WO2001067482A1 - Source ionique de pulverisation a cathode creuse permettant d'obtenir des faisceaux ioniques d'intensite elevee - Google Patents

Source ionique de pulverisation a cathode creuse permettant d'obtenir des faisceaux ioniques d'intensite elevee 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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WO
WIPO (PCT)
Prior art keywords
cathode
sputtering
hollow cathode
ion source
cavity
Prior art date
Application number
PCT/EP2001/000996
Other languages
German (de)
English (en)
Inventor
Michael Müller
Original Assignee
Gesellschaft für Schwerionenforschung mbH
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Gesellschaft für Schwerionenforschung mbH filed Critical Gesellschaft für Schwerionenforschung mbH
Priority to EP01909713A priority Critical patent/EP1261982A1/fr
Priority to AU2001237357A priority patent/AU2001237357A1/en
Publication of WO2001067482A1 publication Critical patent/WO2001067482A1/fr

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Classifications

    • 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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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Combustion & Propulsion (AREA)
  • Analytical Chemistry (AREA)
  • Electron Sources, Ion Sources (AREA)

Abstract

La présente invention concerne une géométrie de cathode de pulvérisation creuse qui présente des avantages particuliers en ce qui concerne l'économie et la régularité à long terme du fonctionnement de la source ionique. Les particules neutres pulvérisées arrivent dans le plasma et y sont ionisées par des électrons à vitesse élevée, lesdites particules pouvant alors, même lorsqu'elles sont accélérées en cas de chute cathodique, soit quitter l'électrode par la fenêtre d'émission, soit entretenir le processus de production ionique par 'auto-pulvérisation' ou par 'adhérence' à la paroi de canal. Les particules neutres non ionisées se retrouvent également sur la paroi interne de l'électrode et restent ainsi présentes pour le processus de production. Ceci représente un avantage économique vis-à-vis de la source de pulvérisation de Penning dans laquelle la plupart des particules qui ne sortent pas sous forme d'ions, sont perdues pour la suite du processus de production d'ions.
PCT/EP2001/000996 2000-03-04 2001-01-31 Source ionique de pulverisation a cathode creuse permettant d'obtenir des faisceaux ioniques d'intensite elevee WO2001067482A1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
EP01909713A EP1261982A1 (fr) 2000-03-04 2001-01-31 Source ionique de pulverisation a cathode creuse permettant d'obtenir des faisceaux ioniques d'intensite elevee
AU2001237357A AU2001237357A1 (en) 2000-03-04 2001-01-31 Hollow cathode sputter ion source for generating high-intensity ion beams

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE10010706.0 2000-03-04
DE2000110706 DE10010706C2 (de) 2000-03-04 2000-03-04 Hohlkathoden-Sputter-Ionenquelle zur Erzeugung von Ionenstrahlen hoher Intensität

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Publication Number Publication Date
WO2001067482A1 true WO2001067482A1 (fr) 2001-09-13

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Country Status (4)

Country Link
EP (1) EP1261982A1 (fr)
AU (1) AU2001237357A1 (fr)
DE (1) DE10010706C2 (fr)
WO (1) WO2001067482A1 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102497721A (zh) * 2011-11-29 2012-06-13 北京大学 双空心阴极以及双空心阴极等离子体装置和应用
CN102497717A (zh) * 2011-11-25 2012-06-13 北京大学 一种用于等离子体装置的磁铁及等离子体装置

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE10306936B3 (de) * 2003-02-19 2004-06-24 Gesellschaft für Schwerionenforschung mbH Multi-Mode-Metall-Ionenquelle mit der Struktur einer Hohlkathoden-Sputter-Ionenquelle mit radialer Ionenextraktion
DE102008022145B4 (de) * 2008-05-05 2015-03-12 Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. Vorrichtung und Verfahren zum Hochleistungs-Puls-Gasfluß-Sputtern
DE102016119791A1 (de) * 2016-10-18 2018-04-19 scia Systems GmbH Verfahren und Vorrichtung zum Bearbeiten einer Oberfläche eines Substrates mittels eines Teilchenstrahls

Citations (1)

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Publication number Priority date Publication date Assignee Title
JPH0696680A (ja) * 1991-04-18 1994-04-08 Ulvac Japan Ltd 金属イオン源

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US3566185A (en) * 1969-03-12 1971-02-23 Atomic Energy Commission Sputter-type penning discharge for metallic ions
US4344019A (en) * 1980-11-10 1982-08-10 The United States Of America As Represented By The United States Department Of Energy Penning discharge ion source with self-cleaning aperture

Patent Citations (1)

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Publication number Priority date Publication date Assignee Title
JPH0696680A (ja) * 1991-04-18 1994-04-08 Ulvac Japan Ltd 金属イオン源

Non-Patent Citations (4)

* Cited by examiner, † Cited by third party
Title
AKIRA TONEGAWA ET AL: "DOUBLE HOLLOW CATHODE ION SOURCE FOR METAL ION-BEAM PRODUCTION", NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH, SECTION - B: BEAM INTERACTIONS WITH MATERIALS AND ATOMS,NL,NORTH-HOLLAND PUBLISHING COMPANY. AMSTERDAM, vol. B55, no. 1 / 04, 2 April 1991 (1991-04-02), pages 331 - 334, XP000230698, ISSN: 0168-583X *
MOROZOW P.M. ET AL.: "Istochnik miogozariyadnikh ionov azota dliya tsiklotrona", ATOMNAYA ENERGIYA, vol. 3, no. 275, 1957, pages 272, XP001004860 *
PATENT ABSTRACTS OF JAPAN vol. 018, no. 355 (E - 1573) 5 July 1994 (1994-07-05) *
See also references of EP1261982A1 *

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102497717A (zh) * 2011-11-25 2012-06-13 北京大学 一种用于等离子体装置的磁铁及等离子体装置
CN102497721A (zh) * 2011-11-29 2012-06-13 北京大学 双空心阴极以及双空心阴极等离子体装置和应用

Also Published As

Publication number Publication date
DE10010706A1 (de) 2001-09-13
AU2001237357A1 (en) 2001-09-17
EP1261982A1 (fr) 2002-12-04
DE10010706C2 (de) 2002-07-25

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