WO2001067482A1 - Hollow cathode sputter ion source for generating high-intensity ion beams - Google Patents

Hollow cathode sputter ion source for generating high-intensity ion beams Download PDF

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Publication number
WO2001067482A1
WO2001067482A1 PCT/EP2001/000996 EP0100996W WO0167482A1 WO 2001067482 A1 WO2001067482 A1 WO 2001067482A1 EP 0100996 W EP0100996 W EP 0100996W WO 0167482 A1 WO0167482 A1 WO 0167482A1
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cathode
sputtering
hollow cathode
ion source
cavity
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PCT/EP2001/000996
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German (de)
French (fr)
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Michael Müller
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Gesellschaft für Schwerionenforschung mbH
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Priority to AU2001237357A priority Critical patent/AU2001237357A1/en
Priority to EP01909713A priority patent/EP1261982A1/en
Publication of WO2001067482A1 publication Critical patent/WO2001067482A1/en

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J27/00—Ion beam tubes
    • H01J27/02—Ion sources; Ion guns
    • H01J27/04—Ion sources; Ion guns using reflex discharge, e.g. Penning ion sources
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J27/00—Ion beam tubes
    • H01J27/02—Ion sources; Ion guns
    • H01J27/20—Ion sources; Ion guns using particle beam bombardment, e.g. ionisers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
    • H01J37/02—Details
    • H01J37/04—Arrangements of electrodes and associated parts for generating or controlling the discharge, e.g. electron-optical arrangement, ion-optical arrangement
    • H01J37/08—Ion sources; Ion guns

Definitions

  • the invention relates to an ion source for generating ion beams of high intensity and medium charge at beam voltages around 25 kV.
  • the ions are generated by sputtering the respective material, preferably metals, using the plasma of a Penning discharge (Penning or Philips Ionization Vacuum Gauge, PIG).
  • Multiply charged ions are generated in Penning ion sources; they serve inter alia as internal ion sources for cyclotrons and as powerful ion sources for linear heavy ion accelerators, for example UNILAC, GSI-Darmstadt 1 '.
  • Ion sources which use the evaporation of the materials to generate free particles (see 1) , p 331 ff). This produces ion beams with little energy scatter from the beam particles.
  • One example is the surface ion source for cesium ion beams with thermal energy distribution, because the positively charged Cs ions are vaporized here because of the low binding of the light electron and the interaction with the tungsten carrier material.
  • Evaporative ion sources have been manufactured for a large number of applications since the advent of ion accelerator technology. This was driven by special alignments in the objective, such as mass spectroscopy, nuclear physics, implantation technology and surface physics. There were often major technical difficulties, such as those associated with mastering high temperatures.
  • the Penning discharge takes place on an axis parallel to the field lines of a magnetic field between two solid cathodes, for example made of W, Ta or Mo, within a hollow anode, whereby normally one of the cathodes is heated indirectly to the emission temperature by electron bombardment to facilitate ignition of the discharge and to increase the discharge current density.
  • the space between these two cathodes is filled by the positive column of the plasma and enclosed by the hollow anode.
  • the ion beam is extracted from the hollow anode through a slit-shaped window.
  • ions of the cathode material are also generated. This is a sometimes undesirable but unavoidable side effect in the secondary electron generation, which is essential for the discharge, by ion bombardment of the cathodes, via the two cathode cases of the discharge. Constructive measures have been taken for the Penning source to prevent the sputtered cathode material from entering the extractable aode plasma.
  • Penning discharge typically tends to form higher charge states, especially when high discharge powers are required to generate high beam currents.
  • Ion sources in which the sputtering effect is used to generate free particles have the advantage that the generation of free particles takes place practically at room temperature, largely bypassing metal chemistry at high temperatures.
  • the relatively large energy spread of the particles in the extracted beam is disadvantageous.
  • An example of a typical sputtering source is the Müller-Hortig 3 'ion source. It is used to generate beams of simply charged, negative ions of almost all elements and a large number of chemical molecular fragments, eg anions, for use on tandem Van DeGraaff accelerators.
  • the object of the invention is to generate intense ion beams from solid-state elements, in particular from metals and at the same time to achieve a better economy in terms of material consumption than that of the sputtering Penning ion sources or duopotatron ion sources 41 .
  • the object is achieved by a hollow cathode sputter ion source with the features of claim 1 (half-PIG geometry) or claim 2 (full-PIG geometry).
  • a Penning plasma is initially formed in the noble gas atmosphere in the Half-PIG ion source.
  • the plasma guided by the magnetic field, penetrates into the axially extending channel in the anti-cathode, and an interface is formed between the channel wall and the plasma.
  • the potential difference of the cathode case which corresponds approximately to the discharge voltage, lies above this boundary layer.
  • positive ions of the plasma hit the wall of the channel and are sputtered, among other things. neutral atoms of the wall material free. These get into the plasma unhindered and are ionized there by fast electrons.
  • the fast electrons are generated both by the hot cathode of the Penning discharge and by ion bombardment of the channel wall and are accelerated into the plasma in the cathode cases.
  • the boundary layer is correspondingly large, for example the area of the inner wall of the channel, so that through a breakthrough in the channel wall sufficient ions of the plasma reach the extraction area of a strong electrical field installed outside the discharge geometry to form an ion beam.
  • This Ions also have to pass the cathode case and are accelerated out of the plasma in the beam direction.
  • the highest ion currents can be expected from lighter elements and from elements with a high sputtering rate and low ionization potential.
  • the material from which the sputtered hollow cathode is made, or the inner wall of which is sufficiently coated for the purpose, must be a solid material and be able to emit sufficient secondary electrons under ion bombardment.
  • Most solid elements are metals.
  • carbon is also a solid material but not a metal.
  • Related elements, such as Ni, Cr, Fe, Ti, Mo, etc. show a relatively uniform behavior with regard to ion source operation and ion yield. Elemental lead is problematic, it has a high sputtering rate, but is obviously unsuitable as a cathode material.
  • Different crystal formations of the same element, e.g. B. Si single crystal can have very different sputtering properties, which then favor or reduce the ion yield.
  • a Penning plasma (claim 1) or two Penning plasmas (claim 2) are used for the generation of free particles and for their ionization.
  • Penning plasmas are particularly well suited for this because of their high particle density (> 10 13 / cm 3 ) and because of the increased ionization probability due to the electron pendulum effect which is characteristic of Penning plasmas.
  • the ion beam is formed by radial extraction from a cathode, by means of an electric field of 100 kV / cm perpendicular to the magnetic axis or the ion source axis.
  • ions can be caused by a slot-shaped, preferably axially parallel opening in the wall, the emission gap extracted from the plasma inside.
  • the arrangement of a hot cathode, a short anode and an anti-cathode with a cylindrical cavity has the internal working name Half-PIG (half Penning or Philips Ionization Vacuum Gauge, PIG) (claim 1).
  • Claim 2 basically characterizes the arrangement of two cathodes, each with associated anodes. At least one of the two cathodes is heated. Between the two anodes is the sputtering hollow cathode with a cylindrical cavity, which is a common anti-cathode with regard to the two Penning discharges. The longitudinal axis of the cavity passes through the two cathodes and is parallel to the axis of the magnetic field.
  • Full-PIG whole Penning or Philips Ionization Vacuum Gauge, PIG
  • Half-PIG is a real alternative, because 1/3 less magnetic gap is required.
  • Half-PIG delivers high ion currents of the same order of magnitude as Full-PIG from the sputtered materials.
  • the ion beam is extracted from the sputtering hollow cathode radially through the opening parallel to the axis.
  • the two cathodes are normally galvanically connected (FIG. 3), as is the case in the normal operating case of the Half-IG or Full-PIG ion source.
  • the circuit, formed from hollow sputter cathode - anti-cathode in both versions - and anode is supplied by its own, independently triggerable and adjustable power supply unit, with the advantage that these additional parameters influence the beam distribution in the direction of the longitudinal slot axis can.
  • the importance of this parameter depends very much on the demands placed on the ion beam and only comes into play in the complex operation of a system.
  • the circuit (s) formed from the hot or cold cathode (s) and the anode (s) of the Penning discharge (s) are / are supplied by a separate, independently triggerable power supply unit (claim 5).
  • Claim 8 describes a possible structure of the sputtering hollow cathode.
  • This is usually a heat-conducting, coolant-flowing carrier made of, for example, copper, on which the actual electrode, the sputtering hollow cathode, is fastened with good heat transfer.
  • the inner wall of the z. B. tubular cavity either consists of the desired element from which the radiation ions are to be obtained, or is coated with it. The latter type of electrode production can be used if ion beams are to be generated from very expensive or rare elements, such as enriched or pure ones Isotopes.
  • the magnetic field is generated via a permanent magnet (claim 9), an electromagnet (claim 10 or via a superconducting magnet (claim 11).
  • the material of the channel wall must also have good properties with regard to secondary electron emission;
  • the hollow cathode sputter ion source is characterized by: i. the radial extraction of the ion beam from the hollow sputter cathode to the cavity axis through the axially parallel opening, ii. the high ion beam intensities, see table of results below, in the single pulse up to repetition rates around 100 / sec, iii. the high efficiency of material consumption, approx. 2% compared to the Penning ion source of only approx. 0.02% iv. the low oscillation component in the ion beam signal, also called hash or noise, in comparison to classic Penning ion sources.
  • the sputtering hollow cathode geometry is particularly important for the economy and long-term constancy of ion source operation. part.
  • the sputtered neutral particles get into the plasma and are ionized there by fast electrons. Now, also accelerated in the cathode case, they can either leave the electrode through the emission window or by "self-sputtering", or by "sticking" on the channel wall the Io - support the production process. Non-ionized neutral particles also hit the inner wall of the electrode and are therefore still present in the production process. This represents a significant economic advantage over the conventional sputtering Penning source in which most of the particles that are not extracted as ions are lost for further ion generation.
  • FIG. 1 shows the half-PIG configuration
  • FIG. 2 shows the full PIG configuration
  • FIG. 3 shows the basic circuit diagram of the half-PIG configuration
  • Figure 4 shows the schematic diagram of the full PIG configuration.
  • the modular, mechanical concept of the GSI Penning ion source was used to implement the mechanics of the prototype of the new ion source. This concept is an unpublished GSI internal standard of the development status from December 1989.
  • the upper cathode of the ion source is heated indirectly.
  • the intensely cooled short anode follows on the axis downwards.
  • the electrode of the sputtering hollow cathode, the anti-cathode, is used on an insulated bushing with good heat transfer.
  • the following anode is basically in the half-PIG version is not necessary but is advantageous for the uniform gas balance of the discharge.
  • the hot cathode anode circuit is formed via the power supply NG1.
  • the hollow cathode is galvanically connected to the hot cathode.
  • the reference potential is the anode (plus).
  • the potential is for optimal operation, i.e. good ion beam quality and - yield adjustable.
  • the duty cycle can be set within wide limits.
  • Typical for high-current linear accelerators as injectors for synchrotrons are repetition rates from 1 / s to 10 / s with a pulse length of 0.5 ms to 2 ms.
  • FIG. 1 shows the half-PIG geometry in which the asymmetrical ion source structure
  • Half-PIG uses only a part of the volume of the hollow cylinder of the sputtering hollow cathode during operation.
  • the length of the hollow sputter cathode can be adapted to the technical circumstances.
  • the band-shaped ion beam of positively charged ions extracted from the axially parallel slot or breakthrough in the wall of the sputtering hollow cathode has essentially the width of the length of the plasma column which is visible through the breakthrough, here 45 mm.
  • the electrode body of the hollow cathode has a length of 60 mm, the anode length here is 18 mm to show the contour of one of many possible machine-specific geometries.
  • FIG. 1 shows the case of the operation of the ion source in the inhomogeneous magnetic field of the ion source magnet of the compact PIG ion source 5 '.
  • the Magnetfeldach.se is parallel to the longitudinal axis of the hollow cylinder of the sputtering hollow cathode.
  • the magnetic field shape is similar to a magnetic bottle with the ratio of the force flux density:
  • the cathodes full PIG version see below
  • the sputtering hollow cathode is installed in the area of the bottle belly.
  • the magnetic field axis was merged with the longitudinal axis of the hollow cylinder. Both axes can be shifted parallel to each other as needed to optimize the beam, but this involves some technical effort.
  • FIG. 2 The geometry in FIG. 2 can be imagined by mirroring the half-PIG geometry on a plane running perpendicular to the axis of the sputtering hollow cathode.
  • the result is the symmetrical ion source structure Full-PIG, consisting of two Penning discharge geometries, which, arranged on a common axis, use a common anti-cathode.
  • the two Penning plasmas together starting in volume from the respective hot cathode / cold cathode, reaching as far as the center of the cylindrical cavity of the sputtering hollow cathode as an anti-cathode, since this is a mirror image of the center plane, fill the entire cylindrical space between the cathodes, the two anodes and in the sputtering hollow cathode.
  • the band-shaped ion beam of positive ions extracted radially from the hollow sputter cathode has a width which corresponds to the length of the axial opening in the hollow sputter cathode and is also symmetrical to the center position of the magnetic field and the discharge geometry in accordance with the electrode position and electrode geometry. Both configurations, half-PIG and full-PIG, have in common the radial extraction of a beam of positively charged ions in the form of a band-shaped beam. With the same gap or breakthrough geometry in the sputtering hollow cathode, they differ in the width of the ion beam and also in the intensity.
  • Magnetic field force flux density of the magnetic field of the ion source ion current: pulse amplitude of the ion beam current after analysis
  • Pulse length duration of the discharge pulse

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  • Combustion & Propulsion (AREA)
  • Analytical Chemistry (AREA)
  • Electron Sources, Ion Sources (AREA)

Abstract

The sputter hollow cathode geometry is particularly advantageous in terms of the economy and long-term consistency of the ion source operation. The sputtered neutral particles reach the plasma, are ionised by rapid electrons and can then, accelerated during the cathode drop, either leave the electrode through the emission window, or support the ion production process by 'self-sputtering' or also by 'sticking' on to the channel wall. Non-ionised neutral particles also strike the inner wall of the electrode and thus remain present in the production process. The invention has economic advantages in relation to the conventional Penning sputter source, in which the majority of particles that are not extracted as ions are lost for further ion production.

Description

Hohlkathoden-Sputter-Ionenquelle zur Erzeugung von Ionenstrahlen hoher IntensitätHollow cathode sputter ion source for generating high intensity ion beams
Die Erfindung betrifft eine Ionenquelle zur Erzeugung von lonenstrahlen hoher Intensität und mittlerer Ladung bei Strahlspannungen um 25 kV. Die Ionenerzeugung erfolgt durch Sputtering des jeweiligen Materials, vorzugsweise Metalle, mit Hilfe des Plasmas einer Penning-Entladung (Penning or Philips Ionization Va- cuum Gauge, PIG) .The invention relates to an ion source for generating ion beams of high intensity and medium charge at beam voltages around 25 kV. The ions are generated by sputtering the respective material, preferably metals, using the plasma of a Penning discharge (Penning or Philips Ionization Vacuum Gauge, PIG).
Zum Betrieb der Penning-Entladung werden Edelgase verwendet; für höhere Ladungszustände ist Neon günstig aber auch schwerere Edelgase finden Anwendung.Noble gases are used to operate the Penning discharge; neon is cheap for higher charge states, but heavier noble gases are also used.
In Penning-Ionenquellen werden mehrfach geladene Ionen erzeugt; sie dienen u.a. als interne Ionenquellen für Zyklotrone und als leistungsfähige Ionenquellen für lineare Schwerionen-Beschleuniger, z.B. UNILAC, GSI-Darmstadt1' .Multiply charged ions are generated in Penning ion sources; they serve inter alia as internal ion sources for cyclotrons and as powerful ion sources for linear heavy ion accelerators, for example UNILAC, GSI-Darmstadt 1 '.
Bekannt sind Ionenquellen, welche die Verdampfung der Materialien zur Erzeugung freier Teilchen benutzen (siehe 1) , S 331 ff). Damit werden Ionenstrahlen mit geringer Energiestreuung der Strahlteilchen erzeugt. Ein Beispiel ist die Oberflächenionen- quelle für Cäsium-Ionen-Strahlen mit thermischer Energieverteilung, da hier wegen der geringen Bindung des Leuchtelektrons und der Wechselwirkung mit dem Trägermaterial Wolfram direkt positiv geladene Cs-Ionen abgedampft werden. Verdampfungsionenquellen sind für eine große Anzahl von Anwendungen seit dem Beginn der Ionenbeschleunigertechnik hergestellt worden. Antrieb dazu waren spezielle Ausrichtungen in der Zielsetzung, wie Massenspektroskopie, Kernphysik, Implantationstechnik und Oberflächenphysik. Häufig waren große technische Schwierigkeiten, wie sie mit der Beherrschung hoher Temperaturen verbunden sind zu bewältigen.Ion sources are known which use the evaporation of the materials to generate free particles (see 1) , p 331 ff). This produces ion beams with little energy scatter from the beam particles. One example is the surface ion source for cesium ion beams with thermal energy distribution, because the positively charged Cs ions are vaporized here because of the low binding of the light electron and the interaction with the tungsten carrier material. Evaporative ion sources have been manufactured for a large number of applications since the advent of ion accelerator technology. This was driven by special alignments in the objective, such as mass spectroscopy, nuclear physics, implantation technology and surface physics. There were often major technical difficulties, such as those associated with mastering high temperatures.
Die Penning-Entladung findet auf einer Achse parallel zu den Feldlinien eines Magnetfeldes zwischen zwei massiven Kathoden, aus z.B. W, Ta oder Mo, innerhalb einer Hohlanode statt, wobei normalerweise eine der Kathoden zum leichteren Zünden der Entladung und zur Steigerung der Entladungsstromdichte indirekt durch Elektronenbombardement auf Emissionstemperatur geheizt wird. Der Raum zwischen diesen beiden Kathoden wird von der positiven Säule des Plasmas erfüllt und von der Hohlanode eingeschlossen. Aus der Hohlanode wird der Ionenstrahl über ein schlitzförmiges Fenster extrahiert.The Penning discharge takes place on an axis parallel to the field lines of a magnetic field between two solid cathodes, for example made of W, Ta or Mo, within a hollow anode, whereby normally one of the cathodes is heated indirectly to the emission temperature by electron bombardment to facilitate ignition of the discharge and to increase the discharge current density. The space between these two cathodes is filled by the positive column of the plasma and enclosed by the hollow anode. The ion beam is extracted from the hollow anode through a slit-shaped window.
In einer Hochleistungs-Penning-Entladung2) , bis 30 kW im Puls, werden auch Ionen des Kathodenmaterials erzeugt. Das ist ein bisweilen unerwünschter aber unvermeidbarer Nebeneffekt bei der für die Entladung lebenswichtigen Sekundärelektronenerzeugung durch das Ionenbombardement der Kathoden, über die beiden Kathodenfälle der Entladung. Für die Penning-Quelle sind konstruktive Maßnahmen getroffen, um zu verhindern, dass das gesputterte Kathodenmaterial in das extrahierbare Aodenplasma gelangt.In a high-performance Penning discharge 2) , up to 30 kW in the pulse, ions of the cathode material are also generated. This is a sometimes undesirable but unavoidable side effect in the secondary electron generation, which is essential for the discharge, by ion bombardment of the cathodes, via the two cathode cases of the discharge. Constructive measures have been taken for the Penning source to prevent the sputtered cathode material from entering the extractable aode plasma.
Grundsätzlich ist es mit Penning-Ionenquellen möglich auch niedrig geladene Ionen zu erzeugen, jedoch tendiert die Penning-Entladung typisch zur Bildung höherer Ladungszustände besonders dann, wenn zur Erzeugung hoher Strahlströme auch hohe Entladungsleistungen erforderlich werden.Basically, it is possible to generate low-charge ions with Penning ion sources, but Penning discharge typically tends to form higher charge states, especially when high discharge powers are required to generate high beam currents.
Ionenquellen, bei denen der Sputtereffekt zur Erzeugung freier Teilchen benutzt wird, haben den Vorteil, dass die Erzeugung freier Teilchen praktisch bei Zimmertemperatur unter weitgehender Umgehung der Metallchemie bei hohen Temperaturen erfolgt. Nachteilig ist die relativ große Energiestreuung der Teilchen im extrahierten Strahl. Ein Beispiel für eine typische Sputterio- nenquelle ist die Ionenquelle nach dem Müller-Hortig-Prinzip3' . Sie dient zur Erzeugung von Strahlen einfach geladener, negativer Ionen fast aller Elemente und einer Vielzahl chemischer Molekülfragmente, z.B. Anionen, für die Anwendung an Tandem-Van- DeGraaff-Beschleunigern.Ion sources in which the sputtering effect is used to generate free particles have the advantage that the generation of free particles takes place practically at room temperature, largely bypassing metal chemistry at high temperatures. The relatively large energy spread of the particles in the extracted beam is disadvantageous. An example of a typical sputtering source is the Müller-Hortig 3 'ion source. It is used to generate beams of simply charged, negative ions of almost all elements and a large number of chemical molecular fragments, eg anions, for use on tandem Van DeGraaff accelerators.
Der Erfindung liegt die Aufgabe zugrunde, intensive Ionenstrahlen von Festkörperelementen besonders von Metallen zu erzeugen und gleichzeitig im Hinblick auf den Materialverbrauch eine bessere Ökonomie als die der Sputter-Penning-Ionenquellen oder Duo- pigatron-Ionenquellen41 zu erreichen.The object of the invention is to generate intense ion beams from solid-state elements, in particular from metals and at the same time to achieve a better economy in terms of material consumption than that of the sputtering Penning ion sources or duopotatron ion sources 41 .
Die Aufgabe wird durch eine Hohlkathoden-Sputter-Ionenquelle mit den Merkmalen des Anspruchs 1 (Half-PIG-Geometrie) oder Anspruchs 2 (Full-PIG-Geometrie) gelöst.The object is achieved by a hollow cathode sputter ion source with the features of claim 1 (half-PIG geometry) or claim 2 (full-PIG geometry).
Der weiterführenden Erläuterung der Ansprüche wird zur Hinführung auf die Vorteile der Hohlkathoden-Sputter-Ionenquelle die Beschreibung des Ionenerzeugungsprozesses vorangestellt. Am Beispiel der noch zu erläuternden Half-PIG Geometrie werden die physikalischen Zusammenhänge des Entstehungsvorgangs der Ionen dargestellt :The further explanation of the claims is preceded by the description of the ion generation process in order to point out the advantages of the hollow cathode sputtering ion source. Using the example of the Half-PIG geometry, which is yet to be explained, the physical relationships of the ion formation process are shown:
In der Half-PIG Ionenquelle bildet sich zunächst ein Penning- Plasma in der Edelgasathmosphäre. Das Plasma, geführt durch das Magnetfeld, dringt in den axial verlaufenden Kanal in der Antikathode ein, und es bildet sich eine Grenzschicht zwischen Kanalwand und Plasma aus. Über dieser Grenzschicht liegt die Potentialdifferenz des Kathodenfalls, welche ungefähr der Entladungsspannung entspricht. Mit der im Kathodenfall gewonnenen Energie treffen positive Ionen des Plasmas auf die Kanalwand und setzen dort durch Sputtering u.a. neutrale Atome des Wandmaterials frei. Diese gelangen ungehindert in das Plasma und werden dort durch schnelle Elektronen ionisiert. Die schnellen Elektronen werden sowohl durch die heiße Kathode der Penning-Entladung als auch durch das Ionenbombardement der Kanalwand erzeugt und in den Kathodenfällen in das Plasma hinein beschleunigt.A Penning plasma is initially formed in the noble gas atmosphere in the Half-PIG ion source. The plasma, guided by the magnetic field, penetrates into the axially extending channel in the anti-cathode, and an interface is formed between the channel wall and the plasma. The potential difference of the cathode case, which corresponds approximately to the discharge voltage, lies above this boundary layer. With the energy obtained in the cathode case, positive ions of the plasma hit the wall of the channel and are sputtered, among other things. neutral atoms of the wall material free. These get into the plasma unhindered and are ionized there by fast electrons. The fast electrons are generated both by the hot cathode of the Penning discharge and by ion bombardment of the channel wall and are accelerated into the plasma in the cathode cases.
Durch den axial stark verlängerten Kanal in der Antikathode ist die Grenzschicht entsprechend groß, etwa die Fläche der Innenwand des Kanals, so dass durch einen Durchbruch in der Kanalwand ausreichend Ionen des Plasmas in den Extraktionsbereich eines außerhalb der Entladungsgeometrie installierten, starken elektrischen Feldes gelangen, um einen Ionenstrahl zu bilden. Diese Ionen müssen ebenfalls den Kathodenfall passieren und werden dabei aus dem Plasma heraus in Strahlrichtung beschleunigt.Due to the axially greatly elongated channel in the anti-cathode, the boundary layer is correspondingly large, for example the area of the inner wall of the channel, so that through a breakthrough in the channel wall sufficient ions of the plasma reach the extraction area of a strong electrical field installed outside the discharge geometry to form an ion beam. This Ions also have to pass the cathode case and are accelerated out of the plasma in the beam direction.
Wie allen Plasma-Ionenquellen gemeinsam, sind höchste Ionenströme von leichteren Elementen sowie von den Elementen mit hoher Sputterrate und niedrigem Ionisationspotential zu erwarten.As is common to all plasma ion sources, the highest ion currents can be expected from lighter elements and from elements with a high sputtering rate and low ionization potential.
Das Material, aus der die Sputter-Hohlkathode besteht, bzw. deren Innenwand für den Zweck damit hinreichend beschichtet ist, muß ein festes Material sein und unter Ionenbombardement hinreichend Sekundärelektronen emittieren können. Die meisten festen Elemente sind Metalle. Jedoch ist auch Kohlenstoff, ein festes Material aber kein Metall. Verwandte Elemente, wie Ni, Cr, Fe, Ti, Mo, usw., zeigen ein relativ einheitliches Verhalten hinsichtlich des Ionenquellenbetriebs und der Ionenausbeute. Blei in elementarer Form ist problematisch, es hat eine hohe Sputterrate, ist aber als Kathodenmaterial offenbar ungeeignet. Unterschiedliche Kristallformationen des gleichen Elements, z. B. Si- Einkristall, können sehr unterschiedliche Sputtereigenschaften haben, die dann die Ionenausbeute begünstigen bzw. herabsetzen.The material from which the sputtered hollow cathode is made, or the inner wall of which is sufficiently coated for the purpose, must be a solid material and be able to emit sufficient secondary electrons under ion bombardment. Most solid elements are metals. However, carbon is also a solid material but not a metal. Related elements, such as Ni, Cr, Fe, Ti, Mo, etc., show a relatively uniform behavior with regard to ion source operation and ion yield. Elemental lead is problematic, it has a high sputtering rate, but is obviously unsuitable as a cathode material. Different crystal formations of the same element, e.g. B. Si single crystal, can have very different sputtering properties, which then favor or reduce the ion yield.
Bei der Hohlkathoden-Sputter-Ionenquelle werden für die Erzeugung freier Teilchen und für deren Ionisation ein Penning-Plasma (Anspruch 1) oder zwei Penning Plasmen (Anspruch 2) benutzt. Penning-Plasmen sind dafür wegen ihrer hohen Teilchendichte (> 1013/cm3) und wegen der erhöhten Ionisierungswahrscheinlichkeit durch den für Penning-Plasmen charakteristischen Elektronen- Pendel-ffekt besonders gut geeignet. Die Formierung des Ionenstrahls erfolgt durch radiale Extraktion aus einer Kathode, mittels eines senkrecht zur magnetischen Achse bzw Ionenquellenachse gerichteten elektrischen Feldes der Stärke um 100 kV/cm.In the hollow cathode sputtering ion source, a Penning plasma (claim 1) or two Penning plasmas (claim 2) are used for the generation of free particles and for their ionization. Penning plasmas are particularly well suited for this because of their high particle density (> 10 13 / cm 3 ) and because of the increased ionization probability due to the electron pendulum effect which is characteristic of Penning plasmas. The ion beam is formed by radial extraction from a cathode, by means of an electric field of 100 kV / cm perpendicular to the magnetic axis or the ion source axis.
Wenn die kalte Kathode, die Antikathode der Penning-Entla- dung/en, als solche mit einem zylinderförmigem Hohlraum ausgebildet ist, können durch einen schlitzförmigen, vorzugsweise achsparallelen Durchbruch in der Wand, dem Emissionsspalt, Ionen aus dem im Inneren befindlichen Plasma extrahiert werden. Die Anordnung aus einer heißen Kathode, einer kurzen Anode und einer Antikathode mit zylindrischem Hohlraum hat den fachinternen Arbeitsnamen Half-PIG (halbe Penning oder Philips Ionization Va- cuum Gauge, PIG) (Anspruch 1) .If the cold cathode, the anti-cathode of the Penning discharge / s, is designed as such with a cylindrical cavity, ions can be caused by a slot-shaped, preferably axially parallel opening in the wall, the emission gap extracted from the plasma inside. The arrangement of a hot cathode, a short anode and an anti-cathode with a cylindrical cavity has the internal working name Half-PIG (half Penning or Philips Ionization Vacuum Gauge, PIG) (claim 1).
Anspruch 2 kennzeichnet grundsätzlich die Anordnung zweier Kathoden mit jeweils zugeordneten Anoden. Mindestens eine der beiden Kathoden ist beheizt. Zwischen den beiden Anoden liegt die Sputter-Hohlkathode mit zylindrischem Hohlraum, die hinsichtlich der beiden Penning-Entladungen eine gemeinsame Antikathode ist. Die Längsachse des Hohlraums geht durch die beiden Kathoden und liegt parallel zur Achse des Magnetfelds. Für die grundsätzliche Anordnung gemäß Anspruch 2 und der darin enthaltenen Spiegelsymmetrie, wie in Anspruch 3 hervorgehoben, bezüglich der Mittenebene wird der ebenfalls fachinterne Arbeitsname Full-PIG (ganze Penning oder Philips Ionization Vacuum Gauge, PIG) verwendet. In der FULL-PIG Version arbeiten somit zwei Penning-Entladungen auf eine gemeinsame Antikathode, die Sputter-Hohlkathode. In der Full-PIG Version ist die Dichteverteilung längs der Plasmaachse und somit auch die Intensitätsverteilung im Ionenstrahl in vertikaler Richtung aus Symmetriegründen gleichförmiger. Es ist für den Betrieb nicht erforderlich, die Kathode der „gespiegelten" Penning-Entladung extern zu beheizen.Claim 2 basically characterizes the arrangement of two cathodes, each with associated anodes. At least one of the two cathodes is heated. Between the two anodes is the sputtering hollow cathode with a cylindrical cavity, which is a common anti-cathode with regard to the two Penning discharges. The longitudinal axis of the cavity passes through the two cathodes and is parallel to the axis of the magnetic field. For the basic arrangement according to claim 2 and the mirror symmetry contained therein, as emphasized in claim 3, with respect to the center plane, the internal work name Full-PIG (whole Penning or Philips Ionization Vacuum Gauge, PIG) is used. In the FULL-PIG version, two Penning discharges work on a common anti-cathode, the sputtering hollow cathode. In the full PIG version, the density distribution along the plasma axis and thus also the intensity distribution in the ion beam in the vertical direction are more uniform for reasons of symmetry. It is not necessary for the operation to heat the cathode of the “mirrored” Penning discharge externally.
Je nach Einsatzumgebung ist Half-PIG eine echte Alternative, denn es wird 1/3 weniger magnetischer Spalt benötigt. Half-PIG liefert von den gesputterten Materialien hohe Ionenströme in der gleichen Größenordnung wie Full-PIG. Bei beiden Versionen wird der Ionenstrahl aus der Sputter-Hohlkathode radial durch den achsparallelen Durchbruch hindurch extrahiert.Depending on the environment, Half-PIG is a real alternative, because 1/3 less magnetic gap is required. Half-PIG delivers high ion currents of the same order of magnitude as Full-PIG from the sputtered materials. In both versions, the ion beam is extracted from the sputtering hollow cathode radially through the opening parallel to the axis.
Im Penning-Entladungskreis sind die beiden Kathoden normalerweise galvanisch verbunden (Figur 3), so auch im normalen Betriebsfall der Half- IG oder Full-PIG-Ionenquelle . In Anspruch 4 wird beschrieben, daß der Stromkreis, gebildet aus Sputterhohlkathode - Antikathode in beiden Versionen - und Anode durch ein eigenes, unabhängig triggerbares und einstellbares Netzgerät versorgt wird, mit dem Vorteil, durch diesen zusätzlichen Parameter auf die Strahlverteilung in Richtung Spaltlängsachse Einfluß nehmen zu können. Die Bedeutsamkeit dieses Parameters hängt jedoch sehr von den Forderungen an den Ionenstrahl ab und kommt nur im komplexen Betrieb einer Anlage zur Geltung. Auch der/die Stromkreis/e gebildet aus der/den heißen bzw. kalten Kathode/n und den/der Anode/n der Penning-Entladung/en werden/wird von einem separaten unabhängig triggerbaren Netzgerät versorgt (Anspruch 5) .In the Penning discharge circuit, the two cathodes are normally galvanically connected (FIG. 3), as is the case in the normal operating case of the Half-IG or Full-PIG ion source. In claim 4 it is described that the circuit, formed from hollow sputter cathode - anti-cathode in both versions - and anode is supplied by its own, independently triggerable and adjustable power supply unit, with the advantage that these additional parameters influence the beam distribution in the direction of the longitudinal slot axis can. However, the importance of this parameter depends very much on the demands placed on the ion beam and only comes into play in the complex operation of a system. The circuit (s) formed from the hot or cold cathode (s) and the anode (s) of the Penning discharge (s) are / are supplied by a separate, independently triggerable power supply unit (claim 5).
Für den Fall der Full-PIG-Geometrie, Ansprüche 2 und 3, wird es beispielsweise möglich, durch geeignete Pulsverzögerung undIn the case of the full PIG geometry, claims 2 and 3, for example, it becomes possible by suitable pulse delay and
Puls-Triggerung der separaten Stromquellen zwischen den Betriebsmodi :Pulse triggering of the separate power sources between the operating modes:
a) Hohlkathoden-Sputter-Ionenquelle und b) Penning-Ionenquellea) Hollow cathode sputter ion source and b) Penning ion source
in beliebiger Abfolge hin und her zu schalten.switch back and forth in any order.
In den Ansprüchen 6 und 7 wird jeweils eine gebräuchliche Querschnittsform der Hohlkathode aufgeführt, nämlich ein runder und ein polygonaler Querschnitt.In claims 6 and 7, a common cross-sectional shape of the hollow cathode is listed, namely a round and a polygonal cross-section.
Anspruch 8 beschreibt einen möglichen Aufbau der Sputter-Hohlkathode. Das ist üblicherweise ein gut die Wärme leitender, mit Kühlmittel durchströmter Träger aus z.B. Kupfer, auf welchem die eigentliche Elektrode, die Sputter-Hohlkathode, mit gutem Wärmeübergang befestigt ist. Die Innenwand des z. B. rohrförmigen Hohlraums besteht entweder aus dem gewünschten Element, wovon die Strahlionen gewonnen werden sollen, oder ist damit beschichtet. Letztere Art der Elektroden-Herstellung kommt dann in Frage, wenn Ionenstrahlen von sehr teuren oder seltenen Elementen erzeugt werden sollen, wie z.B. angereicherte oder reine Isotope. Dabei wird von Fall zu Fall geprüft, ob das Aufbringen auf die Innenwand der Sputter -Hohlkathode auf galvanischem Wege oder per Drahtexplosion oder durch Aufdampfen oder durch Einklemmen eines dünnwandigen Röhrchens aus z.B. gerolltem Blech, erfolgen soll.Claim 8 describes a possible structure of the sputtering hollow cathode. This is usually a heat-conducting, coolant-flowing carrier made of, for example, copper, on which the actual electrode, the sputtering hollow cathode, is fastened with good heat transfer. The inner wall of the z. B. tubular cavity either consists of the desired element from which the radiation ions are to be obtained, or is coated with it. The latter type of electrode production can be used if ion beams are to be generated from very expensive or rare elements, such as enriched or pure ones Isotopes. It is checked on a case-by-case basis whether the application to the inner wall of the hollow sputter cathode should be by galvanic means or by wire explosion or by vapor deposition or by clamping a thin-walled tube made of, for example, rolled sheet metal.
Je nach Größe, Geometrie und Forderungen zu der Stärke des Magnetfelds der Anlage wird das Magnetfeld über einen Permanentmagneten (Anspruch 9) , einen Elektromagneten (Anspruch 10 oder über eine supraleitenden Magneten (Anspruch 11) erzeugt.Depending on the size, geometry and requirements for the strength of the magnetic field of the system, the magnetic field is generated via a permanent magnet (claim 9), an electromagnet (claim 10 or via a superconducting magnet (claim 11).
Das Material der Kanalwand muß neben guten Sputtereigenschaften auch gute Eigenschaften hinsichtlich der Sekundärelektronenemission aufweisen, zusätzlich muß es ausreichend thermisch belastbar sein.In addition to good sputtering properties, the material of the channel wall must also have good properties with regard to secondary electron emission;
Die Hohlkathoden-Sputter-Ionenquelle, zeichnet sich aus durch: i. die zur Hohlraumachse radiale Extraktion des Ionenstrahls aus der Sputter-Hohlkathode durch den achsparallelen Durchbruch hindurch, ii. die hohen Ionenstrahl-Intensitäten, siehe Tabelle der Ergebnisse unten, im Einzelimpuls bis zu Repetitionsraten um 100/sec, iii. die hohe Effizienz des Materialverbrauchs, ca. 2% gegenüber der Penning-Ionenquelle von nur ca. 0,02% iv. den im Vergleich zu klassischen Penning-Ionenquelle geringen Oszillationsanteil im Ionenstrahl-Signal, auch Hash oder Rauschen genannt.The hollow cathode sputter ion source is characterized by: i. the radial extraction of the ion beam from the hollow sputter cathode to the cavity axis through the axially parallel opening, ii. the high ion beam intensities, see table of results below, in the single pulse up to repetition rates around 100 / sec, iii. the high efficiency of material consumption, approx. 2% compared to the Penning ion source of only approx. 0.02% iv. the low oscillation component in the ion beam signal, also called hash or noise, in comparison to classic Penning ion sources.
Dadurch, dass die Ionen den Kathodenfall passieren und dabei in Vorwärtsrichtung beschleunigt werden, profitiert die Brillianz des Ionenstrahls. Vergleichende Messungen der Emittanz gleicher Ionenstrahlen aus der herkömmlichen Penning-Quelle und der neuen Ionenquelle am UNILAC, GSI-Darmstadt, bestätigen dies.The fact that the ions pass the cathode case and are accelerated in the forward direction benefits the brilliance of the ion beam. Comparative measurements of the emittance of the same ion beams from the conventional Penning source and the new ion source at UNILAC, GSI-Darmstadt, confirm this.
Die Sputter-Hohlkathoden Geometrie ist besonders für die Ökonomie und die Langzeitkonstanz des Ionenquellenbetriebs von Vor- teil . Die gesputterten neutralen Teilchen gelangen in das Plasma und werden dort durch schnelle Elektronen ionisiert und können nun, ebenfalls im Kathodenfall beschleunigt, entweder die Elektrode durch das Emissionsfenster verlassen oder durch „Selfsput- tering", oder auch durch „Sticking" an der Kanalwand den Io- nenproduktionsprozess unterstützen. Nicht ionisierte neutrale Teilchen treffen ebenfalls auf die Innenwand der Elektrode und sind somit weiter im Produktionsprozess präsent. Dies stellt einen beträchtlichen ökonomischen Vorteil dar gegenüber der herkömmlichen Sputter-Penningquelle, in welcher die meisten Teilchen, welche nicht als Ionen extrahiert werden, für weitere Ionenerzeugung verloren sind. Lediglich die neutralen Teilchen, welche den Innenzylinder der Sputter-Hohlkathode an den Zylinderenden und durch den Emissionsspalt verlassen, sind verloren. Ein weiterer kleiner Verlustbeitrag kommt von Ionen des gesputterten Materials, welche über den Kathodenfall in die Kathode/n implantiert werden.The sputtering hollow cathode geometry is particularly important for the economy and long-term constancy of ion source operation. part. The sputtered neutral particles get into the plasma and are ionized there by fast electrons. Now, also accelerated in the cathode case, they can either leave the electrode through the emission window or by "self-sputtering", or by "sticking" on the channel wall the Io - support the production process. Non-ionized neutral particles also hit the inner wall of the electrode and are therefore still present in the production process. This represents a significant economic advantage over the conventional sputtering Penning source in which most of the particles that are not extracted as ions are lost for further ion generation. Only the neutral particles that leave the inner cylinder of the sputtering hollow cathode at the cylinder ends and through the emission gap are lost. Another small loss contribution comes from ions of the sputtered material, which are implanted into the cathode (s) via the cathode case.
Die Erfindung wird im folgenden anhand der Zeichnungen mit denThe invention is based on the drawings with the
Figuren 1 bis 4 näher erläutert. Es zeigen:Figures 1 to 4 explained in more detail. Show it:
Figur 1 die Half-PIG-Konfiguration,FIG. 1 shows the half-PIG configuration,
Figur 2 die Full-PIG-Konfiguration,FIG. 2 shows the full PIG configuration,
Figur 3 das Prinzipschaltbild der Half-PIG-Konfiguration,FIG. 3 shows the basic circuit diagram of the half-PIG configuration,
Figur 4 das Prinzipschaltbild der Full-PIG-Konfiguration.Figure 4 shows the schematic diagram of the full PIG configuration.
Für die Realisation der Mechanik des Prototyps der neuen Ionenquelle wurde auf das modulare, mechanische Konzept der GSI- Penning-Ionenquelle zurückgegriffen. Dieses Konzept ist ein nicht publizierter GSI-interner Standard des Entwicklungsstandes vom Dezember 1989.The modular, mechanical concept of the GSI Penning ion source was used to implement the mechanics of the prototype of the new ion source. This concept is an unpublished GSI internal standard of the development status from December 1989.
Zu Figur 1 und Figur 3 (Half-PIG) :For Figure 1 and Figure 3 (Half-PIG):
Die obere Kathode der Ionenquelle ist indirekt beheizt. Auf der Achse nach unten hin folgt die intensiv gekühlte kurze Anode. An einer isolierten Durchführung mit gutem Wärmeübergang, ist die Elektrode der Sputter-Hohlkathode, die Antikathode, eingesetzt. Die folgende Anode ist in der Half-PIG-Version grundsätzlich nicht erforderlich ist aber für den gleichförmigen Gashaushalt der Entladung vorteilhaft.The upper cathode of the ion source is heated indirectly. The intensely cooled short anode follows on the axis downwards. The electrode of the sputtering hollow cathode, the anti-cathode, is used on an insulated bushing with good heat transfer. The following anode is basically in the half-PIG version is not necessary but is advantageous for the uniform gas balance of the discharge.
Der Stromkreis heiße Kathode-Anode wird über des Netzgerät NG1 gebildet. Die Hohlkathode ist galvanisch mit der heißen Kathode verbunden. Bezugspotential ist die Anode (plus). Das Potential ist für optimalen Betrieb, d.h. gute Ionenstrahl-Qualität und - Ausbeute einstellbar. Die Tastverhältnisse sind in weiten Grenzen einstellbar. Typisch für Hochstrom-Linearbeschleuniger als Injektoren für Synchrotrons sind Repetitionsraten von 1/s bis 10/s bei 0.5 ms bis 2 ms Pulslänge.The hot cathode anode circuit is formed via the power supply NG1. The hollow cathode is galvanically connected to the hot cathode. The reference potential is the anode (plus). The potential is for optimal operation, i.e. good ion beam quality and - yield adjustable. The duty cycle can be set within wide limits. Typical for high-current linear accelerators as injectors for synchrotrons are repetition rates from 1 / s to 10 / s with a pulse length of 0.5 ms to 2 ms.
Die nachstehenden Ergebnisse wurden für den Fall des homogenen magnetischen Feldes mit der Einstellung: 50/s und 1 ms, für den Fall des inhomogenen magnetischen Feldes mit der Einstellung: 10/s und 1 ms gewonnen.The following results were obtained for the case of the homogeneous magnetic field with the setting: 50 / s and 1 ms, for the case of the inhomogeneous magnetic field with the setting: 10 / s and 1 ms.
In Figur 1 ist die Half-PIG-Geometrie dargestellt, in welcher das asymmetrische Ionenquellen-Gebilde Half-PIG bei Betrieb nur einen Teil des Volumens des Hohlzylinders der Sputter-Hohlkathode nutzt. Für praktische Anwendung kann die Länge der Sputter-Hohlkathode den technischen Gegebenheiten angepasst werden. Der aus dem achsparallelen Schlitz oder Durchbruch in der Wand der Sputter-Hohlkathode extrahierte bandförmige Ionenstrahl positiv geladener Ionen, hat im wesentlichen die Breite der durch den Durchbruch sichtbaren Länge, hier 45mm, der Plasmasäule. Die Elektrodenkörper der Hohlkathode hat hier eine Länge von 60 mm, die Anodenlänge beträgt hier 18 mm, um die Kontur einer von vielen möglichen, maschinenspezifischen Geometrien aufzuzeigen.FIG. 1 shows the half-PIG geometry in which the asymmetrical ion source structure Half-PIG uses only a part of the volume of the hollow cylinder of the sputtering hollow cathode during operation. For practical use, the length of the hollow sputter cathode can be adapted to the technical circumstances. The band-shaped ion beam of positively charged ions extracted from the axially parallel slot or breakthrough in the wall of the sputtering hollow cathode has essentially the width of the length of the plasma column which is visible through the breakthrough, here 45 mm. The electrode body of the hollow cathode has a length of 60 mm, the anode length here is 18 mm to show the contour of one of many possible machine-specific geometries.
Figur 1 zeigt den Fall des Betriebs der Ionenquelle im inhomogenen Magnetfeld des Ionenquellenmagneten der Compact-PIG- Ionenquelle5' . Für den Fall des Betriebs der Ionenquelle im homogenen Magnetfeld spielt die Ausdehnung des Magnetfeldes für die Entladung keine Rolle, ist aber ionenoptisch für den Ionenstrahltransport bedeutungsvoll . Die Magnetfeldach.se liegt parallel zur Längsachse des Hohlzylin- ders der Sputter-Hohlkathode. Die Magnetfeldform ähnelt einer magnetischen Flasche mit dem Verhältnis der Kraftflußdichte:FIG. 1 shows the case of the operation of the ion source in the inhomogeneous magnetic field of the ion source magnet of the compact PIG ion source 5 '. In the case of operation of the ion source in a homogeneous magnetic field, the expansion of the magnetic field does not play a role in the discharge, but it is significant in terms of ion optics for the ion beam transport. The Magnetfeldach.se is parallel to the longitudinal axis of the hollow cylinder of the sputtering hollow cathode. The magnetic field shape is similar to a magnetic bottle with the ratio of the force flux density:
Flaschenhals : Flaschenbauch = 2 : 1,Bottle neck: bottle belly = 2: 1,
wobei die Kathoden (Full-PIG-Version s.u.) in den Flaschenhälsen angeordnet sind und die Sputter-Hohlkathode im Bereich des Flaschenbauchs installiert ist. Für die u.s. Meßwerte war die Magnetfeldachse mit der Längsachse des Hohlzylinders zusammengelegt. Beide Achsen können nach Bedarf zur Strahloptimierung zueinander parallel verschoben werden, was aber mit einigem technischen Aufwand verbunden ist.the cathodes (full PIG version see below) are arranged in the bottle necks and the sputtering hollow cathode is installed in the area of the bottle belly. For the u.s. Measured values, the magnetic field axis was merged with the longitudinal axis of the hollow cylinder. Both axes can be shifted parallel to each other as needed to optimize the beam, but this involves some technical effort.
Zu Fig. 2:2:
Die Geometrie in Figur 2 kann man sich durch Spiegelung der Half-PIG-Geometrie an einer senkrecht zur Achse der Sputter- Hohlkathode verlaufenden Ebene entstanden denken. Es entsteht das symmetrische Ionenquellengebilde Full-PIG, bestehend aus zwei Penning-Entladungsgeometrien welche, auf einer gemeinsamen Achse angeordnet, eine gemeinsame Antikathode nutzen.The geometry in FIG. 2 can be imagined by mirroring the half-PIG geometry on a plane running perpendicular to the axis of the sputtering hollow cathode. The result is the symmetrical ion source structure Full-PIG, consisting of two Penning discharge geometries, which, arranged on a common axis, use a common anti-cathode.
Die beiden Penning-Plasmen zusammen, im Volumen von der jeweiligen heißen Kathode / kalten Kathode ausgehend, bis zur Mitte des zylindrischen Hohlraums der Sputter-Hohlkathode als Antikathode reichend, da diese hier spiegelbildlich zur Mitteneben liegt, erfüllen den ganzen zylindrischen Zwischenraum zwischen den Kathoden, den beiden Anoden und in der Sputter-Hohlkathode.The two Penning plasmas together, starting in volume from the respective hot cathode / cold cathode, reaching as far as the center of the cylindrical cavity of the sputtering hollow cathode as an anti-cathode, since this is a mirror image of the center plane, fill the entire cylindrical space between the cathodes, the two anodes and in the sputtering hollow cathode.
Der aus der Sputter-Hohlkathode radial extrahierte, bandförmige Ionenstrahl positiver Ionen hat eine Breite, die der Länge des axialen Durchbruchs in der Sputter-Hohlkathode entspricht und ist der Elektrodenposition und Elektrodengeometrie entsprechend ebenfalls symmetrisch zur Mittenebene des Magnetfeldes und der Entladungsgeometrie . Beiden Konfigurationen, Half-PIG und Full-PIG, ist die radiale Extraktion eines Strahls positiv geladener Ionen in Form eines bandförmigen Strahls gemeinsam. Bei gleicher Spalt- bzw. Durchbruch-Geometrie in der Sputter-Hohlkathode unterscheiden sie sich in der Breite des Ionenstrahls und auch in der Intensität.The band-shaped ion beam of positive ions extracted radially from the hollow sputter cathode has a width which corresponds to the length of the axial opening in the hollow sputter cathode and is also symmetrical to the center position of the magnetic field and the discharge geometry in accordance with the electrode position and electrode geometry. Both configurations, half-PIG and full-PIG, have in common the radial extraction of a beam of positively charged ions in the form of a band-shaped beam. With the same gap or breakthrough geometry in the sputtering hollow cathode, they differ in the width of the ion beam and also in the intensity.
Unterschiedliche Magnetfeldstärken und -formen bedingen unterschiedliche Betriebsarten der Hohlkathoden-Sputter Ionenquelle. Höchste Ionenstrahlströme für niedrige Ladungszustände werden bislang im inhomogenen Magnetfeld erzielt.Different magnetic field strengths and shapes cause different operating modes of the hollow cathode sputter ion source. The highest ion beam currents for low charge states have so far been achieved in the inhomogeneous magnetic field.
Mit massiven Rohrelektroden aus z.B. Aluminium oder Molybdän als Sputter-Hohlkathoden werden in jeweils einem ununterbrochenen Betrieb bis zu 100 Stunden Strahlbetrieb mit hoher zeitlicher Stromkonstanz durchgeführt. Erste Abschätzungen des Materialverbrauchs zeigen Effizienzwerte um 2% im Gegensatz zu Penning- Ionenquellen von ca. 0,02%. With solid tubular electrodes made of, for example, aluminum or molybdenum as hollow sputtering cathodes, up to 100 hours of blasting operation are carried out in one continuous operation with a high level of current consistency. Initial estimates of material consumption show efficiency values of around 2% compared to Penning ion sources of around 0.02%.
Tabelle der Ergebnisse mit der Full-PIG Version in unterschiedlichen MagnetfeldernTable of results with the full PIG version in different magnetic fields
FULL-PIG : Ergebnisse , homogenes Magnetfeld (OLDPIG)FULL-PIG: Results, homogeneous magnetic field (OLDPIG)
ION Ladung Masse Are U Are I Magnetfeld lonenstrom Extraction Periode Pulslange ARC PowerION charge mass Are U Are I magnetic field ion current extraction period pulse length ARC power
Amu Volt Amp Tesla mA kV ms ms WattsAmu Volt Amp Tesla mA kV ms ms Watts
AI 1 27 1200 4 0,6 16 15 20 1,3 312AI 1 27 1200 4 0.6 16 15 20 1.3 312
Ti 1 48 500 6 0,77 6 13,5 20 1 150Ti 1 48 500 6 0.77 6 13.5 20 1 150
Ti 2 48 2400 6 0,53 8 12,95 40 2 720Ti 2 48 2400 6 0.53 8 12.95 40 2 720
Ni 1 58 1100 7,5 0,75 5 10,7 20 OJ 289Ni 1 58 1100 7.5 0.75 5 10.7 20 OJ 289
Cu 1 63 1500 16 0,86 12 12,8 100 1 ,5 360Cu 1 63 1500 16 0.86 12 12.8 100 1, 5 360
FULL-PIG : Ergebnisse, inhomogenes Magnetfeld (CPIG)FULL-PIG: results, inhomogeneous magnetic field (CPIG)
ION Ladung Masse Are U Arc l Magnetfeld lonenstrom Extraction Periode Pulslänge ARC Power amu Volt Amp Tesla mA kV ms ms Watts cwION charge mass Are U Arc l magnetic field ion current extraction period pulse length ARC Power amu Volt Amp Tesla mA kV ms ms Watts cw
AI 1 27 550 5,5 0,15 14 12,4 200 1 15AI 1 27 550 5.5 0.15 14 12.4 200 1 15
AI 1 27 750 16 0,15 45 23,23 100 1 120AI 1 27 750 16 0.15 45 23.23 100 1 120
Al- 2 27 800 15,5 0,15 3,5 22,74 100 1 124Al- 2 27 800 15.5 0.15 3.5 22.74 100 1 124
Ti 1 48 1000 22 0,15 24 24,88 100 0,8 176Ti 1 48 1000 22 0.15 24 24.88 100 0.8 176
Ti 2 48 600 23,5 0,15 15 24,24 100 1 141Ti 2 48 600 23.5 0.15 15 24.24 100 1 141
Ti 3 48 600 23 0,15 2,2 24,88 100 0,8 110Ti 3 48 600 23 0.15 2.2 24.88 100 0.8 110
Ni 1 58 900 12 0,15 11 19,4 100 1,5 162Ni 1 58 900 12 0.15 11 19.4 100 1.5 162
Cu 1 63 1000 3,5 0,14 16 17,4 100 1 35Cu 1 63 1000 3.5 0.14 16 17.4 100 1 35
Cu 2 63 750 3,3 0,14 1,3 16,3 200 2 25Cu 2 63 750 3.3 0.14 1.3 16.3 200 2 25
Mo 1 98 900 8 0,15 1,6 10,3 100 1 72Mo 1 98 900 8 0.15 1.6 10.3 100 1 72
Mo 2 98 500 15 0,15 10 21 ,8 100 0,75 56Mo 2 98 500 15 0.15 10 21, 8 100 0.75 56
Mo 3 98 500 15 0,15 2 21,8 100 0,75 56Mo 3 98 500 15 0.15 2 21.8 100 0.75 56
Mo 4 98 400 6,5 0,15 0,122 19,67 100 2 52Mo 4 98 400 6.5 0.15 0.122 19.67 100 2 52
Pb 1 208 200 4,4 0,14 1 5,9 40 1 22Pb 1 208 200 4.4 0.14 1 5.9 40 1 22
Pb 2 208 200 4,4 0,15 2 10,7 200 1 4Pb 2 208 200 4.4 0.15 2 10.7 200 1 4
Legende:Legend:
ARC U : EntladungsspannungARC U: discharge voltage
ARC I : EntladungsstromARC I: discharge current
Magnetfeld: Kraftflussdichte des Magnetfeldes der Ionenquelle lonenstrom: Pulsamplitude des Ionenstrahlstroms nach AnalyseMagnetic field: force flux density of the magnetic field of the ion source ion current: pulse amplitude of the ion beam current after analysis
Extraction: Potential der Ionenquelle gegen ErdpotentialExtraction: potential of the ion source against earth potential
Periode: Periode der EntladungspulsfolgePeriod: Period of the discharge pulse train
Pulslänge: zeitliche Dauer des EntladungspulsesPulse length: duration of the discharge pulse
ARC Power: mittlere Entladungsleistung Literatur :ARC Power: medium discharge power Literature:
1) "Handbook of Ion Sources" by Bernhard Wolf,1) "Handbook of Ion Sources" by Bernhard Wolf,
GSI Center for Heavy Ion Research Darmstadt, Germany, Crc Press Boca Raton New York London Tokyo, 1995, P 69) .GSI Center for Heavy Ion Research Darmstadt, Germany, Crc Press Boca Raton New York London Tokyo, 1995, P 69).
2) P.M. Morozow et. al . , Atomnaya Energiya2 PM. Morozow et. al. , Atomnaya Energiya
3, 272, (1957)3, 272, (1957)
3) M. Müller und G. Hortig , IEEE Trans. Nucl. Sei NS-16, 38, 19693) M. Müller and G. Hortig, IEEE Trans. Nucl. Be NS-16, 38, 1969
4) H. Winter, GSI - Bericht PB1-74, Darmstadt 19744) H. Winter, GSI report PB1-74, Darmstadt 1974
5) M. Müller, IEEE Trans. Nucl. Sei. NS-30 (1983) 1499 5) M. Müller, IEEE Trans. Nucl. Be. NS-30 (1983) 1499

Claims

Patentansprüche : Claims:
1. Hohlkathoden-Sputter-Ionenquelle zur Erzeugung von Ionenstrahlen hoher Intensität, mittlerer Ladung bei niedriger Energie, bestehend aus: einem Elektromagneten zur Erzeugung eines rotationssymmetrischen Magnetfelds, einer extern beheizbaren Kathode, die heiße Kathode, die mit ihrem elektrisch wirksamen Bereich auf der Achse des Magnetfelds in demselben liegt, . einer mit Kühlmittel durchströmten Antikathode, der kalten Kathode, einer Penning-Entladung mit zylindrischem Hohlraum, das ist die Sputter-Hohlkathode oder Sputter- Antikathode, wobei der Hohlraum mit seiner Hohlraumlängsachse auf der oder parallel zu der Magnetfeldachse liegt und die Wand des Hohlraums aus dem sputterbarem Material des zu erzeugenden Ionenstrahls besteht oder dessen Innenwand mit diesem Material beschichtet ist, und die in ihrer Wand einen achsparallelen, schlitzförmigen Durchbruch hat,1.Hollow cathode sputter ion source for generating ion beams of high intensity, medium charge at low energy, consisting of: an electromagnet for generating a rotationally symmetrical magnetic field, an externally heated cathode, the hot cathode, with its electrically effective area on the axis of the Magnetic field lies in the same,. an anti-cathode through which coolant flows, the cold cathode, a Penning discharge with a cylindrical cavity, that is the sputtering hollow cathode or sputtering anti-cathode, the cavity lying with its longitudinal axis on or parallel to the magnetic field axis and the wall of the cavity from the sputterable material of the ion beam to be generated or whose inner wall is coated with this material and which has an axially parallel, slot-shaped opening in its wall,
- einer mit Kühlmittel durchströmten Anode, zur Erzeugung eines Penning-Plasmas, das an der Kathode beginnt und in den Hohlraum der Sputter-Hohlkathode, welche die Antikathode der Penning-Entladung ist, hineinreicht, woraus die Ionen aus dem Innenwandmaterial durch den Durchbruch hindurch radial zur Hohlraumlängsachse extrahiert werden.an anode through which coolant flows, for generating a Penning plasma, which begins at the cathode and extends into the cavity of the sputtering hollow cathode, which is the anti-cathode of the Penning discharge, from which the ions from the inner wall material radially through the opening be extracted to the longitudinal axis of the cavity.
2. Hohlkathoden-Sputter-Ionenquelle zur Erzeugung von Ionenstrahlen hoher Intensität, mittlerer Ladung bei niedriger Energie, bestehend aus:2. Hollow cathode sputter ion source for generating ion beams of high intensity, medium charge at low energy, consisting of:
- einem Magneten zur Erzeugung eines rotationssymmetrischen Magnetfelds,a magnet for generating a rotationally symmetrical magnetic field,
- zwei Kathoden, wovon zumindest eine extern beheizt ist, die mit ihrem elektrisch wirksamen Bereich auf der Achse des Magnetfelds in demselben liegen und dies- und jen- seits der Mittenebene des Magnetfelds senkrecht durch die Magnetfeldachse positioniert sind, einer mit Kühlmittel durchströmten Antikathode mit zylindrischem Hohlraum, der Sputter-Hohlkathode, die zwischen den beiden Kathoden und zugehörigen Anoden mit ihrer Hohlraumlängsachse auf der oder parallel zu der Magnetfeldachse liegt, deren Wand aus dem Material des zu erzeugenden Ionenstrahls besteht oder deren Innenwand mit diesem Material beschichtet ist und die in ihrer Wand einen achsparallelen, schlitzförmigen Durchbruch hat, zwei mit Kühlmittel durchströmten Anoden, zur Erzeugung zweier in den Hohlraum der Sputter-Hohlkathode hineinreichender Penning-Plasmen, die jeweils an der zugehörigen Kathode beginnen und in den Hohlraum der Sputter- Hohlkathode, die die gemeinsame Antikathode der beiden Penning-Entladungen ist, hineinreichen, woraus die Ionen aus dem Innenwandmaterial durch den Durchbruch hindurch radial zur Hohlraumlängsachse extrahiert werden.two cathodes, of which at least one is heated externally, with their electrically active area lying on the axis of the magnetic field in the same and this and that are positioned perpendicular to the center plane of the magnetic field through the magnetic field axis, an anti-cathode with a cylindrical cavity through which coolant flows, the sputtering hollow cathode, which lies between the two cathodes and associated anodes with their longitudinal axis along or parallel to the magnetic field axis, the wall of which extends from the Material of the ion beam to be generated or the inner wall of which is coated with this material and which has an axially parallel, slot-shaped opening in its wall, two anodes through which coolant flows, for generating two Penning plasmas reaching into the cavity of the sputtering hollow cathode, each on begin with the associated cathode and extend into the cavity of the sputtering hollow cathode, which is the common anti-cathode of the two Penning discharges, from which the ions are extracted from the inner wall material through the opening radially to the longitudinal axis of the cavity.
3. Hohlkathoden-Sputter-Ionenquelle nach Anspruch 2, dadurch gekennzeichnet, dass die beiden Kathoden spiegelbildlich zur Mittenebene des Hohlraums der Sputter-Hohlkathode, die die Richtung der Hohlraum¬ achse hat, liegen.3. hollow cathode sputter ion source according to claim 2, characterized in that the two cathode to the center plane of the cavity of the hollow cathode sputtering having the direction of the cavity ¬ axis are mirror images.
4. Hohlkathoden-Sputter-Ionenquelle nach den Ansprüchen 1 und 3, dadurch gekennzeichnet, dass die Sputter-Antikathode an eine eigene unabhängig triggerbare und einstellbare Stromquelle (NG2) angeschlossen ist.4. Hollow cathode sputtering ion source according to claims 1 and 3, characterized in that the sputtering anti-cathode is connected to its own independently triggerable and adjustable current source (NG2).
5. Hohlkathoden-Sputter-Ionenquelle nach Anspruch 4, dadurch gekennzeichnet, dass die heiße Kathode bzw. beiden heißen Kathoden an eine eigene unabhängig triggerbare und einstellbare Stromquelle (NGl) angeschlossen ist bzw. sind. 5. Hollow cathode sputter ion source according to claim 4, characterized in that the hot cathode or both hot cathodes are or are connected to their own independently triggerable and adjustable current source (NGl).
6. Hohlkathoden-Sputter-Ionenquelle nach Anspruch 5, dadurch gekennzeichnet, dass der Hohlraum der Sputter-Antikathode einen kreisförmigen Querschnitt hat.6. Hollow cathode sputtering ion source according to claim 5, characterized in that the cavity of the sputtering anti-cathode has a circular cross section.
7. Hohlkathoden-Sputter-Ionenquelle nach Anspruch 5, dadurch gekennzeichnet, dass der Hohlraum der Sputter-Antikathode einen polygonalen Querschnitt hat.7. Hollow cathode sputtering ion source according to claim 5, characterized in that the cavity of the sputtering anti-cathode has a polygonal cross section.
8. Hohlkathoden-Sputter-Ionenquelle nach den Ansprüchen 6 und 7, dadurch gekennzeichnet, dass die Sputter-Hohlkathode aus einem gut die Wärme leitenden, metallischen Trägermaterial, wie Edelstahl oder Kupfer, besteht und deren Innenwand mit dem Material der zu erzeugenden Ionen beschichtet ist.8. Hollow cathode sputtering ion source according to claims 6 and 7, characterized in that the sputtering hollow cathode consists of a good heat-conducting, metallic carrier material, such as stainless steel or copper, and the inner wall of which is coated with the material of the ions to be generated ,
9. Hohlkathoden-Sputter-Ionenquelle nach Anspruch 8, dadurch gekennzeichnet, dass der Magnet ein Permanentmagnet ist.9. hollow cathode sputter ion source according to claim 8, characterized in that the magnet is a permanent magnet.
10. Hohlkathoden-Sputter-Ionenquelle nach Anspruch 8, dadurch gekennzeichnet, dass der Magnet ein Elektromagnet ist.10. Hollow cathode sputter ion source according to claim 8, characterized in that the magnet is an electromagnet.
11. Hohlkathoden-Sputter-Ionenquelle nach Anspruch 8, dadurch gekennzeichnet, dass der Magnet ein supraleitender Magnet ist. 11. Hollow cathode sputter ion source according to claim 8, characterized in that the magnet is a superconducting magnet.
PCT/EP2001/000996 2000-03-04 2001-01-31 Hollow cathode sputter ion source for generating high-intensity ion beams WO2001067482A1 (en)

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CN102497717A (en) * 2011-11-25 2012-06-13 北京大学 Magnet used for plasma device and plasma device

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DE102008022145B4 (en) * 2008-05-05 2015-03-12 Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. Apparatus and method for high performance pulse-gas flow sputtering
DE102016119791A1 (en) * 2016-10-18 2018-04-19 scia Systems GmbH Method and device for processing a surface of a substrate by means of a particle beam

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CN102497717A (en) * 2011-11-25 2012-06-13 北京大学 Magnet used for plasma device and plasma device
CN102497721A (en) * 2011-11-29 2012-06-13 北京大学 Plasma device with double-hollow cathode and double-hollow cathode and applications

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