Partially sealed ion guide and ion beam deposition system

Abstract

Disclosed herein is an ion guide for guiding an ion beam along an ion path, the ion guide having a longitudinal axis corresponding to the ion path. The ion guide includes a plurality of electrode plates arranged perpendicular to the longitudinal axis, each electrode plate having an opening and arranged so that the longitudinal axis extends through its respective opening, wherein the openings collectively define an ion guide volume. The ion guide extends or is configured to extend through a separation wall separating an adjacent first pumping chamber and a second pumping chamber. The ion guide has a first portion in which a gap is formed between at least some of the electrode plates so that uncharged gas can escape from the ion guide volume, wherein the first portion is entirely located in the first pumping chamber. A second portion prevents neutral gas from escaping from the ion guide volume between adjacent electrode plates, in which a sealing element is arranged between adjacent electrode plates, and the second portion extends at least from the separation wall into the second pumping chamber.

Description

Technical Field

[0001] The present invention relates to an ion guide for guiding an ion beam along a path. In particular, the present invention relates to an ion guide for use in an ion beam deposition system or related applications, and to an ion beam deposition system including such an ion guide, and to a method for guiding ions using such an ion guide. Background Art

[0002] Ion beams have many uses in various fields of natural science and technology, including experimental physics, medical devices, electronic component manufacturing or life sciences, especially mass spectrometry, where charged molecules (ions) are guided to, from or within a mass spectrometer or collision cell. The general purpose of an ion guide is to confine the ion beam along a predetermined path of the ion beam, usually using a plurality of electrodes arranged around the ion path, which combine to produce an electric potential to guide the ions. In the simplest case, the electric potential can be a static DC potential, which will usually be implemented as an ion single lens arrangement. However, this requires that the radial and axial momentum of the ions have a fixed correlation to keep them on track. Any disruption of this correlation (e.g. due to collisions with residual gas atoms) will cause the ions to turn and deviate from the track. These situations are very common in the first stage of a multi-stage ion guide system or in a collision cell or drift cell at relatively high pressures, but may also occur due to space charge effects in later stages.

[0003] To make the ion guide more resistant to such interference, an electrode system can be employed that is driven by a radio frequency (RF) voltage having a frequency of about 0.5 to 5 MHz and an amplitude of a few volts up to about 100 volts. When the amplitude and frequency of the RF potential are properly chosen, the ions will be effectively repelled from the RF electrodes by an effective potential or "pseudo-potential" that reflects the effect of the RF electric field averaged over many AC cycles on the ions. The repulsive force that can be derived from this pseudo-potential, the so-called "field gradient force", is proportional to the gradient of the square of the RF field strength, is proportional to the square of the ion charge and is therefore independent of the polarity of the ion charge, and is inversely proportional to the ion mass and the square of the RF frequency.

[0004] In most RF-operated ion guide systems, adjacent electrodes are driven by sinusoidal voltages of opposite phase (i.e., with a 180° phase shift between them). For example, in known multipole ion guides, four, six, or eight rod electrodes may be arranged in a circle extending around and parallel to the ion path, thereby forming a quadrupole, hexapole, or octopole structure, respectively. In a different design, known in the art as a stacked ring ion guide, multiple ring electrodes are stacked to form a tubular structure, and every two adjacent ring electrodes are driven by antiphase voltages, thereby confining ions to a volume extending through the rings.

[0005] Although ion guides have many purposes in various fields of science and technology, and the present invention is not limited to use in a particular one of them, the ion guide of the present invention is particularly suitable for use in ion beam deposition (IBD), mass spectrometry (MS) (such as triple quadrupole, orbital trap or quadrupole time-of-flight (Q-TOF) mass spectrometry) or ion mobility spectrometry (IMS) systems.

[0006] In IBD, ions are guided through a series of pumping chambers along the ion path with gradually reduced pressure before being deposited on a substrate or target by means of so-called "soft landing". The purpose of the pumping chambers is to remove unwanted neutral particles from the ion beam. Ion beam deposition has important advantages over conventional deposition techniques. For example, unlike sputtering, plasma spraying, physical vapor deposition (PVD) and atomic layer deposition (ALD), IBD is not limited to the deposition of thermally stable molecules. Chemical vapor deposition (CVD) requires chemical reactions between the sometimes toxic eductants on the substrate, which can also be avoided using IBD. Finally, while spin coating is limited to large thicknesses (on an atomic scale), IBD allows the deposition of layers with defined atomic thicknesses.

[0007] Furthermore, since the ion beam can be deflected using appropriate electric fields, in IBD it is possible to "write" structures on the substrate in a process similar to mask-free ion beam lithography. It is thus possible to position low-mass, highly sensitive, thermally labile molecules such as amino acids up to high-mass molecules such as peptides, proteins or even DNA molecules with layer thicknesses defined at the atomic scale in microarrays for the fabrication of assays, sensors or highly specific catalysts.

[0008] All of these advantages of IBD currently come at the expense of rather slow deposition rates due to the limited throughput of IBD systems given the relatively low intensity of the ion beams in current IBD systems.

[0009] US2018 / 076014 A1 discloses a system and method for sample analysis using sub-atmospheric pressure (sub-AP) laser ionization. The sub-AP ion source includes: a holder having a sample containing analyte molecules; a pulsed laser beam configured to produce ionized matter from the sample; an ion extractor adjacent to the holder, configured to extract analyte ions from the ionized matter through an extraction electric field near the sample; and an ion funnel structure consisting of an orifice plate electrode positioned along the ion funnel passage direction z. The ion funnel structure has an inlet and an outlet, the outlet being the electrode with the smallest hole in the structure. This structure is configured to receive analyte ions from the ion extractor at the inlet and drag them toward the outlet using an axial electric field. The extraction electric field is at least partially electrically shielded from the axial electric field.

[0010] US2002 / 063207 A1 discloses a mass spectrometer comprising an ion guide spanning two or more vacuum chambers. The ion guide comprises a plurality of electrodes having apertures. One of the electrodes may also form a differential pumping aperture separating the two vacuum chambers.

[0011] GB 2416913 A discloses a centrifugal particle mass analyzer, which removes particles other than those with a desired mass-to-charge ratio from an aerosol by holding the desired particles in a rotating flow between two electrodes (between which an electric field exists), forming a classifier channel between them. Other particles impact the electrodes. The analyzer is constructed so that the electric field is not inversely proportional to the centripetal acceleration required for the particles, thereby providing a stable classification of the particles. The electrodes are supported on bases that serve as side walls of the classifier channel. These bases are made of a material that allows a strong electric field to be applied between the electrodes but prevents static charge from accumulating on the side walls, such as a material with a resistivity of 10 9 with 10 12 Ohm.cm static dissipation plastic.

[0012] US2017 / 350860 A1 discloses a trapped ion mobility spectrometer, and proposes to use a high-order (N>2 order) linear multipole RF system to accumulate and analyze ions at a DC electric field barrier, a pure high-order RF multipole system or a multipole RF system that transitions from high order to low order, such as transitioning from a linear octupole RF system (N=4) to a linear quadrupole RF system (N=2) in front of the DC electric field barrier apex. The RF ion guide of the TIMS device is constructed by rolling or folding a printed circuit board (PCB) carrying electrodes, which are used to generate a radial RF field and an axial DC field. The surface of the PCB is covered with a high-resistance coating to prevent ion charging, wherein the envisioned specific surface resistance is 10 9 with 10 12 Ohm. Summary of the invention

[0013] The problem underlying the present invention is to provide an ion guide having improved properties, in particular allowing to increase the throughput of an IBD system, and an improved IBD system, as well as a method for guiding an ion beam along an ion path.

[0014] This problem is solved by an ion guide, an ion beam deposition system, a method for guiding an ion beam along an ion path, an ion guide and a suitable manufacturing method.

[0015] According to one aspect of the present invention, there is provided an ion guide for guiding an ion beam along an ion path, the ion guide having a longitudinal axis corresponding to the ion path, wherein the ion guide comprises a plurality of electrode plates arranged perpendicular to the longitudinal axis, each electrode plate having an opening and arranged so that the longitudinal axis extends through its respective opening, wherein the openings together define an ion guide volume. In operation, the electrode plates are connected to an RF drive source for driving two adjacent electrode plates with voltages of opposite polarity. The ion guide of the present invention extends or is configured to extend through a separation wall separating adjacent first and second pumping chambers. The ion guide has: a first portion, in which gaps are formed between at least some of the electrode plates so that uncharged gas can escape from the ion guide volume, wherein the first portion is entirely located or configured to be located in the first pumping chamber; and a second portion, in which a sealing element is arranged between adjacent electrode plates to prevent neutral gas from escaping from the ion guide volume between adjacent electrode plates, and the second portion extends at least from the separation wall into the second pumping chamber.

[0016] The yield of an IBD system or related system that employs an ion beam directed through a plurality of consecutive pumping chambers is controlled by the ion current that can be directed through the ion guide system, which is referred to herein as the "current capacity" of the ion guide or ion guide system. An obvious way to increase the current capacity is to increase the diameter of an ion guide or a plurality of ion guides as a whole. However, ion guides with larger diameters will naturally have larger holes in the separation wall through which ions are directed from one pumping chamber to another. This in turn makes it more difficult to reduce the number of neutral particles in the ion beam by pumping. The flow of neutral particles together with the ion beam is referred to as "gas load" below. In other words, the inventors have noticed that when the diameter of the holes in the separation wall is increased, more pumping stages are ultimately required to reduce the gas load to the desired extent. However, a larger number of pumping chambers increases manufacturing and operating costs and lengthens the ion path, resulting in an inherent increase in ion losses. In other words, for a favorable ion guide system, it would be desirable to increase the current capacity while keeping the gas load low.

[0017] In this respect, the ion guide of the present invention has proven to be particularly advantageous. In contrast to typical ion guide systems involving a plurality of consecutive pumping chambers, in which a separate ion guide is provided in each chamber, the ion guide of the present invention extends through a separation wall separating adjacent pumping chambers, thus allowing optimal guidance of the ions at the most critical points, i.e. at the transitions between adjacent pumping chambers, thereby avoiding ion losses.

[0018] In addition, in order to reduce the gas load, it is important to reduce the gas conductivity of the structure at the interface of the adjacent pumping chambers. If such a structure is a simple opening in the wall, the gas conductivity is approximately proportional to the opening area, at least at medium pressure. However, in the framework of the present invention, the "structure at the interface" is formed by the gas-tight second part of the ion guide, which extends at least from the separating wall into the second pumping chamber. In this article, the term "at least" indicates that the second part may also be partially located in the first pumping chamber. The sealed, gas-tight second part forms a "tube" instead of a simple hole, and the gas conductivity of the tube is significantly reduced compared to the gas conductivity of a simple opening with the same diameter, and in some cases can actually be roughly proportional to the inverse of the length of the second part. The "tubular" structure of the second part is also referred to as a "tunnel" in this article. Therefore, if ions can be safely introduced into the second part or "tunnel" and the loss during the passage through the tunnel is avoided or minimized, the current capacity can be maintained while reducing the gas load.

[0019] The first portion of the ion guide facilitates safe introduction of ions into the second portion or "tunnel", which allows for receiving ions and directing them into the tunnel while allowing for removal of neutral gases through the gap between the electrode plates. The first gas permeable portion of the ion guide is also referred to herein as a "funnel" because it is used to direct ions into the gas-tight second portion or tunnel. This may, but need not necessarily, include electrode plates in the first portion to define a tapered or funnel-shaped ion guide volume, which is referred to herein as a "funnel structure". Since the ion guide of the present invention includes both a tunnel section combined with a funnel section, the ion guide is also referred to herein as a "TWIN ion guide".

[0020] In a preferred embodiment, some or all of the sealing elements are made of a material having a resistivity between 10 2 Ohm·cm and 10 12 Ohm·cm, preferably between 3×10 5 Ohm·cm and 10 9 Ohm·cm, or have a resistivity between 104 Ohm and 10 14 Ohm, preferably between 3×10 7 Ohm and 10 10 The intermediate resistivity material has sufficient resistance to keep the current between adjacent electrode plates within a tolerable range when RF driven, while allowing the charge of stray ions that may strike the seal element during operation to be discharged. In this way, the seal element is prevented from being charged by stray ions from the ion beam, which would cause distortion of the electric field used to guide the ion beam and thus reduce the current capacity.

[0021] However, if the surface facing the ion volume, preferably any surface facing the ion guide volume, has a 4 Ohm and 10 14 Ohm, preferably between 3×10 7 Ohm and 10 10 Ohm, then appropriate charge discharge can also be achieved. Such surface resistivities can be obtained using the above-mentioned intermediate resistivity materials, but can also be obtained by appropriately coating the support with a coating of suitable conductivity, where the support can then be, for example, an electrical insulator.

[0022] In a preferred embodiment, the intermediate resistivity material is a plastic material or a ceramic material comprising or mixed with conductive particles, in particular metal or graphite particles. In this document, the term "particle" should have a broad meaning and does not imply any particular geometry. In particular, the term "particle" should cover, for example, elongated particles with a high aspect ratio, such as nanowires, etc. In addition or alternatively, ferrite-based materials can be used. It is important that the resistivity of the intermediate resistivity material does not change significantly with temperature, or that the resistivity values ​​fall within the above-mentioned boundaries over the entire temperature range that the sealing element may obtain during normal operation of the ion guide. Temperature changes are expected to occur due to the heating of the electrode plates caused by the RF current, and since ion guides are typically used in a vacuum, there is no convection cooling. Therefore, it is not preferred to use conventional semiconductor materials as intermediate resistivity materials because the resistance tends to drop too much during heating during operation of the ion guide.

[0023] In a preferred embodiment, the intermediate resistivity material is a material suitable for 3D printing, and specifically a plastic material mixed with graphene, carbon nanotubes, carbon fibers, carbon black, graphite, or metal, or a ceramic material mixed with metal or metal oxide.

[0024] In a preferred embodiment, some or all of the sealing elements are coated with a coating suitable for dissipating the charge of stray ions at least on the surface facing the ion guide volume, preferably on any surface facing the ion guide volume, thereby avoiding electrostatic charging of the sealing elements caused by stray ions.

[0025] Herein, the coating may be a metal film with a thickness of 30 to 1000 nm, or a slurry containing glass and metal oxide, wherein the thickness of the slurry is preferably 5 to 1000 μm. Such a "slurry" is also referred to as "cermet" in the art.

[0026] In a preferred embodiment, at least some of the sealing elements are flush with the openings in one or both of its adjacent electrode plates, or are retracted from the openings in one or both of its adjacent electrode plates in a radially outward direction by less than 3 times, preferably less than 1.5 times and most preferably less than 1.0 times the distance between the corresponding adjacent electrode plates. In an embodiment, when the sealing elements are flush with the openings in the adjacent electrode plates, the total volume of the tunnel is minimal, which again allows low gas conductivity. However, retracting the sealing elements at least a little from the openings in the electrode plates results in a "rough" surface of the channel formed by the second portion, increasing turbulence in the neutral gas flow, thereby further increasing the flow resistance. Since in this embodiment, the sealing elements may extend to or at least approach the ion guide volume, the risk that the sealing elements may be hit by stray ions is increased. However, using the preferred sealing elements made of an intermediate resistivity material or having the above-mentioned thin film resistivity at least at the surface facing the ion guide volume, preferably at any surface facing the ion guide volume, this risk is tolerable because it does not lead to accidental charging of the sealing elements. If the sealing element is retracted far enough in a radially outward direction from the opening in one or both of its adjacent electrode plates, the risk of being struck by stray ions becomes low enough that the sealing element need not have a resistivity or sheet resistivity suitable for expelling ions, but can be formed from an insulating material.

[0027] In a preferred embodiment, at least some of the electrode plates in the second part are also made of a material suitable for 3D printing, specifically a plastic material mixed with graphene, carbon nanotubes, carbon fibers, carbon black, graphite or metal, or a ceramic material mixed with metal or metal oxide. In this way, the entire second part (i.e., the tunnel part) of the ion guide, including the electrode plates and the sealing element, can be manufactured by 3D printing, which greatly reduces the manufacturing cost and workload. Commercially available 3D printing equipment allows adding layers of different materials on top of each other. This generally requires that the melting temperatures of the two materials are at least close to each other so that the lower layer does not melt or soften when the consecutive layer is placed on top of it. When forming the second part of the ion guide, the same or similar plastic material in which different concentrations of conductive particles are dispersed can be used to form the "electrode plate" and the "sealing element" respectively, wherein the "electrode plate" and the "sealing element" correspond to areas of different resistivity within the same printed object. Advantageously, the second part of the ion guide is printed in an upright position, i.e., the longitudinal axis is in the vertical direction, while continuously adding horizontal layers corresponding to the electrode plate and the sealing element respectively. In some embodiments, the electrode plate and the sealing element can be printed, including their openings. With current 3D printing accuracy, this is possible if the diameter of the opening is 1 mm or more and the total length of the second part of the ion guide is, for example, 100 mm. For smaller openings, the openings can be formed later using a high-precision drill. It is also possible to combine the printing procedure including the openings with the drilling procedure, where the openings in the printed electrode plate and the sealing element may not be large enough, but help guide the drill when drilling the subsequent openings. In some embodiments, only the electrode plate and the sealing element are formed by 3D printing, while other components, such as wiring for electrical connection of the electrode plate to the corresponding RF drive source, are added in a conventional manner. This makes the 3D printing process relatively easy and allows for fairly fast manufacturing. However, in other embodiments, additional external wiring can also be manufactured by 3D printing.

[0028] In a preferred embodiment, the sealing element is formed by an annular disk, wherein the annular disk preferably serves as a spacer to adjust the distance between adjacent electrode plates.

[0029] Preferably, in one of the first and second parts, and preferably starting from the first part, the diameter of the openings in at least a subset of the continuous electrode plates decreases in the downstream direction of the ion guide, thereby forming a funnel structure. In this text, if the opening should not be circular, the "diameter" will refer to an effective parameter defined by √A / π, where A is similar to the area of ​​the opening. With this funnel structure, the "blurred" ion beam can be focused before being fed into the second part (i.e., the "tunnel"), which in turn allows the ions to be guided through a relatively narrow tunnel without significant losses, the narrow tunnel allowing reduced gas conductivity and therefore reduced gas loading, as explained above.

[0030] In a preferred embodiment, in at least a portion of said funnel structure, the quotient of the difference between the diameters of the openings in adjacent electrode plates divided by the distance between these adjacent electrode plates tapers in said downstream direction of the ion guide. This allows a smooth transition between the "tapered" funnel structure and the subsequent cylindrical or nearly cylindrical portion of the ion guide, which has been found to further increase the current capacity.

[0031] In a preferred embodiment, the funnel structure is formed primarily in the first portion, but extends into the second portion of the ion guide. It should be noted that in the first portion, the neutral gas flows primarily radially outward through the gaps between adjacent electrode plates, while in the second portion (tunnel), the neutral gas flows only in the longitudinal direction (towards the second chamber). In other words, at the interface between the first and second portions, the direction of the gas flow changes. The inventors have found that the best results in terms of gas loading and current capacity can be obtained if this change in the direction of the gas flow is not consistent with the position where the ion beam has reached its maximum concentration. Therefore, although a funnel structure can be used in the first portion and a cylindrical structure in the second portion, in a preferred embodiment, the funnel structure actually extends into the second portion so that the ion beam is maximally concentrated only after the change in the direction of the gas flow from radial to longitudinal occurs.

[0032] In a preferred embodiment, no DC lens is arranged between the first and second parts of the ion guide. In fact, in the ion guides of the prior art, a DC lens is usually provided at its exit, which defines the boundaries of the RF field generated in the ion guide and controls the further flight of ions out of the ion guide, for example by focusing the ion beam. Therefore, these DC lenses are usually called "exit lenses" or "entrance lenses". However, in the present invention, the first and second parts of the ion guide are preferably seamlessly connected, and no such DC exit lens is arranged between the first and second parts. The inventors have found that this design significantly increases the current capacity of the ion guide.

[0033] In a preferred embodiment, the spacing between at least some adjacent electrode plates in the first part is at least 1.5 times, preferably at least 3 times, greater than the spacing between at least some adjacent electrode plates in the second part. In this context, "2 times greater" is equivalent to "twice as large", and "1 time greater" will mean the same spacing. It should be noted that ion clouds with the same polarity in the ion guide will cause radial repulsion forces, and the greater this repulsion force, the more concentrated the ions are in the radial direction. These repulsion forces need to be overcome by the RF field generated by the electrode plates. The strength of the RF field increases as the spacing between adjacent electrode plates decreases. In order to safely confine the ions within the ion guide volume and thus maintain the current capacity, a sufficiently small spacing is required at the area of ​​the ion guide where the ion beam is most concentrated, which applies to the second part of the ion guide. However, at least in a part of the first part, the ion beam is not yet fully focused, resulting in lower repulsion forces, so that a larger electrode plate spacing will be sufficient. This is explained in a preferred embodiment of the present invention, wherein the spacing between at least some adjacent electrode plates in the first part is at least 1.5 times, preferably at least 3 times greater than the spacing between at least some adjacent electrode plates in the second part. By avoiding unnecessary small spacing of electrode plates in areas where they are not needed, the capacitance of the electrode plate assembly and likewise the drive current can be reduced.

[0034] Although the spacing of the electrode plates in the first and second parts of the ion guide may be different, it has proven advantageous to provide a transition region between the first and second parts in which the spacing between adjacent electrode plates is uniform or at least varies by less than 15%, preferably less than 5%. In this context, the transition region preferably comprises at least three electrode plates of the first part. In short, the transition region allows a smooth transition from a larger spacing in the first part to a smaller spacing in the second part, which has been found to allow an improved current capacity.

[0035] In a preferred embodiment, the electrode plates are formed by an annular element comprising two or more radially extending mounting portions connected to corresponding mounting structures, wherein the mounting portions of the odd-numbered electrode plates are connected to one or more first common mounting structures and the mounting portions of the even-numbered electrode plates are connected to one or more second common mounting structures different from the one or more first common mounting structures. As will be explained below with reference to exemplary embodiments, this allows avoiding overlap between mounting portions of adjacent electrode plates driven with opposite polarity and thus allows reducing the capacitance of the ion guide. In a related embodiment, the mounting structure is also used to apply a drive voltage to the electrode plates.

[0036] In a preferred embodiment, the electrode plate is made of copper, molybdenum, tungsten, nickel or a compound or alloy thereof, or made of stainless steel, and / or the electrode plate is plated with silver or gold.

[0037] In various embodiments, the thickness of the electrode plate in the second part of the ion guide is 3 mm or less, preferably 1 mm or less, more preferably 0.3 mm or less, most preferably 0.1 mm or less, and is 0.01 mm or more, preferably 0.02 mm or more and most preferably 0.03 mm or more.

[0038] In a preferred embodiment, the average distance between adjacent electrode plates in the second part of the ion guide is 3 mm or less, preferably 1 mm or less, more preferably 0.3 mm or less, most preferably 0.1 mm or less and is 0.01 mm or more, preferably 0.02 mm or more and most preferably 0.03 mm or more.

[0039] In a preferred embodiment, for at least 10%, more preferably at least 50% of the electrode plates, the ratio of the diameter of the opening in each electrode plate to the distance to one of its adjacent electrode plates is between 2000 and 1.0, preferably between 2000 and 2.0.

[0040] In a preferred embodiment, the electrode plate is connected to an RF drive source, which is configured to drive two adjacent electrode plates with voltages of opposite polarity and freely adjustable radio frequencies. In this article, "driven with opposite polarity" generally refers to the voltages at adjacent electrode plates being offset by 180°, so that when the voltage at one electrode plate is positive at a given point in time, the voltage at the electrode plate directly adjacent to it is negative, and vice versa.

[0041] In this article, the RF driving source is preferably configured to drive the electrode plate using an RF square wave signal or a superposition of RF square wave signals. A non-limiting example of a "superposition of square wave signals" is a so-called "digital signal", which corresponds to a superposition of square waves with different amplitudes and different duty cycles but the same fundamental frequency.

[0042] It should be noted that RF square wave drive signals or superpositions thereof are rare in conventional ion guides, in which electrodes are typically resonantly driven using an LC circuit established by adding an inductive element and using the inherent capacitance of the electrode to adjust the resonant frequency. The inventors have noticed that a particular waveform (i.e., a square wave digital waveform as opposed to a sine wave) has little effect on the current capacity of the ion guide, but that a square wave drive signal can be more easily generated at a freely adjustable frequency than a sine wave drive signal. In fact, a square wave signal can be generated simply by using a switching circuit without having to provide any resonant LC element. Since the switching frequency, duty cycle and superposition of square waves can be freely adjusted, the digital waveform or any other superposition of square waves can also be freely adjusted to provide optimal ion guiding performance.

[0043] In a preferred embodiment, the electrode plates are connected to an RF drive source that provides an RF voltage with a frequency freely adjustable between about 0.05 and 20 MHz.

[0044] In order to exert a driving force on the ions in the longitudinal direction of the ion guide, a DC electric field may be established along the centre line of the ion guide. To this end, in a preferred embodiment, a DC potential gradient is established along the length of at least a part of the second portion of the ion guide by means of a DC current passing through corresponding electrode plates and an intermediate resistivity sealing element arranged between them, either through the sheet resistivity of the sealing element or through an external resistor arranged between adjacent electrode plates. Another possible way to establish a DC potential gradient is to use an external resistor between adjacent electrode plates, which may also be applied to the first portion of the ion guide.

[0045] In a preferred embodiment, the ion guide is part of an ion beam deposition system in which an ion beam is guided through a plurality of pumping chambers of decreasing pressure, wherein adjacent pumping chambers are separated by separation walls having apertures for passage of the ion beam.

[0046] Another aspect of the invention relates to an ion beam deposition system comprising at least one ion guide according to one of the above embodiments.

[0047] Another aspect of the present invention relates to a method for guiding an ion beam along an ion path using an ion guide, the ion guide having a longitudinal axis corresponding to the ion path, wherein the ion guide includes a plurality of electrode plates arranged perpendicular to the longitudinal axis, each electrode plate having an opening and arranged so that the longitudinal axis extends through its respective opening, wherein the openings collectively define an ion guide volume, wherein the ion guide extends through a separation wall separating adjacent first and second pumping chambers, wherein the ion guide has: a first portion, in which gaps are formed between at least some of the electrode plates so that uncharged gas can escape from the ion guide volume, wherein the first portion is entirely located in the first pumping chamber; and a second portion, in which a sealing element is arranged between adjacent electrode plates to prevent neutral gas from escaping from the ion guide volume between adjacent electrode plates, the second portion extending at least from the separation wall to the second pumping chamber, wherein the method also includes the step of driving each two adjacent electrode plates with RF voltages of opposite polarity.

[0048] In a preferred embodiment, the method includes the step of driving every two adjacent electrode plates with an RF square wave signal or a superposition of RF square wave signals, wherein the method also includes the step of adjusting the RF frequency and voltage amplitude of the driving signal according to the type of ions to be guided by the ion guide.

[0049] In a preferred embodiment of the method, the ion guide is an ion guide according to one of the above embodiments.

[0050] Another aspect of the invention relates to a method of manufacturing an ion guide according to any of the above embodiments, wherein at least a second portion of the ion guide, including alternating electrode plates and sealing elements, is formed by 3D printing. Such 3D printing can be performed by alternating electrode plates (e.g., from a plastic material mixed with graphene, carbon nanotubes, carbon fibers, carbon black, graphite or metal, or a ceramic material mixed with a metal or metal oxide) and sealing elements, which can be made of similar materials but with a lower concentration of conductive components.

[0051] Another aspect of the invention relates to an ion guide suitable for use as the second part in an ion guide as described in one of the above embodiments. Such an ion guide can itself be manufactured and sold as an intermediate product and can be supplemented by additional electrode plates with gaps between the electrode plates to form the above first part of the complete ion guide. The ion guide described in this aspect of the invention comprises a plurality of electrode plates arranged perpendicular to the longitudinal axis, each electrode plate having an opening and arranged such that the longitudinal axis extends through its respective opening, wherein the openings together define an ion guide volume, wherein sealing elements are arranged between adjacent electrode plates to prevent neutral gas from escaping from the ion guide volume between adjacent electrode plates, wherein some or all of the sealing elements are composed of a resistivity of 10 2 Ohm·cm and 10 12 Ohm·cm, preferably between 3×10 5 Ohm·cm and 10 9 Ohm·cm, or have a resistivity between 10 4 Ohm and 10 14 Ohm, preferably between 3×10 7 Ohm and 10 10 Sheet resistivity between Ohms.

[0052] In a preferred embodiment, the intermediate resistivity material is a plastic material or a ceramic material comprising or mixed with conductive particles, in particular metal or graphite particles, or a ferrite-based material.

[0053] In a preferred embodiment, the intermediate resistivity material is a material suitable for 3D printing, and specifically a plastic material mixed with graphene, carbon nanotubes, carbon fibers, carbon black, graphite, or metal, or a ceramic material mixed with metal or metal oxide.

[0054] In a preferred embodiment, some or all of the sealing elements are coated with a coating suitable for discharging stray ions, at least on the surface facing the ion guide volume, so as to avoid electrostatic charging of the sealing elements caused by stray ions. In this context, the coating is preferably a metal film with a thickness of 30 to 1000 nm, or a slurry containing glass and metal oxide, wherein the thickness of the slurry is preferably 5 to 1000 μm.

[0055] In a preferred embodiment, at least some of the sealing elements are flush with the openings in one or both of their adjacent electrode plates, or are retracted from the openings in one or both of their adjacent electrode plates in a radially outward direction by less than 3 times, preferably less than 1.5 times, and most preferably less than 1.0 times, the distance between the corresponding adjacent electrode plates.

[0056] In a preferred embodiment, at least some of the electrode plates in the second part and the corresponding intermediate sealing elements are made of a material suitable for 3D printing, and in particular of a plastic material mixed with graphene, carbon nanotubes, carbon fibers, carbon black, graphite or metal, or a ceramic material mixed with metal or metal oxide. Another aspect of the invention relates to a method of manufacturing such an ion guide, wherein the ion guide is formed by 3D printing.

[0057] In a preferred embodiment, the first TWIN is followed by a third section in which a gap is formed between adjacent electrode plates to allow removal of neutral background gas by another pump, followed by a fourth sealing section that connects another two adjacent pumping chambers, and so on. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Figure 1 is a schematic diagram of an ion beam deposition system using a TWIN ion guide according to an embodiment of the present invention.

[0059] Figure 2 is a schematic cross-sectional view of a TWIN ion guide according to an embodiment of the present invention.

[0060] Figure 3 is a schematic cross-sectional view of a TWIN ion guide according to another embodiment of the present invention.

[0061] Figure 4 is a schematic cross-sectional view of a TWIN ion guide according to yet another embodiment of the present invention.

[0062] Figure 5 is a schematic cross-sectional view of a TWIN ion guide according to yet another embodiment of the present invention.

[0063] Figure 6 is a perspective view of a TWIN ion guide according to an embodiment of the present invention.

[0064] Figure 7 yes Figure 6 A perspective cross-sectional view of the TWIN ion guide.

[0065] Figure 8 yes Figure 6 and Figure 7 Cross-sectional view of the TWIN ion guide.

[0066] Fig. 9 An RF driving circuit for driving electrode plates of a TWIN ion guide according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0067] For the purpose of promoting an understanding of the principles of the present invention, reference will now be made to the preferred embodiments illustrated in the drawings and specific language will be used to describe the embodiments. It will be understood, however, that the scope of the invention is not thereby limited and such changes and further modifications in the illustrated apparatus and such further applications of the principles of the invention illustrated therein are deemed to be those which would normally occur now or in the future to those skilled in the art to which the present invention relates.

[0068] In the drawings described below, the same elements will be denoted by the same reference numerals, and description thereof will not be repeated.

[0069] Figure 1 The schematic diagram of ion beam deposition (IBD) system 10 is shown. IBD system 10 includes first pumping chamber 12 to fourth pumping chamber 18 separated by separation wall 20. Each of pumping chamber 12 to 18 is connected to corresponding vacuum pump 22. Although all vacuum pumps are represented by the same reference numeral 22, they can be of different types. On the left end of IBD system 10, electrospray ionization (ESI) device 24 is provided, in which molecules are ionized to produce molecular ions that will be used for final deposition on substrate 26 in the fourth chamber 18 located at the far right of this figure. ESI method is first described in Molecular Beams of Macroions (molecular ion beam) of Malcolm Dole, LLMack, RLMhines, RCMobley, D.Furgeson, MBAlice, JChemPhys 49p.2240 (1968). John B. Fenn won the Nobel Prize for this method, see John B. Fenn's Electrospray Wings for Molecular Elephants (Nobel Lecture), Angew Chem Int Ed 42 p. 3871 (2003). In the ESI device 24, the charged droplets of electrolyte are attracted by a very high voltage from a needle 28 operating at atmospheric pressure. In addition to the charged molecules to be deposited, each droplet also includes a large amount of unwanted solvent / carrier gas, which needs to be removed by a pump 22 connected to a series of pumping chambers 12 to 18. The ions and solvent / carrier gas are guided into the first pumping chamber 12 by a heated capillary 30.

[0070] The first pumping chamber 12 exhibits a pressure between 0.1 and 10 mbar. To form an ion beam, a combined ion funnel and tunnel device 32 according to an embodiment of the present invention is used, extending from the first pumping chamber 12 through a hole in the separating wall 20 into the second pumping chamber 14. The combined ion funnel and tunnel device 32 is referred to herein as a TWIN guide 32.

[0071] An electrode wire-based ion guide 36 is schematically shown extending from the second pumping chamber 14 through an opening in the separating wall 20 into the third pumping chamber 16. Wire-based ion guides may be referred to as "wire ion guides" (WIGs) for short, and are described in more detail in the co-pending patent application "Ion guide comprising electrode wires and ion beam deposition system", the contents of which are incorporated herein by reference. In this article, a portion of the WIG forms an aperture 34 through which neutral gas molecules can inadvertently pass from one chamber to another.

[0072] In the third pumping chamber 16, a quadrupole mass separator 38 is provided, which includes four rod electrodes 40. Also in the third pumping chamber 16, a first plate-based or "vane-based" ion guide (BIG) 42 is arranged, which is described in more detail in the co-pending patent application "Ion guide comprising electrode plates and ion beam deposition system". As shown in the schematic diagram, the first BIG 42 has a conical ion guide volume, the large diameter upstream end of which faces the quadrupole mass separator 38, and the small diameter downstream end faces the separation wall 20 between the third pumping chamber 16 and the fourth pumping chamber 18. In addition, at the downstream end of the first BIG 42, the electrode plates or "vanes" have a pointed tip, as further explained in the co-pending application "Ion guide comprising electrode plates and ion beam deposition system". Finally, a second BIG 42 is disposed in the fourth pumping chamber 18, having a conical ion guide volume with a small diameter upstream end facing the separation wall 20 between the third pumping chamber 16 and the fourth pumping chamber 18, and a large diameter downstream end facing the substrate 26. In addition, at the upstream end of the second BIG 42, the electrode plate or "vane" has a pointed tip.

[0073] Figures 2 to 5 A schematic cross-sectional view of a TWIN ion guide 32 is shown according to various embodiments of the present invention. Figures 2 to 5 are schematic, in that they only show the electrode plates 44, the sealing element 46 and the separating wall 20, but for the sake of clarity, any mounting structures are omitted, for example. Figures 2 to 5 are schematic, also because they are not drawn to scale, since the actual extension in the direction of the longitudinal axis 48 would be longer than shown in the figures. Figures 6 to 9 Certain embodiments are shown drawn to scale.

[0074] Figures 2 to 5 Each TWIN ion guide 32 shown is configured to guide an ion beam along an ion path and has a longitudinal axis 48 corresponding to the ion path. In addition, each TWIN ion guide 32 includes a plurality of electrode plates 44 arranged perpendicular to the longitudinal axis 48. Each electrode plate 44 includes an opening and is arranged such that the longitudinal axis 48 extends through its respective opening. The openings collectively define an ion guide volume 49. As shown in Figures 2 to 5As further shown in FIG. 1 , the TWIN ion guide 32 extends through the adjacent first and second pumping chambers (such as Figure 1 The pumping chambers 12 and 14 are shown separated by a separation wall 20.

[0075] Each TWIN ion guide 32 has a first portion 52 in which gaps are formed between adjacent electrode plates 44, allowing uncharged gas to escape from the ion guide volume 49. The first portion 52 is located entirely in the first pumping chamber 12, ie to the left of the separating wall 20.

[0076] Each TWIN ion guide 32 also has a second portion 54 in which a sealing element 46 is arranged between adjacent electrode plates 44. The sealing element 46 prevents neutral gas from escaping from the ion guide volume between adjacent electrode plates 44. In the embodiment shown, the sealing element 46 is formed by an annular disk that also serves as a spacer to adjust the distance between adjacent electrode plates 44. The dashed line 50 indicates the boundary between the first portion 52 and the second portion 54 of the TWIN ion guide 32. As shown in FIG. Figures 2 to 5 In each of the embodiments shown in FIG. 1 , the first portion 52 is completely located in the first pumping chamber 12 and the second portion 54 extends through the separation wall 20 into the second pumping chamber 14. In some embodiments, for example Figure 2 and Figure 3 In the embodiment of the present invention, the main part of the second portion 54 is also located in the first pumping chamber 12, and only a small part thereof (in principle, arbitrarily small) extends into the second pumping chamber 14. In other embodiments, for example Figure 4 and Figure 5 In some embodiments, approximately half of the second portion 54 extends into the second pumping chamber 14, and in other embodiments (such as Figures 6 to 8 In the embodiment shown), the main part or the whole of the second portion 54 may extend into the second pumping chamber 14. All these variations are covered by the aforementioned feature, according to which the second portion 54 extends "at least" from the separating wall 20 into the second pumping chamber 14. Figure 5 The embodiment of FIG. 1 depicts a particular order of diameters of the holes of the electrode plates. Figure 5 In the figure, there is no sharp change in hole diameter in the downstream direction from left to right. Starting from a constant hole diameter, it decreases slightly, enters a constant decreasing region, and finally tapers in a region of constant diameter. In particular, the tapering results in a smoother transition of the neutral gas beam entering the tube in the case of a constant hole diameter in the tunnel. Therefore, the ions also experience a smoother transition into the tunnel, resulting in fewer ion losses and higher current capacity.

[0077] The electrode plate 44 can be made of copper, molybdenum, tungsten, nickel or their compounds or alloys. The electrode plate 44 can also be made of stainless steel. The electrode plate can also be plated with silver or gold.

[0078] The thickness of the electrode plates 44 in the second portion 54 of the ion guide 32 may be 3 mm or less, preferably 1 mm or less, more preferably 0.3 mm or less and most preferably 0.1 mm or less. Also, the thickness is preferably 0.01 mm or more, preferably 0.02 mm or more and most preferably 0.03 mm or more. The average distance between adjacent electrode plates 44 in the second portion 54 is similar to the thickness, and in the embodiment shown, is substantially the same.

[0079] Furthermore, the ratio of the diameter of the opening in each electrode plate 44 to the distance to one of its adjacent electrode plates 44 may be between 2000 and 1.0, preferably between 2000 and 2.0. It should be noted that this ratio cannot be changed from Figures 2 to 5 identifiable in the drawings because the figures are not drawn to scale in this respect.

[0080] exist Figure 2 , Figure 4 and Figure 5 In the TWIN ion guide 32 of FIG. 5 , the sealing element 46 in the second portion 54 is flush with the opening in one or both of its adjacent electrode plates 44 . Figure 3 In the embodiment of the present invention, the sealing element 46 is retracted from the opening in one or both of its adjacent electrode plates 44 in a radially outward direction. When the sealing element 46 is flush with the opening in the adjacent electrode plate 44, the internal volume of the tunnel structure of the second portion 54 is minimized. In addition, the flush configuration is advantageous for the purpose of 3D printing described below. Although the present invention is not limited to the embodiment of the present invention, the present invention is not limited to the embodiment of the present invention. Figure 3 and Figure 5 Retracting the sealing element 46 in the manner shown will slightly increase the internal volume, but it results in a "rough" inner surface, which causes turbulence in the gas flow and can thereby help reduce gas conductivity and thereby reduce gas loading. A similar increase in turbulence can be produced by 3D printing when there is a slight smooth adjustment in the inner diameter between the spacer and the plate.

[0081] The natural choice of the sealing element 46 used as a spacer between adjacent electrode plates 44 is an insulating material so that the adjacent electrode plates 44 are insulated from each other, and the operation will be driven in opposite phases and therefore opposite polarities at any given point in time. However, in a flush configuration, or when the sealing element 46 is retracted only to a small extent (such as less than 3.0 times, less than 1.5 times, or even less than 1.0 times the distance between the corresponding adjacent electrode plates 44), there is a risk that the sealing element 46 will be hit by stray ions, which in the case of an insulating material will result in charging and therefore distortion of the electric field used to guide the ion beam, and thus a reduction in current capacity. With this in mind, according to various embodiments of the present invention, the sealing element 46 is made of a material with a resistivity of 10 2 Ohm·cm and 10 12 Ohm·cm, preferably between 3×10 5 Ohm·cm and 10 9 Ohm·cm. The intermediate resistivity material can be, for example, a plastic material or a ceramic material including or mixed with conductive particles, specifically metal or graphite particles, or a ferrite-based material. Particularly preferred are plastic materials mixed with graphene, carbon nanotubes, carbon fibers, carbon black, graphite or metals, or ceramic materials mixed with metals or metal oxides, because they allow 3D printing. Using an "intermediate resistivity material" having a resistivity selected from the above range, stray ions can be discharged while the resistivity is still high enough to prevent short circuits of adjacent electrode plates 44.

[0082] Instead of making the sealing element 46 completely of an intermediate resistivity material, it may be sufficient to provide a suitably high sheet resistivity at least on the surface facing the ion guide volume, preferably any surface facing the ion guide volume 49, for the purpose of excluding stray ions. Suitable sheet resistivity values ​​for this purpose are in the range of 10 4 Ohm and 10 14 Ohm, preferably between 3×10 7 Ohm and 10 10 In some embodiments, the bulk of the sealing element 46 may be an electrically insulating material, such as a ceramic material, wherein at least on the surface facing the ion guide volume, a coating suitable for discharging stray ions is provided, thereby avoiding electrostatic charging of the sealing element 46 caused by stray ions. Such a coating may include a metal film with a thickness of 30 to 1000 nm, or a slurry or "cement" containing glass and metal oxides, wherein the thickness of the slurry or cement may be 5 to 1000 μm.

[0083] As in Figures 2 to 5As further shown in the TWIN ion guide 32 of FIG. 5 , the diameter of the openings in the subset of the continuous electrode plates 44 of the first portion 52 decreases in a direction toward the center of the ion guide 32, thereby forming a "funnel structure". In this context, the term "funnel structure" indicates that the ion guide volume 49 is formed from the entrance of the TWIN ion guide 32 (at Figures 2 to 5 ) gradually tapers along the longitudinal axis 48 in the direction toward the second portion 54, thereby allowing a less concentrated or "blurred" ion beam to be received and focused before the ion beam is introduced into the second portion 54 forming an airtight "tunnel".

[0084] exist Figure 2 and Figure 3 In the embodiment of FIG. 5 , the funnel structure is formed entirely within the first portion 52, while the ion guide volume 49 in the entire second portion 54 is cylindrical. Figure 4 and Figure 5 In the embodiment of the present invention, the funnel structure is mainly formed in the first portion 52, but extends into the second portion 54 of the ion guide 32. It should be noted that in the first portion 52, the neutral gas mainly flows radially outward through the gaps between adjacent electrode plates 44, while in the second portion 54, this radial flow is blocked by the sealing element 46, so that the neutral gas flows only in the longitudinal direction, i.e., toward the second pumping chamber 14, which has a lower pressure than the first pumping chamber 12. In other words, the interface between the first portion 52 and the second portion 54 (which is at Figures 2 to 5 The direction of the gas flow changes at a point (highlighted by dashed line 50 in FIG. 1 ). The inventors have found that the best results in terms of gas loading and current capacity are obtained if this change in gas flow direction is not coincident with the point where the ion beam has reached its maximum concentration. Thus, while a funnel structure may be used in the first portion 52 and a cylindrical structure may be used in the second portion 54, as Figure 2 and Figure 3 As shown, however, in a preferred embodiment, the funnel structure actually extends into the second portion 54, as shown in FIG. Figure 4 and Figure 5 As shown, the ion beam is maximally focused only after the change in gas flow direction from radial to longitudinal occurs.

[0085] In addition, Figure 2 and Figure 3 In the embodiment shown, the funnel structure defines a "linear decrease" in the cross-section of the ion guide volume 49 along the axial axis 48 (thus, the ion guide volume 49 itself decreases quadratically). Figure 2 and Figure 3In the embodiment of the present invention, in the funnel-shaped structure area, the quotient of the difference between the diameters of the openings in adjacent electrode plates 44 divided by the distance between these adjacent electrode plates 44 is constant. However, the inventors have found that this is not the best structure in terms of high current capacity, and a smoother transition between the funnel structure part and the cylindrical part is actually advantageous. An advantageous structure in this regard is Figure 4 and Figure 5 , where the quotient of the difference between the diameters of the openings in adjacent electrode plates 44 divided by the distance between these adjacent electrode plates 44 gradually decreases in the downstream direction.

[0086] In addition, as in Figures 2 to 5 As shown in each of the embodiments of the present invention, the spacing between at least some adjacent electrode plates 44 in the first portion 52 is greater than the spacing between at least some adjacent electrode plates 44 in the second portion 54. The spacing between adjacent electrode plates 44 in the first portion 52 may be, for example, at least 1.5 times, preferably at least 3 times, greater than the spacing between adjacent electrode plates 44 in the second portion 54. That is, since the ion beam in the first portion 52 is less focused than the ion beam in the second portion 54 and the repulsive force that needs to be overcome by the RF field generated by the electrode plates 44 is smaller, ions can be safely confined even when the spacing between adjacent electrode plates 44 is larger.

[0087] Finally, it should be noted that the first portion 52 and the second portion 54 are seamlessly connected and in particular no DC lens is arranged between the first and second portions of the ion guide.

[0088] Figures 6 to 8 A TWIN ion guide 32 according to an embodiment of the invention is shown in more detail. Figure 6 shows a perspective view of a TWIN ion guide 32, Figure 7 A perspective cross-sectional view of a TWIN ion guide 32 is shown, and Figure 8 A cross-sectional view thereof is shown. As shown in these figures, each electrode plate 44 is formed by a relatively narrow annular element, which includes three radially extending mounting portions 56 connected to corresponding mounting structures 58. The radially extending mounting portions 56 are arranged at an angle of 120°. Every two adjacent electrode plates 44 are rotated 60° relative to each other. This allows the mounting portions 56 of the odd-numbered electrode plates 44 to be connected to three corresponding first common mounting structures 58, and allows the mounting portions 56 of the even-numbered electrode plates 44 to be connected to three corresponding second common mounting structures different from the three first common mounting structures 58. More generally, each electrode plate 44 can have N mounting portions 56 arranged at an angle of 360° / N, and adjacent electrode plates 44 can be rotated 180° / N relative to each other.

[0089] from Figure 8 The mounting structures 58 can be best understood. Each mounting structure 58 includes a rod 60 that feeds through an opening, the so-called eyelet, in the mounting portion 56 of the electrode plate 44. The distance between the actual plates 44 is controlled by the spacer elements 62 arranged between adjacent mounting portions 56 on the rod 60. Fine adjustment of the distance can be achieved by tightening the nut 64, thereby allowing the spacer 62 to be compressed or relaxed together, thereby fine-tuning the overall length of the odd or even electrode plate 44 stack. With this type of mounting, there are essentially two staggered electrode plate 44 stacks, namely the odd stack electrode plates 44 and the even stack electrode plates 44, and the precise extension of the stack in the longitudinal direction can be fine-tuned by operating the nut 64.

[0090] It should be noted that in operation, adjacent electrode plates 44 are driven with opposite phases and therefore opposite electrical polarities at any given point in time, but every other electrode plate 44 (i.e. all odd-numbered electrode plates 44 and all even-numbered electrode plates 44, respectively) are driven with the same polarity. In other words, only electrode plates driven with the same polarity share a common mounting structure 58. This has two important advantages. One advantage is that the mounting structure 58 can be used to connect all electrode plates 44 connected thereto to an RF voltage source (not shown). Another advantage is that only the mounting portions 56 of electrode plates 44 driven with the same polarity overlap each other, so that they do not contribute to the capacity of the TWIN ion guide 32 because they have the same voltage at any point in time. This situation would be different if the mounting portions 56 of adjacent, i.e. oppositely driven electrode plates 44 overlapped (rather than being offset by 60° (180° / N) relative to each other), where the overlap would actually have a serious contribution to the capacity. This is even more true since the relative dielectric constant of the spacer element 62 is typically 2 to 4, so that in principle the mounting portion 56 will have a considerable contribution to the overall capacitance.

[0091] It should be noted that Figures 6 to 8 One of the electrode plates 44 in the TWIN ion guide 32 is enlarged and thus forms a diaphragm, which can be used to close a larger opening in the separation wall 20, or substantially form a part of the separation wall 20 between adjacent pumping chambers.

[0092] Similar to Figures 2 to 5 The embodiment shown, Figures 6 to 8The TWIN ion guide 32 of FIG. 5 comprises a first portion 52 in which there are gaps between adjacent electrode plates 44, and a second portion 54 in which a sealing element 46 is arranged between adjacent electrode plates 44 to prevent the neutral gas from escaping from the ion guide volume 49 between adjacent electrode plates 44. In this embodiment, the boundary between the first portion 52 and the second portion 54 coincides with the boundary between the first pumping chamber 12 and the second pumping chamber 14. The ion guide volume in the first portion 52 is at its inlet side ( Figures 6 to 8 4 and 5. The left side in FIG. 4 has a cylindrical ion guide volume portion and a funnel structure portion which tapers towards the second portion 54. The ion guide volume 49 in the second portion 54 is cylindrical.

[0093] Figures 6 to 8 One mounting configuration shown allows very precise arrangement of the electrode plate 44 and the sealing element 46, the mounting itself being somewhat cumbersome. Manufacturing can be significantly simplified if at least the second part 54 of the TWIN ion guide 32 is made by 3D printing. For this purpose, the electrode plate 44 and the sealing element 46 in the second part 54 are both made of a material suitable for 3D printing, in particular a plastic material mixed with graphene, carbon nanotubes, carbon fibers, carbon black, graphite or metal, or a ceramic material mixed with metal or metal oxide.

[0094] Commercially available 3D printing equipment allows for adding layers of different materials on top of each other. This generally requires that the melting temperatures of the two materials be at least close to each other so that the lower layer does not melt or soften when the successive layer is placed on top of it. When forming the second portion 54 of the ion guide 32, the same or similar plastic material in which different concentrations of conductive particles are dispersed can be used to form the "electrode plate" 44 and the "sealing element" 46, respectively, where the "electrode plate" 44 and the "sealing element" 46 in this case correspond to areas of different resistivity within the same printed object.

[0095] Advantageously, the second portion 54 of the ion guide 32 is printed in an upright position, i.e., with the longitudinal axis 48 in the vertical direction, while continuously adding horizontal layers corresponding to the electrode plate 44 and the sealing element 46, respectively. In some embodiments, the electrode plate 44 and the sealing element 46 can be printed, including their respective openings. At current 3D printing accuracy, this is possible if the diameter of the opening is, for example, 1 mm or more, and the total length of the second portion of the ion guide is, for example, 100 mm. For smaller openings, the openings can be mechanically formed later using a high-precision drill. It is also possible to combine the printing procedure including the openings with the drilling procedure, wherein the openings in the printed electrode plate 44 and the sealing element 46 may not be large enough, but help guide the drill when drilling the subsequent openings. In some embodiments, only the electrode plate 44 and the sealing element 46 are formed by 3D printing, while other components, such as wiring for electrical connection of the electrode plate to the corresponding RF drive source, are added in a conventional manner. This makes the 3D printing process relatively easy and allows for fairly fast manufacturing. However, in other embodiments, additional external wiring can also be manufactured by 3D printing.

[0096] In operation, a high frequency AC voltage is applied to the electrode plate 44 at a frequency of about 0.05 to 20 MHz and an amplitude of about 0.1 to 100 V. For clarity of illustration, Figures 1 to 8 The corresponding high frequency drive source is omitted. The circuit diagram of a suitable drive source is given in Fig. 9 . The driving source includes a DC voltage source 104, four switches 100 and a control unit 106 for controlling the switching state of the switches 100. Between the switches 100 and the control unit 106, a potential separation element 102 is provided. An RF output voltage is provided at terminals 108 and 110. The control unit 106 controls the switch 100 to alternate between two switching states, namely a first switching state and an opposite second state, in which the upper left and lower right switches 100 are closed and the remaining switches 100 are disconnected, and in the second state, the lower left and upper right switches 100 are closed and the remaining switches 100 are disconnected. In the first switching state, the RF terminal 108 has a positive voltage and the RF terminal 110 has a negative voltage, while in the second switching state, the voltage is reversed. Therefore, by alternating between the first switching state and the second switching state, a square wave RF output voltage is provided at terminals 108 and 110 under the control of the control unit 106. In addition, under the control of the control unit 106, the output RF frequency can be freely adjusted.

[0097] Although preferred exemplary embodiments are shown and described in detail in the drawings and the foregoing description, these embodiments should be regarded as purely exemplary and not limiting of the present invention. In this regard, it should be noted that only preferred exemplary embodiments are shown and described, and all changes and modifications should be protected, which are currently or in the future within the scope of protection of the present invention defined in the claims.

[0098] 10. IBD System

[0099] 12. First pumping chamber

[0100] 14 Second pumping chamber

[0101] 16 Third Pumping Chamber

[0102] 18 Fourth Pumping Chamber

[0103] 20 Separation wall

[0104] 22 Vacuum pump

[0105] 24Electrospray ionization (ESI) equipment

[0106] 26 Substrate

[0107] 28 pins

[0108] 30 Heated capillary

[0109] 32 Combined Tunnel and Funnel (TWIN) ion guide

[0110] 34 holes

[0111] 36-wire based ion guide (WIG)

[0112] 38 Quadrupole mass separator

[0113] 40 rod electrode

[0114] 42-blade ion guide (BIG)

[0115] 44 Electrode Plate

[0116] 46 Sealing element

[0117] 48 longitudinal axis

[0118] 49 Ion guide volume

[0119] 50 The boundary between the first part and the second part of the ion guide 32

[0120] 52 The first part of the ion guide 32

[0121] 54 The second part of the ion guide 32

[0122] 56 Mounting portion of electrode plate 44

[0123] 58 Installation structure

[0124] 60 rod of mounting structure 58

[0125] 62 spacer for mounting structure 58

[0126] 64 Nut for mounting structure 58

[0127] 100 Switch

[0128] 102 Potential separation element

[0129] 104 DC voltage source

[0130] 106 Control Unit

[0131] 108 RF terminal

[0132] 110 RF terminal

Claims

1. An ion guide (32) for guiding an ion beam along an ion path, the ion guide (32) having a longitudinal axis (48) corresponding to the ion path, wherein the ion guide (32) comprises a plurality of electrode plates (44) arranged perpendicular to the longitudinal axis (48), each electrode plate (44) having an opening and arranged such that the longitudinal axis (48) extends through its respective opening, wherein the openings collectively define an ion guide volume (49), In operation, the electrode plates (44) are connected to an RF driving source for driving two adjacent electrode plates (44) with voltages of opposite polarities, characterized in that: The ion guide (32) extends or is configured to extend through a separation wall (20) separating adjacent first pumping chambers (12) and second pumping chambers (14), The ion guide (32) has: a first portion (52) in which gaps are formed between at least some of the electrode plates (44) to allow uncharged gas to escape from the ion guide volume (49), wherein the first portion (52) is entirely within the first pumping chamber (12), and a second portion (54) within the first pumping chamber (12). In a second portion (54), a sealing element (46) is arranged between adjacent electrode plates (44) to prevent neutral gas from escaping from the ion guide volume (49) between adjacent electrode plates (44), and the second portion (54) extends at least from the separating wall (20) into the second pumping chamber (14).

2. The ion guide (32) of claim 1, wherein some or all of the sealing elements (46) are made of a material having a resistivity between 10 2 Ohm·cm and 10 12 Ohm·cm, or has a resistivity between 10 and 10 on the surface facing the ion guide volume (49). 4 Ohm and 10 14 Sheet resistivity between Ohms.

3. The ion guide (32) of claim 1 or 2, wherein some or all of the sealing elements (46) are made of a material having a resistivity of 3×10 5 Ohm·cm and 10 9 Ohm·cm, or has a resistivity between 3×10 7 Ohm and 10 10 Sheet resistivity between Ohms.

4. The ion guide (32) of claim 2, wherein the intermediate resistivity material is a plastic material or a ceramic material including or mixed with conductive particles, or a ferrite based material.

5. The ion guide (32) of claim 2, wherein the intermediate resistivity material is a material suitable for 3D printing.

6. The ion guide (32) of claim 2, wherein the intermediate resistivity material is a plastic material mixed with graphene, carbon nanotubes, carbon fibers, carbon black, graphite, or metal, or a ceramic material mixed with metal or metal oxide.

7. An ion guide (32) as claimed in claim 1 or 2, wherein some or all of the sealing elements (46) are coated with a coating suitable for discharging the charge of stray ions, at least on the surface facing the ion guide volume (49), so as to avoid electrostatic charging of the sealing elements (46) caused by stray ions.

8. The ion guide (32) of claim 7, wherein the coating is a metal film having a thickness of 30 to 1000 nm, or a slurry containing glass and metal oxide.

9. The ion guide (32) of claim 8, wherein the slurry has a thickness of 5 to 1000 μm.

10. An ion guide (32) as described in claim 2, wherein at least some of the sealing elements (46) are flush with the openings in one or both of their adjacent electrode plates (44), or are retracted from the openings in one or both of their adjacent electrode plates in a radially outward direction by less than 3 times the distance between the corresponding adjacent electrode plates (44).

11. The ion guide (32) of claim 2, wherein at least some of the sealing elements (46) are retracted in a radially outward direction from openings in one or both of their adjacent electrode plates by less than 1.5 times the distance between corresponding adjacent electrode plates (44).

12. The ion guide (32) of claim 2, wherein at least some of the sealing elements (46) are retracted in a radially outward direction from openings in one or both of their adjacent electrode plates by less than 1.0 times the distance between corresponding adjacent electrode plates (44).

13. The ion guide (32) of claim 1 or 2, wherein at least some of the electrode plates (44) located in the second portion (54) are made of a material suitable for 3D printing.

14. The ion guide (32) of claim 13, wherein at least some of the electrode plates (44) located in the second portion (54) are made of a plastic material mixed with graphene, carbon nanotubes, carbon fibers, carbon black, graphite or metal, or a ceramic material mixed with metal or metal oxide.

15. The ion guide (32) of claim 1 or 2, wherein the sealing element (46) is formed by an annular disk, wherein the annular disk is used as a spacer to adjust the distance between adjacent electrode plates (44).

16. An ion guide (32) as claimed in claim 1 or 2, wherein in one of the first part (52) and the second part (54), the diameter of the openings in at least a subset of the continuous electrode plates (44) decreases in the downstream direction of the ion guide (32), thereby forming a funnel structure.

17. An ion guide (32) as claimed in claim 1 or 2, wherein in the first portion (52), the diameter of the openings in at least a subset of consecutive electrode plates (44) decreases in a downstream direction of the ion guide (32), thereby forming a funnel structure.

18. An ion guide (32) as described in claim 16, wherein in at least a portion of the funnel structure, a quotient of a difference between diameters of openings in adjacent electrode plates (44) divided by a distance between the adjacent electrode plates (44) gradually decreases in the downstream direction of the ion guide (32).

19. The ion guide (32) of claim 16, wherein the funnel structure is formed primarily in the first portion (52) but extends into the second portion (54) of the ion guide (32).

20. The ion guide (32) of claim 1 or 2, wherein no DC lens is arranged between the first portion (52) and the second portion (54) of the ion guide (32).

21. The ion guide (32) of claim 1 or 2, wherein the spacing between at least some adjacent electrode plates (44) in the first portion (52) is at least 1.5 times greater than the spacing between at least some adjacent electrode plates (44) in the second portion (54).

22. The ion guide (32) of claim 21, wherein the spacing between at least some adjacent electrode plates (44) in the first portion (52) is at least 3 times greater than the spacing between at least some adjacent electrode plates (44) in the second portion (54).

23. The ion guide (32) of claim 1 or 2, wherein in a transition region between the first portion (52) and the second portion (54), the spacing between adjacent electrode plates (44) is uniform or varies by at least less than 15%.

24. The ion guide (32) of claim 23, wherein the transition region comprises at least three electrode plates (44) within each of the first portion (52) and the second portion (54).

25. An ion guide (32) as described in claim 1 or 2, wherein the electrode plate (44) is formed by an annular element, which includes two or more radially extending mounting portions (56) connected to corresponding mounting structures (58), wherein the mounting portions (56) of the odd-numbered electrode plates (44) are connected to one or more first common mounting structures (58), and the mounting portions (56) of the even-numbered electrode plates (44) are connected to one or more second common mounting structures (58) different from the one or more first common mounting structures (58).

26. The ion guide (32) of claim 25, wherein the mounting structure (58) is further configured to apply a drive voltage to the electrode plate (44).

27. The ion guide (32) of claim 1 or 2, wherein the electrode plate (44) is made of copper, molybdenum, tungsten, nickel or compounds or alloys thereof, or is made of stainless steel, and / or wherein the electrode plate (44) is plated with silver or gold.

28. The ion guide (32) of claim 1 or 2, wherein a thickness of the electrode plate (44) in the second portion (54) of the ion guide (32) is 3 mm or less and 0.01 mm or more.

29. The ion guide (32) of claim 28, wherein a thickness of the electrode plate (44) in the second portion (54) of the ion guide (32) is 0.3 mm or less and 0.02 mm or more.

30. The ion guide (32) of claim 1 or 2, wherein an average distance between adjacent electrode plates (44) in the second portion (54) of the ion guide (32) is 3 mm or less and 0.01 mm or more.

31. The ion guide (32) of claim 30, wherein an average distance between adjacent electrode plates (44) in the second portion (54) of the ion guide (32) is 0.3 mm or less and 0.02 mm or more.

32. An ion guide (32) as claimed in claim 1 or 2, wherein for at least 10% of the electrode plates (44), the ratio of the diameter of the opening in each electrode plate (44) to the distance to one of its adjacent electrode plates (44) is between 2000 and 1.

0.

33. An ion guide (32) as claimed in claim 32, wherein for at least 50% of the electrode plates (44), the ratio of the diameter of the opening in each electrode plate (44) to the distance to one of its adjacent electrode plates (44) is between 2000 and 2.

0.

34. The ion guide (32) of claim 1 or 2, wherein the electrode plates (44) are connected to an RF driving source, and the RF driving source is configured to drive two adjacent electrode plates (44) with voltages of opposite polarities and freely adjustable radio frequencies.

35. The ion guide (32) of claim 34, wherein the RF drive source is configured to drive the electrode plate (44) with an RF square wave signal.

36. The ion guide (32) of claim 34, wherein the RF drive source is configured to drive the electrode plate (44) with a superposition of RF square wave signals.

37. An ion guide (32) as described in claim 2, wherein a DC potential gradient is formed along the length of at least a portion of the second portion (54) of the ion guide by means of a DC current passing through the corresponding electrode plate (44) and an intermediate resistivity sealing element arranged between the corresponding electrode plates (44) through the sheet resistivity of the sealing element or through an external resistor arranged between adjacent electrode plates (44).

38. An ion guide (32) as described in claim 1 or 2, wherein the ion guide (32) is part of an ion beam deposition system (10), in which the ion beam is guided through a plurality of pumping chambers (12, 14, 16, 18) of reduced pressure, wherein adjacent pumping chambers (12, 14, 16, 18) are separated by a separation wall (20), the separation wall (20) having a hole for the ion beam to pass through.

39. An ion beam deposition system (10) comprising at least one ion guide (32) as claimed in claim 1 or 2.

40. A method for guiding an ion beam along an ion path using an ion guide (32) according to claim 1 or 2, the ion guide having a longitudinal axis (48) corresponding to the ion path, wherein the ion guide (32) comprises a plurality of electrode plates (44) arranged perpendicular to the longitudinal axis (48), each electrode plate (44) having an opening and arranged such that the longitudinal axis (48) extends through its respective opening, wherein the openings collectively define an ion guide volume (49), The ion guide (32) extends through a separation wall (20) separating adjacent first pumping chamber (12) and second pumping chamber (14), wherein: The ion guide (32) has: a first portion (52) in which gaps are formed between at least some of the electrode plates (44) so ​​that uncharged gas can escape from the ion guide volume (49), wherein the first portion (52) is located entirely in the first pumping chamber (12), and a second portion (54) in which sealing elements (46) are arranged between adjacent electrode plates (44) to prevent neutral gas from escaping from the ion guide volume (49) between adjacent electrode plates (44), wherein the second portion (54) extends at least from the separating wall (20) into the second pumping chamber (14), The method further comprises the step of driving every two adjacent electrode plates (44) with RF voltages having opposite polarities.

41. A method as claimed in claim 40, comprising the step of driving every two adjacent electrode plates (44) with an RF square wave signal, wherein the method further comprises the step of adjusting the RF frequency and voltage amplitude of the driving signal according to the type of ions to be guided by the ion guide (32).

42. A method as claimed in claim 41, comprising the step of driving every two adjacent electrode plates (44) with the superposition of RF square wave signals, wherein the method further comprises the step of adjusting the RF frequency and voltage amplitude of the driving signal according to the type of ions to be guided by the ion guide (32).

43. A method of manufacturing the ion guide (32) of claim 5, wherein at least the second portion (54) of the ion guide (32) is formed by 3D printing, the second portion (54) comprising alternating electrode plates (44) and sealing elements (46).

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