vacuum pump according to any one of claims 1 to 3, wherein The anode of the SIP module has a width between 10 mm and 50 mm, more preferably between 15 mm and 30 mm, and most preferably between 15 mm and 20 mm.

5. The vacuum pump according to any one of claims 1 to 4, wherein The electrical leads are arranged within the SIP module.

6. The vacuum pump according to any one of claims 1 to 5, wherein The electrical leads are surrounded by an insulator, preferably a ceramic insulator.

7. The vacuum pump according to any one of claims 1 to 6, wherein The electrical lead has at least two wires.

8. The vacuum pump according to any one of claims 1 to 7, wherein The anode of the SIP module has at least one or more recesses, wherein the electrical leads are arranged in the recesses.

9. The vacuum pump according to any one of claims 1 to 8, wherein The outer structure of the SIP module and / or the outer structure of the NEG module is cylindrical.

10. The vacuum pump according to any one of claims 1 to 9, wherein An outer surface of the SIP module and an outer surface of the NEG module are flush with each other.

11. The vacuum pump according to any one of claims 1 to 10, comprising a flange, wherein: The SIP module is connected with its first end to the flange, and / or wherein the NEG module and the SIP module are arranged in the region of the flange.

12. The vacuum pump according to any one of claims 1 to 11, wherein The NEG module and / or the SIP module are arranged completely within a vacuum.

Images