EP3021351A1 - Multiplicateur d'electrons secondaire et son procede de fabrication - Google Patents

Multiplicateur d'electrons secondaire et son procede de fabrication Download PDF

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Publication number
EP3021351A1
EP3021351A1 EP15194327.1A EP15194327A EP3021351A1 EP 3021351 A1 EP3021351 A1 EP 3021351A1 EP 15194327 A EP15194327 A EP 15194327A EP 3021351 A1 EP3021351 A1 EP 3021351A1
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EP
European Patent Office
Prior art keywords
dynodes
optionally
secondary electron
detector
electron multiplier
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Application number
EP15194327.1A
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German (de)
English (en)
Inventor
Maria Reinhardt-Szyba
Jörg Müller
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Bayer AG
Krohne Messtechnik GmbH and Co KG
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Krohne Messtechnik GmbH and Co KG
Bayer Technology Services GmbH
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Application filed by Krohne Messtechnik GmbH and Co KG, Bayer Technology Services GmbH filed Critical Krohne Messtechnik GmbH and Co KG
Publication of EP3021351A1 publication Critical patent/EP3021351A1/fr
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J43/00—Secondary-emission tubes; Electron-multiplier tubes
    • H01J43/04—Electron multipliers
    • H01J43/06—Electrode arrangements
    • H01J43/18—Electrode arrangements using essentially more than one dynode
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J43/00—Secondary-emission tubes; Electron-multiplier tubes
    • H01J43/04—Electron multipliers
    • H01J43/28—Vessels, e.g. wall of the tube; Windows; Screens; Suppressing undesired discharges or currents

Definitions

  • the present invention relates to a secondary electron multiplier especially for use in microsystems with improved manufacturability.
  • the present invention further relates to a method of manufacturing a photomultiplier.
  • Secondary electron multipliers with discrete dynodes serve to multiply low photon, ion and electron currents.
  • the multiplication of low primary electron currents by a photomultiplier is used in electron tubes, for example, in a photomultiplier for amplification.
  • a photomultiplier typically includes a plurality of dynodes, that is, a plurality of individual electrodes from an overall array of discrete electrodes, often in the millimeter range, such as in a range of 5mm or more.
  • each end of a source for the photon, ion or electron flow or a detector for detecting the amplified photon, ion and electron flow may be provided, wherein the source and the detector are further connected to a per se known voltage divider to the individual dynodes can create a defined voltage.
  • focusing devices can be provided in order to allow a suitable alignment of the electrodes, in particular the anode and the cathode, for the purpose of a desired focusing of the charge carrier beam.
  • an accelerator voltage is usually applied across the entire series of dynodes.
  • the voltage can drop between the outermost dynodes and electrons, for example, can be accelerated from dynode to dynode. If an electron strikes the surface of a dynode, further electrons are emitted and the current is amplified.
  • the individual discrete dynodes thus form the amplifier stages of the secondary electron multiplier.
  • the primary charge carriers strike the first discrete dynode and generate more secondary electrons than primary charge carriers are hit on this dynode.
  • ⁇ secondary electrons / primary charge carrier> 1.
  • Normally values of ⁇ 3 to 10 are achieved in the case of secondary electron multipliers, but the secondary electron coefficient here depends not only on the material of the dynodes used but also, for example, on the energy of the primary charge carrier and thus on the voltage between the dynodes.
  • the gain of the photomultiplier is therefore ⁇ n at n dynodes.
  • a secondary electron multiplier comprising an electrically insulating substrate on which a plurality of discrete dynodes and optionally at least one focusing electrode and optionally a detector are arranged. Furthermore, a line structure for applying defined different electrical potentials to the dynodes is provided. A volume positioned spatially between the dynodes and, if appropriate, a volume positioned between at least one dynode and the at least one focusing electrode and optionally a volume positioned between at least one dynode and the detector can be subjected to a vacuum.
  • the secondary electron multiplier is characterized in that at least the dynodes and, if appropriate, the detector and possibly the at least one focusing electrode have a spatial extent in a range of ⁇ 50 ⁇ m to ⁇ 1000 ⁇ m, in particular 100 ⁇ m to ⁇ 750 ⁇ m.
  • secondary electron multiplier In a previously described secondary electron multiplier, it is thus provided in particular not to produce the active structures, in particular the dynodes and, if appropriate, the detector and the focusing electrodes, as is customary in the prior art, in the millimeter range, but rather in a range of ⁇ 1000 ⁇ m and thereby produced by microsystem technology.
  • a prescribed In this way, secondary electron multipliers allow a significantly simplified manufacturability compared to the systems of the prior art, in particular without an additional adjustment step, accompanied by a large variability in shaping and a high amplification potential using microsystem processes for the production of microsystem components and thereby an improved integration into existing systems.
  • a "plurality of dynodes” may mean that at least two and, in principle, any number greater than two may be present on dynodes.
  • discrete dynodes may mean, in a manner understood by those skilled in the art, that the intended dynodes are spatially separated and thus do not touch, so that the discrete dynodes may have a different electrical potential.
  • microsystem components may in particular be understood to mean components which have a maximum extent and thus a size in the length and / or the width and, if appropriate, the height which is in a range of micrometers, in particular 50 ⁇ m to less or equal to 1000 ⁇ m, lies.
  • microsystem components may have a maximum extent or size in the above-described region, in particular in each of the provided planes or three-dimensionally.
  • the length may mean the longest extent of the corresponding structure, whereas the width may be the corresponding transversely extending extent.
  • the height may in particular mean the thickness of the structure, for instance on the substrate.
  • the size of the corresponding structures can be determined in a manner which is readily understood by the person skilled in the art by optical methods, for example by means of scanning electron microscopy.
  • a "microsystem method” is understood to mean a method by which components in the above-described size range can be defined and reproducibly produced or produced.
  • a prescribed secondary electron multiplier thus initially comprises an electrically insulating substrate on which a plurality of discrete dynodes and optionally at least one focusing electrode and optionally a detector are arranged.
  • an electrically insulating substrate can be understood as meaning a substrate whose electrical resistance is sufficiently high so as to allow a desired operation of the secondary electron multiplier and, in particular, to allow the presence of a respective different electrical potential of the dynodes separated from each other.
  • the intended dynodes serve in a conventional manner as the actual gain components of the secondary electron multiplier by these, when primary charge carriers or primary electrons meet in the first direction discrete in the gain direction dynode generate more secondary electrons are taken as primary charge carriers to this dynode, wherein the increased number of electrodes are accelerated toward the next dynode in the gain direction by the respective electric potential of the dynodes so as to cause a boosting effect.
  • This amplification effect is fundamentally in accordance with the basically known operating principle of a secondary electron multiplier.
  • the invention will be described in particular below by amplifying an electron current or electron beam.
  • photon or ion currents can be amplified, for example, if a fundamentally known conversion electrode or a substrate with a photoelectron emitter layer is provided at the entrance of the secondary electron multiplier.
  • a conversion electrode or conversion dynode can generate electrons from ions in a manner known per se.
  • the electrode may comprise an alkali metal or an alkali metal alloy as a coating, whereby electrons may be released upon the impact of an ion beam.
  • a photoelectron emitter layer may be such a layer that releases electrons upon impact of photons or light.
  • a layer may include, for example, sub-oxides of cesium, alkali metals or antimony.
  • the conversion electrode as well as the photoelectron emitter layer can also be arranged approximately on the substrate and manufactured in terms of process technology uniformly with the dynodes, for example by the same methods, whereby a fully integrated photon electron multiplier can be realized.
  • At least one, possibly a plurality, may be provided on so-called focusing electrodes.
  • These electrodes are arranged in particular in the beam path of the electrons at the beginning of the photomultiplier.
  • the electrons first strike or pass through the focusing electrodes as the charge carrier current or the charge carrier beam to be amplified.
  • These electrodes serve to align the electron beam in a particularly defined manner and to direct it to the first dynode. As a result, a particularly defined electron flow and thus a particularly advantageous amplification can be realized.
  • the last dynode in the direction of amplification can be followed by a further electrode serving as a detector, to which the amplified electron current or Carrier current meets after continuous amplification.
  • the detector can also be arranged on the electrically insulating substrate and configured as a microsystem component in the above-described size range and be produced with the same method as the dynodes.
  • the dynodes are provided in a number from greater than or equal to 2 to less than or equal to 20, preferably greater than or equal to 5 to less than or equal to 15, greater than or equal to 5 to less than or equal to 10, the above values not being limiting are. Due to the above-described number of dynodes, however, a high gain can already be combined with a very compact design. In principle, the number of dynodes is to be selected, for example, as a function of the desired amplification factor and, for example, as a function of the pressure or vacuum that can be generated between the dynodes.
  • At least one spatially between the dynodes and optionally between at least one dynode, so in particular the gain first direction dynode, and the at least one focusing electrode, or in the presence of a plurality of focusing electrodes preferably also between the respective focusing electrodes, and optionally between at least one dynode, so in particular the last in the direction of amplification dynode, and the detector positioned volume with a vacuum or a reduced pressure can be acted upon.
  • the dynodes can be arranged in a chamber which can be acted upon with a reduced pressure.
  • such a chamber can be understood to mean, in particular, a chamber which can be closed in a pressure-tight or vacuum-tight manner at least temporarily for using the secondary electron multiplier and which, in particular, can have a connection for connecting a vacuum pump.
  • a vacuum may also be understood as meaning, in particular, a reduced pressure with respect to the ambient atmosphere (1 atm; 1.01325 bar), which, for example but not restricting, in a range of greater than or equal to 10 -3 mbar to less than or equal to 10 -2 mbar , or may be over it.
  • a gain can be the more effective, the lower the pressure.
  • the pressure can basically be selected application-related, for example, depending on the number of dynodes, the desired gain and the spacing of the dynodes.
  • the chamber which can be acted upon with a reduced pressure can be designed in such a way that at least the dynodes and optionally the at least one focusing electrode and optionally the detector are completely or at least partially and the space located between the dynodes and used as the electron radiation space is arranged completely in the chamber that at least the active surfaces of the dynodes and the intervening space can be acted upon by a vacuum.
  • a conversion electrode and / or a photoelectron emitter layer can also be arranged in the chamber, if present.
  • the substrate which serves as a support for the electrodes can be arranged completely in the chamber, or the substrate can form a part of the chamber wall.
  • a low pressure or a vacuum may therefore be advantageous because the gain is reduced by collisions of the charge carriers with neutral gas particles, which are located between the dynodes.
  • the gain decreases with increasing ambient pressure, so that operating under a vacuum can enable a particularly advantageous amplification potential.
  • it can be prevented by the formation of a vacuum, or at least reduce the risk that, by forming plasmas to electrical breakdowns in the operation of the Sekundärelektonenvervielfachers.
  • the shape of the dynodes can furthermore basically be freely selectable. Practically, however, at least the active surface of the dynodes should be designed or formed and / or aligned such that the irradiated electrons can be reflected such that they strike the dynode following in the radiation direction or in the amplification direction. For example, it may be preferable for the dynodes to have a curved, somewhat banana-like shape. However, it will be understood by those skilled in the art that the electrons move through the photomultiplier, in particular through acceleration caused by the corresponding potential of the dynodes.
  • the dynodes may be positioned in an array that corresponds to one or more, particularly parallel, rows. Such an arrangement can be simple and very compact. Basically, the geometry of the dynodes and their arrangement with each other or each other, however, freely selectable, as far as a suitable radiation path of the electrons can be formed.
  • the secondary electron multiplier according to the invention may further comprise a line structure, which includes the dynodes and optionally the at least one focusing electrode supplied electrical voltage or brings them to a desired electrical potential.
  • a line structure which includes the dynodes and optionally the at least one focusing electrode supplied electrical voltage or brings them to a desired electrical potential.
  • voltage dividers for example in the form of, for example, thin-film resistors
  • electrical resistors may also be provided in the line structure, as is fundamentally known functionally for secondary electron multipliers.
  • the line structure can be, for example, by approximately metallic Conductor tracks are formed, which are connected to the corresponding dynodes or connected to these.
  • the shape and size of the line structure can be adapted to the corresponding microstructure components.
  • the line structure may also be applied to the substrate, which may allow a particularly simple manufacturability.
  • the conductor tracks of the line structure may, for example, have a thickness in a range of ⁇ 0.1 to ⁇ 2 ⁇ m, for example of 1 ⁇ m, and / or a width in a range of ⁇ 1 ⁇ m to ⁇ 100 ⁇ m.
  • a corresponding voltage supply can advantageously take place via a discrete voltage supply system, as is basically known.
  • shields can be provided which can be arranged between the line structures which can bring the dynodes to the corresponding electrical potential.
  • Such shields may also be referred to as floating mechanical barriers made in the same way as and simultaneously with the dynodes.
  • the shields are preferably narrow, beyond the width of the leads "walls” that prevent electrical breakdown between the leads due to their mechanical barrier effect for ions and electrons. They are not electrically connected, so floating. The distance should be smaller than the free path between the dynodes depending on the ambient pressure.
  • a source for a photon, ion or electron flow may be provided, such as a mass spectrometer or other source for the above-described charge carrier beam to be amplified.
  • the charge carrier beam to be amplified may be directed onto the secondary electrode multiplier such that it impinges on the first dynode in amplification direction or, if appropriate, on the first focusing electrode or photoelectron emitter layer or conversion electrode in the beam direction.
  • the above-described source for the photon, ion or electron current and the detector can likewise be connected to the line structure, so that a voltage applied between source and detector can be generated and a current flowing through the detector can be detected which can increase in accordance with the amplification factor of the photomultiplier.
  • the secondary electron multiplier is further provided that at least the dynodes and, if appropriate, the at least one focusing electrode, the line structure and in particular when the detector is applied to the substrate and the detector are designed as microsystem components and are applied to the substrate by a microsystem method.
  • the secondary electron multiplier is at least partially produced by a microsystem method or by the methods of microsystem technology.
  • Exemplary and particularly preferred production methods of microsystem technology are for the production of the lithography process by geometry defining anisotropic reactive ion etching (DRIE etching) for silicon (Bosch process) and for the production of metallic microstructures the LIGA process, for coating and production of interconnects, for example, deposition methods, such as such as PVD (Physical Vapor Deposition), CVD (Chemical Vapor Deposition), sputtering and vapor deposition. Exemplary corresponding methods will be described in detail with reference to the method.
  • DRIE etching anisotropic reactive ion etching
  • PVD Physical Vapor Deposition
  • CVD Chemical Vapor Deposition
  • sputtering vapor deposition
  • a sandwich structure may be formed, which is composed of several layers, wherein the dynodes and optionally the other microsystem components, such as at least one of the focusing electrode or focusing electrodes, the detector and the line structure, for example, in the middle of the sandwich structure are arranged.
  • a structure may in no limited way have the following layer sequences: glass-silicon-glass or about insulator-metal-glass.
  • the dynodes can be surrounded, for example, at low pressure by a hermetically sealing ring of silicon or metal.
  • the contact can then be advantageously carried out by means of metallic feedthroughs through the insulating bottom or top substrates by here, for example, pressure-tight closed cable bushings are provided.
  • a prescribed photomultiplier has significant advantages over the conventional prior art multipliers.
  • a prescribed secondary electron multiplier can be used particularly advantageously in microsystem technology or in microsystems.
  • yours such secondary electron multiplier be integrated directly into such systems.
  • integration in a micro-mass spectrometer for example in a so-called PIMMS system (planar integrated miniaturized mass spectrometer) may be advantageous.
  • PIMMS system planar integrated miniaturized mass spectrometer
  • the entire system can be produced simultaneously or in a batch process, so that a cost-effective and simple production of such a microsystem can result.
  • such a secondary electron multiplier can usually be easily incorporated into an existing or to be formed peripherals, such as resistors for a potential distribution and optics, or dynodes.
  • the entire unit comprising secondary electron multipliers and further systems, for example mass spectrometers, can then be arranged preferably in a vacuum chamber.
  • the measuring units can be arranged in the vacuum chamber, whereas evaluation units, for example, can be arranged outside the chamber.
  • the frequency of collisions between neutral particles located between the dynodes and charge carriers to be amplified is further determined, apart from the gas pressure, as described in detail above, by the ratio of the mean free path and the total travel distance of the charge carriers.
  • a vacuum as described above, also due to the small dimensions of the secondary electron multiplier as microsystem component or in particular the dynodes and concomitantly due to the small distance between the dynodes, as described above in a range of ⁇ 10 ⁇ m to ⁇ 500 ⁇ m, For example, from ⁇ 150 ⁇ m to ⁇ 300 ⁇ m, for example, be of about 250 ⁇ m or up to 20 ⁇ m, a particularly high effectiveness of reinforcement may be possible.
  • the above-described ranges may relate in particular to use in a pressure range from 10 -4 Pa to 1 Pa or from 10 -6 mbar to 0.01 mbar.
  • the secondary electron multiplier is configured by a method of micro-system technology, this problem does not occur in a prescribed secondary electron multiplier. Rather, the above-described photomultiplier can be formed directly by the manufacturing method, such as by an etching method or by a deposition method, in the desired shape and geometry and thus in a defined orientation of the components to each other, so that an adjustment need not be made. As a result, the method step of the adjustment, which is often complex in the prior art, can be achieved completely eliminated, which can make a manufacturing process particularly simple and inexpensive.
  • a particularly good adaptability can be made possible by a largely arbitrary arrangement of the dynodes due to the customizable manufacturability of the structures to be produced, in particular the dynodes and the power supply.
  • integrated multipliers such as photon multipliers
  • implementation of integrated multipliers can be carried out in the batch process, or integration with other microanalysis systems may be possible in a common manufacturing process.
  • the close spacing between the dynodes also allows the vacuum requirements to be significantly reduced, so that under comparable conditions, the vacuum may be sufficient to provide a comparatively lower vacuum compared to prior art secondary electron multipliers in the millimeter range.
  • pressures in a range of 0.1 mbar, about 10 -3 mbar or even more, ie a comparatively low vacuum, may already be sufficient, whereas in the prior art pressures in a range of, for example, 10 -6 mbar are often required.
  • a vacuum lower by powers of ten may be sufficient.
  • a prior art secondary electron splitter since conventional discrete-mode secondary photomultipliers, also called discrete SEVs, have dynodes several millimeters in size, also in the millimeter range, in a range of 3mm or greater have and thus have a corresponding high space required.
  • the prior art photomultiplier tubes have relatively high vacuum requirements because of the high spacing between the individual dynodes.
  • the prior art discrete photomultipliers are not suitable for direct integration with other microsystem components, such as Micro mass spectrometers, suitable. This is true even if they do not allow a reduced space requirement while maintaining the reinforcing properties in the rule.
  • the secondary electron multiplier also allows a manufacturing method with a particularly simple supply of dynodes, for example, with the different potentials by thin film resistors, since these resistors can be connected directly to the dynodes. Furthermore, the line structure can be produced in a method together with the other structures, so that a particularly simple manufacturability can be made possible.
  • the above-described secondary electron multiplier allows in a simple manner a particularly simple and cost-effective manufacturability with simultaneously high amplification power.
  • the dynodes and, if appropriate, the at least one focusing electrode and optionally the detector can have a maximum extent which lies in a range of ⁇ 50 ⁇ m to ⁇ 750 ⁇ m, for example ⁇ 250 ⁇ m to ⁇ 500 ⁇ m.
  • a particularly compact training can be realized along with a good reinforcement.
  • a particularly good adaptability to given microsystem components or a particularly good implementability in microsystems can take place and thus particularly compact components having such a secondary electron multiplier can be produced.
  • the maximum extent should be chosen in particular in order to still ensure a sufficient boosting force.
  • the substrate may comprise a material which is selected from the group consisting of glass, ceramic, silicon oxide, in particular silicon dioxide, and sapphire.
  • the aforementioned materials can be used in a simple way in microsystems technology.
  • these materials furthermore have an insulation quality which allows advantageous operation of the secondary electron multiplier.
  • the substrates may, for example, have a thickness which is in a range of ⁇ 300 ⁇ m to ⁇ 1000 ⁇ m, for example of ⁇ 400 ⁇ m to ⁇ 500 ⁇ m.
  • At least the dynodes and optionally the at least one focusing electrode and optionally the detector may comprise a material, in particular be formed from this material, which is selected from the group consisting of doped silicon or metals, such as gold, copper, nickel or silver.
  • dopants for the silicon include in particular boron, nitrogen, phosphorus, aluminum, indium, arsenic and antimony. Suitable doping concentrations further include, but are not limited to, the range of 10 16 to 10 21 cm -3 .
  • a doping with respect to the selection of the dopant or the doping concentration is carried out in particular such that the selection is adapted to the desired efficiency of the secondary electron multiplier, or that a sufficient electrical conductivity of the structures for a desired operation of the photomultiplier is given.
  • the material in particular in so far as the dynodes are designed with this, may also be coated with a material which is not electrically conductive and which increases the secondary electron coefficient, such as aluminum oxide (Al 2 O 3 ) or silicon dioxide (SiO 2 ), wherein the Coating, for example, can be carried out by methods known per se, such as deposition methods known per se, for example physical vapor deposition (PVD) or chemical vapor deposition (CVD).
  • PVD physical vapor deposition
  • CVD chemical vapor deposition
  • a dynode may be particularly preferably made of silicon, wherein a coating of silicon dioxide can be configured by oxidation.
  • a high secondary electron coefficient can be made possible in particular by the aforementioned coating of the dynodes, which enables a particularly effective amplification.
  • the secondary electron multiplier may have a layer structure in which two substrates are provided, between which at least the dynodes and optionally the detector and optionally the at least one focusing electrode and optionally at least partially the line structure are arranged.
  • a structure can thus form, in particular, a so-called sandwich structure, in which the microsystem components, in particular the dynodes and optionally the at least one focusing electrode and optionally the detector are arranged.
  • such a structure may comprise, for example, two glass substrates, between which the microsystem components, in particular the dynodes and, if appropriate, the at least one focusing electrode and optionally the detector, are formed approximately from doped silicon.
  • a realization of such systems in particular with regard to the direct integration into other microsystems, such as micromass spectrometers, for example in so-called PIMMS systems, is particularly advantageous. Because in this structure, channels can be formed, through which a gas escaping from a mass spectrometer can be directed. In addition, uniform or the same manufacturing processes can be used for the entire system.
  • Such a structure can be realized, for example, by the DRIE etching method already mentioned above and described in detail below, in which all components that are critical with respect to geometry and that are electrically conductive can be realized by highly accurate anisotropic etching in silicon.
  • the dynodes can be arranged in two concentrically arranged arcs.
  • the arches can form, for example, circular arcs.
  • the dynodes are expediently arranged such that the electrons are respectively directed from the inner arc to the outer arc and back to the inner arc and so on. This in turn allows a very compact design to be combined with a high amplification power. In this way, e.g. reduce the space requirement of the arrangement and so the manufacturing costs even further.
  • the formation in two concentric arcs should mean, in particular, that all dynodes would be touched by two imaginary concentric arcs, for example circular arcs.
  • the concentric arcs are defined by at least a portion of the dynodes thus arranged.
  • an electrically insulating substrate takes place first, reference being made to the above statements with regard to the secondary electron multiplier with reference to the precise configuration of the substrate.
  • a substrate having a thickness in a range of ⁇ 300 ⁇ m to less than 1000 ⁇ m for example made of glass, sapphire, oxidized silicon or silicon oxide, or a ceramic, can be provided.
  • step b) at least a plurality of dynodes and optionally a detector and optionally at least one focusing electrode are then applied to the electrically insulating substrate to form structures with a maximum spatial extent of the respective individual structure of .gtoreq.50 .mu.m to 1000 .mu.m in each case Extension for a dynode, a focusing electrode and the detector applies.
  • this process step is carried out with a method of microsystem technology to form microsystem components.
  • the dynodes for secondary electron multiplication are arranged according to method step c) as structures, in particular as functional structures, which can be done for example by defined etching, as described in detail below.
  • the exact configuration of the dynodes reference is again made to the above statements concerning the secondary electron multiplier.
  • Arranging the dynodes for secondary electron multiplication is further intended to mean that the dynodes have a shape and orientation that allows a carrier current, such as an electron current, to be reflected or accelerated from dynode to dynode, thus permitting amplification.
  • a carrier current such as an electron current
  • a line structure for connecting the dynodes to the substrate is additionally applied, in particular wherein the line structure has approximately metallic interconnects, shields optionally arranged therebetween, and optionally resistors, so that the be able to supply different dynodes, each with different electrical potential.
  • the conductive structures may be deposited by deposition techniques such as chemical vapor deposition (CVD), physical vapor deposition (PVD), vapor deposition, or sputtering, as described in detail below.
  • a particularly simple and cost-effective production of a secondary electron multiplier can be made possible, wherein in particular a separate adjustment step of the individual components can be dispensed with each other.
  • the shape and position of the dynodes can be generated to less than 1 .mu.m and with each other in the plane of any geometry and arrangement to each other, which allows the production of a particularly defined structure.
  • a high gain can furthermore be realized, since this requires that the electron-optical components, that is to say the dynodes, of a secondary electron multiplier are optimally adjusted or aligned with one another. If the size of the components used, as well as their distances from one another, also reduces the requirements on the geometric tolerances in the dynode shape and adjustment.
  • the components of a secondary electron multiplier as described above meet these requirements due to the exact manufacturability problem-free, since a subsequent adjustment due to the production-related exact, immediately in the production taking place alignment is not necessary. This also allows any arrangement of the dynodes to each other.
  • the orientation of the components relative to each other can be carried out depending on the specific manufacturing process and thereby for example by a photomaskator alignment of the dynodes by the arrangement of these directly during manufacture, so that an additional adjustment step or an additional alignment can be prevented or may be superfluous.
  • the adjustment takes place directly in the production of the corresponding structures by a defined orientation or arrangement.
  • a miniaturized precise and in the lateral geometry arbitrarily selectable electrode / dynode geometry or shape can allow due to the manufacturing process, which can allow a particularly good adaptability.
  • the conductor structure, as well as the shields can also be produced in an integrated manner by deposition and patterning of printed conductors, for example by depositing layers of titanium (Ti), nickel (Ni), chromium (Cr), gold (Au ), Copper (Cu), silver (Ag), platinum (Pt) or palladium (Pd), preferably by direct contacting of the Electrodes and dynodes are integrated into the process.
  • the production of the voltage divider required for the supply of the dynodes with ascending potentials can also be implemented integrated in terms of circuitry between the dynodes.
  • resistors preferably of materials with a high specific resistance, but preferably still a positive temperature coefficient.
  • Non-limiting examples of the design of the resistors include, for example, titanium oxynitride (TiON), nickel-chromium alloys (NiCr) or copper-nickel-manganese alloys (CuNiMn), for example, constantan.
  • these secondary electron multipliers can also be integrated directly into these systems. They not only allow a simplified simultaneous production, they can also be integrated without losses of charge carriers to be amplified because of the thus avoidable dead volumes and highly accurate assignment, for example by using photomask-based geometries.
  • thermodynamic equilibrium silicon dioxide (SiO 2 ), (Al 2 O 3 ), zinc oxide (ZnO) or amorphous diamond, for example for coating the dynodes
  • materials can be integrated into the process for coating the dynodes, for example by thin-film processes, such as PVD processes, sputtering and vapor deposition, or by chemical vapor deposition (CVD).
  • At least one process step may be performed using a photolithography process.
  • a photolithography process may serve in particular for defining the structures, in particular the dynodes, the line structure, shields, the detector and the at least one focusing electrode.
  • the production of all structures arranged on a substrate may be based on a photolithography step.
  • a surface of a base body such as a silicon wafer, for example of doped silicon or glass, is provided in a conventional manner with a layer of a photoresist.
  • a negative varnish is to be understood in a manner known per se as meaning a varnish whose solubility decreases as a result of exposure
  • a positive varnish is to be understood as meaning a varnish whose solubility increases as a result of exposure.
  • a positive or a negative resist can be done by a partially UV-transparent mask exposing the paint layer, which changes the solubility and the corresponding areas can be removed or remain stable, such as by the action of a solvent, such as acetone, or a plasma.
  • the structure of the mask is then transferred directly or as a negative into the lacquer layer, so that it can serve as the basis for generating the corresponding structures.
  • Such a processed basic body can then be the basis for further process steps for generating the desired structures.
  • a photoresist may be applied by masking us structured removal by photolithography on the positions where no material of the line structure is to be present. Subsequently, a layer of the material of the line structure can be applied, for example by means of physical vapor deposition, chemical vapor deposition, sputtering or vapor deposition, whereupon the photoresist is removed again. This can be done for example by introduced channels or a lateral treatment. As a result, the material on the photoresist also dissolves.
  • a photoresist can be applied, which has only a reduced adhesion of the material to be applied. The applied material then only adheres to the positions next to the photoresist, whereupon it can be removed again.
  • At least one process step can be carried out using a reactive ion etching.
  • a reactive ion deposition also known as the DRIE process (deep reactive ion etching)
  • DRIE process deep reactive ion etching
  • a reactive ion deep etching in particular proceed as follows. First of all, the base body can be masked, for example with a photoresist, as explained above, or with a hard mask, such as silicon dioxide, covering the regions which are not to be etched.
  • the exposed regions are etched, for example, using reactive hexane based on sulfur hexafluoride (SF 6 ) in argon (Ar), which may be generated by, for example, forming a sulfur hexafluoride based plasma and argon based plasma.
  • SF 6 sulfur hexafluoride
  • Ar argon
  • an etching substep may alternate with a substep of the passivation.
  • the etched surface can be protected with a passivation layer, such as formed by the application of Teflon or by bringing the etched surface into contact with octafluorocyclobutane (C 4 F 8 ).
  • a highly accurate structure can be etched.
  • the method described above is also known as the Bosch process. This method is thus particularly suitable if the structures, such as the dynodes, the detector and / or the at least one conversion electrode are to be formed from doped silicon.
  • the entire structural parts to be removed can be removed by etching, or only trenches can be etched.
  • this can be removed, so that the areas to be removed no longer stop own on the substrate and so can fall out.
  • the corresponding structure etched from the bottom or the corresponding edges are etched, so that not the entire structure to be removed needs to be etched out, but only the edges can be traversed, so that the corresponding structures can be separated out ,
  • step b) all components which are critical with respect to geometry and electrically conductive can preferably be realized by highly accurate anisotropic etching in silicon, which are in particular hermetically connected to insulating substrates provided with electrical conductors, for example by anodic bonding or anodic bonding.
  • silicon which are in particular hermetically connected to insulating substrates provided with electrical conductors, for example by anodic bonding or anodic bonding.
  • a particular alkali ion-containing glass substrate can be brought into close contact with the doped silicon and a voltage introduced from the outside into the glass or into the silicon such that the glass substrate negative and the silicon structure are positively charged.
  • a voltage introduced from the outside into the glass or into the silicon such that the glass substrate negative and the silicon structure are positively charged.
  • electrodes connected to a voltage source can be used or a heating plate can serve as an electrode.
  • chemical compounds can form between the silicon and glass, such as the oxygen from the silica of the glass, creating a stable bond.
  • At least one method step can be carried out using a galvanic material structure.
  • a so-called LIGA method can be carried out or the method can be based thereon.
  • substantially the following steps are taken.
  • the substrate which in turn may be a glass substrate or a ceramic substrate, is provided with a metallic layer, such as by sputter deposition or vapor deposition. A photoresist may subsequently be applied to this layer, as described in detail above with reference to photolithography.
  • a negative mold of the structure to be applied may remain as a metallic pattern next to the remaining paint.
  • a metal can be deposited on the substrate in the areas in which the photoresist was removed during the development, that is, the metallic pattern has been exposed.
  • the substrate, the metallic layer and the electrodeposited metal first remain behind.
  • the electrodeposited metal can form the desired structures in this case.
  • the metallic layer which is located directly on the substrate is then removed by an etching step, for example, between the galvanized structures. This method is therefore particularly suitable when the structures, such as the dynodes, the detector and / or the at least one conversion electrode should be formed from a metal.
  • FIG. 1 is a schematic representation of a preliminary stage of an embodiment of a photomultiplier 10 shown.
  • a substrate 12 is shown, which may be formed, for example, from glass, sapphire, silicon oxide or ceramic.
  • the substrate 12 may have a thickness which lies in a range of less than 1000 ⁇ m, for example greater than 300 ⁇ m, for example at 500 ⁇ m. Further, it may have a width or length which may be adapted to the number of components applied.
  • a plurality of discrete dynodes 14 are applied, wherein the individual dynodes 14 may have dimensions in a range of ⁇ 50 ⁇ m to ⁇ 500 ⁇ m.
  • the dynodes 14 may each have a width in a range of ⁇ 50 ⁇ m to ⁇ 200 ⁇ m and / or a length of ⁇ 50 ⁇ m to 400 ⁇ m and / or a thickness of ⁇ 100 ⁇ m to ⁇ 500 ⁇ m.
  • FIG. 1 It is shown that the dynodes 14 are arranged in two parallel rows with six dynodes 14 each.
  • the distance between the dynodes 14 to each other may be in a range of ⁇ 10 ⁇ m to ⁇ 500 ⁇ m.
  • the spacing of the dynodes in one row may be, for example, in a range of ⁇ 10 ⁇ m to ⁇ 40 ⁇ m, approximately 20 ⁇ m, and / or the spacing of the dynodes 14 to dynodes 14 arranged in the parallel row may be in a range of ⁇ 10 ⁇ m to ⁇ 150 ⁇ m. about 100 ⁇ m, lie.
  • the aforementioned values can relate in particular to use at a pressure of ⁇ 10 -4 Pa to ⁇ 1 Pa.
  • the dynodes 14 may be configured, for example, with a thickness in a range of ⁇ 100 ⁇ m to ⁇ 500 ⁇ m, approximately to ⁇ 400 ⁇ m, for example 300 ⁇ m.
  • a detector 16 and focusing electrodes 18 are shown which may have a thickness comparable to the dynodes 14. Furthermore, the detector 16 and the focusing electrodes 18 may be in a comparable maximum size range as the dynodes 14. Furthermore, the dynodes 14, as well as the detector 16 and the focusing electrodes 18 may be made of doped silicon or of a metal such as gold or silver. The dynodes 14 may have a coating for effective reinforcement, such as alumina or silica. The dynodes 14, the detector 16 and the focusing electrodes 18 are manufactured by a microsystem method.
  • FIG. 1 further shows that on the dynodes 14, the focusing electrodes 18 and, not shown, on the detector 16, tracks 20 are arranged which may be part of a line structure to bring the dynodes 14 to a desired and mutually different electrical potential .
  • tracks 20 are arranged which may be part of a line structure to bring the dynodes 14 to a desired and mutually different electrical potential .
  • the electrical potential of the individual dynodes 14 can be set in a defined manner and, in particular, different from one another, are in the FIG. 2 further thin-film resistors 26 are shown, which may be arranged between the dynodes 14.
  • shields 15 are shown, which may be arranged between the tracks 20 so as to prevent electrical flashovers.
  • the shields 15 can be produced analogously to the electrodes or the line structures, such as the conductor tracks 20, but an electrical connection of the shields does not take place.
  • the above-described arrangement is furthermore preferably arranged in a chamber 22 bounded by a wall 23 approximately made of a plastic, in which a vacuum 24 can be formed, as shown purely schematically in the figures. It may also be provided that in the chamber 22, a further chamber is provided, in which the arrangement comprising the substrate 12 is arranged with the components applied thereto. This chamber may in turn have a window or an opening for introducing a beam to be amplified, wherein in the not Chamber shown also the vacuum 24 can be introduced.
  • the further chamber may again have a wall made of a plastic.
  • a charged particle beam 11 is shown, which is passed through the focusing electrodes 18, which may also have a suitable electrical potential, to the dynodes 14, wherein the charged particle beam 11 amplifies in the direction of the detector 16.
  • a photosensitive layer or photoelectron emitter layer for example, upstream of the focusing electrodes 18 and / or, for example, on the substrate 12 in order to generate the charged-particle beam 11.
  • the beam source of the charged particle beam 11 may be located directly in the chamber 22.
  • the secondary electron multiplier 10 has a layer structure in which two substrates 12, 12 'are provided, between which at least the dynodes 14 and according to FIGS Figures 3 and 4 Furthermore, the detector 16 are arranged. Further, a made of a plastic wall 25 is shown, which closes a chamber 27, the chamber 27 corresponding to FIG. 1 can be arranged in a chamber 22, not shown, for forming a vacuum 24 In this case, the vacuum 24 is also in the chamber 27 before.
  • the wall 25 may be configured circular and together with the substrates 12, 12 ', the chamber 27 form.
  • the interconnects 20 may be metal interconnects made of a nickel-gold multilayer system and may be connected approximately eutectically to the dynodes 14. Through these tracks 20 contacting can be done to the outside, for example, to a board.
  • the gain beam 11 is shown, which is passed to the dynodes 14, wherein the gain beam 14 amplifies in the direction of the detector 16.
  • the in FIG. 4 not shown chamber 22 and the wall 23, not shown also have a transparent or transparent area.
  • a photoelectron emitter layer is provided, which may be arranged approximately on the substrate 12.
  • the chamber 27 may be opened if an electron beam is to be amplified and the beam source is outside the chamber 27.
  • focussing electrodes may be provided, which may be arranged or aligned in accordance with the formation of the amplifying beam 11.
  • FIG. 4 Furthermore, an interconnection of the individual electrodes is not shown. However, this can be done in a manner understandable to the skilled person described above and for a secondary electron multiplier basically known manner.

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  • Electron Tubes For Measurement (AREA)
EP15194327.1A 2014-11-17 2015-11-12 Multiplicateur d'electrons secondaire et son procede de fabrication Withdrawn EP3021351A1 (fr)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111236926A (zh) * 2018-11-29 2020-06-05 斯伦贝谢技术有限公司 井下工具内的高电压保护和屏蔽

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2409927A (en) * 2004-01-09 2005-07-13 Microsaic Systems Ltd Micro-engineered electron multipliers
EP1717842A1 (fr) * 2004-02-17 2006-11-02 Hamamatsu Photonics K.K. Photomultiplicateur
US20100213837A1 (en) * 2009-02-25 2010-08-26 Hamamatsu Photonics K.K. Photomultiplier tube
US20120091890A1 (en) * 2010-10-14 2012-04-19 Hamamatsu Photonics K.K. Photomultiplier tube
US20120091316A1 (en) * 2010-10-14 2012-04-19 Hamamatsu Photonics K.K. Photomultiplier tube

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2409927A (en) * 2004-01-09 2005-07-13 Microsaic Systems Ltd Micro-engineered electron multipliers
EP1717842A1 (fr) * 2004-02-17 2006-11-02 Hamamatsu Photonics K.K. Photomultiplicateur
US20100213837A1 (en) * 2009-02-25 2010-08-26 Hamamatsu Photonics K.K. Photomultiplier tube
US20120091890A1 (en) * 2010-10-14 2012-04-19 Hamamatsu Photonics K.K. Photomultiplier tube
US20120091316A1 (en) * 2010-10-14 2012-04-19 Hamamatsu Photonics K.K. Photomultiplier tube

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111236926A (zh) * 2018-11-29 2020-06-05 斯伦贝谢技术有限公司 井下工具内的高电压保护和屏蔽

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