EP1052668A1 - Betrieb bei Hochdruck einer Feldemissionskaltkathode - Google Patents

Betrieb bei Hochdruck einer Feldemissionskaltkathode Download PDF

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Publication number
EP1052668A1
EP1052668A1 EP00401027A EP00401027A EP1052668A1 EP 1052668 A1 EP1052668 A1 EP 1052668A1 EP 00401027 A EP00401027 A EP 00401027A EP 00401027 A EP00401027 A EP 00401027A EP 1052668 A1 EP1052668 A1 EP 1052668A1
Authority
EP
European Patent Office
Prior art keywords
microtips
electrons
emission
heating means
anode
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.)
Withdrawn
Application number
EP00401027A
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English (en)
French (fr)
Inventor
Didier Pierrejean
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.)
Alcatel CIT SA
Alcatel Lucent SAS
Original Assignee
Alcatel CIT SA
Alcatel SA
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 Alcatel CIT SA, Alcatel SA filed Critical Alcatel CIT SA
Publication of EP1052668A1 publication Critical patent/EP1052668A1/de
Withdrawn legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J3/00—Details of electron-optical or ion-optical arrangements or of ion traps common to two or more basic types of discharge tubes or lamps
    • H01J3/02—Electron guns
    • H01J3/021—Electron guns using a field emission, photo emission, or secondary emission electron source
    • H01J3/022—Electron guns using a field emission, photo emission, or secondary emission electron source with microengineered cathode, e.g. Spindt-type
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J1/00—Details of electrodes, of magnetic control means, of screens, or of the mounting or spacing thereof, common to two or more basic types of discharge tubes or lamps
    • H01J1/02—Main electrodes
    • H01J1/13—Solid thermionic cathodes
    • H01J1/20—Cathodes heated indirectly by an electric current; Cathodes heated by electron or ion bombardment
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J1/00—Details of electrodes, of magnetic control means, of screens, or of the mounting or spacing thereof, common to two or more basic types of discharge tubes or lamps
    • H01J1/02—Main electrodes
    • H01J1/30—Cold cathodes, e.g. field-emissive cathode
    • H01J1/304—Field-emissive cathodes
    • H01J1/3042—Field-emissive cathodes microengineered, e.g. Spindt-type
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J2201/00—Electrodes common to discharge tubes
    • H01J2201/19—Thermionic cathodes
    • H01J2201/196—Emission assisted by other physical processes, e.g. field- or photo emission
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J2201/00—Electrodes common to discharge tubes
    • H01J2201/30—Cold cathodes
    • H01J2201/304—Field emission cathodes
    • H01J2201/30403—Field emission cathodes characterised by the emitter shape

Definitions

  • the present invention relates to methods or devices detection or measurement of gases in which a flow is generated of electrons in a vacuum chamber from a cathode to field emission including a network of transmitting microdots of electrons associated with a grid.
  • the electrons are sent in an ionization cage in the presence of the gas to be analyzed and generate a ion flow which is then analyzed by a processing device such as a mass spectrometer.
  • microtip field emission cathodes electron emitters, in which microtips electrically conductive are made on a substrate suitable conductor and embedded in cavities of a layer insulating covering the substrate, with their ends coming in outcrop of a positively polarized grid comprising openings with regard to each cavity.
  • the sharp shape of the peaks microtips produces a local field amplification effect electric which promotes the emission of electrons at temperature ambient and allows this emission to be obtained from a voltage threshold in the range of 50 to 100 volts depending on the constitution of the microtip network.
  • a mass spectrometer associated with a cold cathode with field emission with microtips is described in document EP 0 884 762 A.
  • a second cathode having a thermal emission filament improves the analysis of gas by having two spectra to resolve ambiguities.
  • field emission cathodes or cathodes cold, have substantial advantages over traditional sources constituted by a tungsten filament heated to a temperature of 1,000 to 2,000 ° C.
  • field emission cathodes have a very good energy efficiency, by the fact that the microtips allow emitting electrons from temperature ambient, while the tungsten filaments require a significant heating electrical energy to bring the filament at a temperature allowing the emission of electrons by thermoelectronic effect; the orders of magnitude of the powers about 10 watts are used for a heated filament, at compare to about 0.2 watts for a field emission cathode.
  • Field emission cathodes also have the advantage of a rapid reaction, both at the start emission only at the end of electron emission; it is thus possible to deactivate them instantly, unlike a filament of tungsten with temperature and emissive properties due to its inertia only fall slowly thermal.
  • Field emission cathodes also have the advantage of generating a directive electron beam, every electrons being emitted perpendicular to the surface of the lattice microtips, unlike a filament for which electrons are emitted in all directions around the filament.
  • Another advantage is the absence of heat dissipation field emission cathodes, avoiding disturbing circuits surrounding electronics that are sensitive to temperature.
  • Field emission cathodes work properly when the residual gas pressure inside the vacuum enclosure is less than about 10 -5 hPa.
  • achieving and maintaining a sufficiently low residual pressure in the vacuum enclosure requires appropriate pumping means, and above all a sufficiently long pumping time. This is a drawback in applications for the analysis or detection of gases, in which the electron generation device is used in an enclosure where an intermittent vacuum is produced: it is necessary to wait for the obtaining of the sufficient vacuum before proceeding with analysis or measurement.
  • the problem proposed by the present invention is to devise a means of reducing the risk of breakdown of field emission cathodes used in devices gas detection or measurement, for a given network geometry of microtips and for a given flux of emitted electrons.
  • the present invention results from the surprising observation according to which the risks of breakdown, with constant flow of electrons emitted, decrease significantly when the microtips of the field emission cathode.
  • the present invention takes advantage of this observation to solve the problem of breakdown of field emission cathodes working at pressures higher than 10 -5 hPa, by proposing a device for detecting or measuring gas, comprising a vacuum enclosure. containing an ionization cage anode for generating an ion output stream, a processing device for discriminating and measuring ions in the ion output stream, and a field emission cathode with an emitting microtip array of electrons associated with a grid and generating an input flux of electrons into the anode, and comprising heating means for bringing and maintaining the microtips at a temperature above ambient temperature during the emission of electrons.
  • the heating means can advantageously be adapted to bring and maintain the microtips at a temperature higher than approximately 300 ° C during the emission of electrons.
  • the microtips are carried by a substrate incorporating the heating means.
  • the heating means are elements electrically resistive housed in the substrate near the microtips and connectable to a source of electrical energy.
  • Such an electron generation device can operate with a field emission cathode housed in a vacuum enclosure where there is a residual gas pressure greater than 10 -5 hPa.
  • the processing device can for example be a mass spectrometer.
  • the increase in the temperature of the microtips at a temperature of between 300 ° C. and 400 ° C. approximately, made it possible to keep the same flow of electrons with a lower bias voltage, avoiding the breakdown of the cathode. It was thus possible to reach, with the same geometry of field emission cathode, a residual gas pressure of 10 -4 hPa in the vacuum enclosure.
  • the invention provides a method of detecting or gas measurement, using a vacuum enclosure containing an anode forming an ionization cage to generate an ion output flux, a processing device for discrimination and measurement of ions from the ion output stream, and a field emission cathode to network of electron-emitting microdots associated with a grid and generating an electron input flux in the anode, and in which the microtips are brought to a temperature above room temperature, preferably above 300 ° C, for example between 300 ° C and 400 ° C approximately.
  • an emission cathode field 1 comprises a ceramic support 2 carrying a substrate 3, by example in silicon or other suitable material and conductor of electricity.
  • the active face 30 of the substrate 3 carries a network of microtips such as microtips 4 to 7, housed in corresponding cavities 8 to 11 provided in an insulating layer 12, for example made of silicon oxide, the outer face of which is covered with a conductive material forming a grid 13 pierced with right of the cavities 8 to 11.
  • the tips of the microtips 4-7 come flush with the grid surface 13.
  • the size of the cavities 8 to 11, and therefore the size of the microtips 4 to 7, is of the order of a micron in height and in width.
  • Micropoint arrays are generally produced, the density of which is of the order of 10,000 to 100,000 microtips per mm 2 .
  • the cathode to field emission 1 is housed in a vacuum chamber 14, and one again distinguishes the support 2, the substrate 3 and the grid 13.
  • the grid 13 is positively polarized with respect to substrate 3 by an electric gate bias generator 15.
  • Field emission cathode 1 is associated with an anode 16 in the form of a box with walls made of non-magnetic material forming a cage of Faraday and constituting an ionization cage.
  • Anode 16 includes an entrance slot 17 for the penetration of electrons from the field emission cathode 1, and a light 18 for extracting the ions formed in the interior cavity of the anode 16.
  • the arrow 19 represents the flow of electrons entering the anode 16, and the arrow 20 illustrates the output flow of the ions out of anode 16.
  • the ion output stream 20 is sent to a processing device 21, schematically represented, comprising means for discriminating and measuring the ions contained in the ion output stream 20, for example a mass spectrometer.
  • Anode 16 is positively polarized with respect to the grid 13 by an electric anode bias generator 22.
  • the vacuum enclosure 14 is formed by a peripheral wall sealed having an extraction outlet 23 connected to a vacuum pump, and an inlet 24 through which a gas to be analyzed is penetrated.
  • the device illustrated in FIG. 1 constitutes an apparatus gas detection or measurement.
  • the electron flow 19 depends both on the voltage of grid polarization ensured by the electric generator of grid polarization 15, and residual gas pressure present in the interior of the vacuum chamber 14.
  • the invention makes it possible to increase the residual gas pressure inside the vacuum vessel 14, thereby reducing the risk of cathode breakdown at field emission 1, and increasing its lifespan, or allowing operation at higher residual pressures.
  • enclosure 14 Under the usual conditions of use, it can reign in enclosure 14 an intermittent vacuum, that is to say a Sufficient vacuum sequence for the operation of the means of gas analysis or measurement, and more pressure steps high for example for the introduction of an object to be tested or for connection to a container of the gas to be analyzed.
  • the invention makes it possible to speed up analyzes or measurements, by authorizing the correct and reliable operation without waiting for a vacuum pushed is reached in the vacuum chamber 14.
  • FIG. 2 shows an embodiment particular heating means making it possible to bring and maintain microtips 4 to 7 at an appropriate temperature during the emission of electrons.
  • these heating means are electrically resistive elements 25, 26, 27 and 28 insulated electrically and housed in the substrate 3 near the microtips 4 to 7, and connectable to an energy source electric.
  • the heating means can be electrically resistive elements housed in the support 2 of the substrate 3 and connectable to a source of electrical energy.
  • the source of electrical energy can be a generator of separate heating current 29 illustrated in FIG. 2.
  • the electric power source can be used electric gate bias generator 15, at the terminals from which the elements are directly connected electrically resistive 25-28.

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  • Other Investigation Or Analysis Of Materials By Electrical Means (AREA)
  • Cold Cathode And The Manufacture (AREA)
  • Electron Tubes For Measurement (AREA)
EP00401027A 1999-04-22 2000-04-13 Betrieb bei Hochdruck einer Feldemissionskaltkathode Withdrawn EP1052668A1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR9905089A FR2792770A1 (fr) 1999-04-22 1999-04-22 Fonctionnement a haute pression d'une cathode froide a emission de champ
FR9905089 1999-04-22

Publications (1)

Publication Number Publication Date
EP1052668A1 true EP1052668A1 (de) 2000-11-15

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Family Applications (1)

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EP00401027A Withdrawn EP1052668A1 (de) 1999-04-22 2000-04-13 Betrieb bei Hochdruck einer Feldemissionskaltkathode

Country Status (4)

Country Link
US (1) US6559442B1 (de)
EP (1) EP1052668A1 (de)
JP (1) JP2000353492A (de)
FR (1) FR2792770A1 (de)

Families Citing this family (4)

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Publication number Priority date Publication date Assignee Title
US20060185595A1 (en) * 2005-02-23 2006-08-24 Coll Bernard F Apparatus and process for carbon nanotube growth
CH698896B1 (de) * 2006-08-29 2009-11-30 Inficon Gmbh Massenspektrometer.
JP5579038B2 (ja) * 2010-05-14 2014-08-27 キヤノンアネルバ株式会社 冷陰極電離真空計、該冷陰極電離真空計を備えた真空処理装置、該冷陰極電離真空計に用いる放電開始補助電極、該冷陰極電離真空計を用いた圧力測定方法
GB2518122B (en) * 2013-02-19 2018-08-08 Markes International Ltd An electron ionisation apparatus

Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1520972A (fr) * 1966-04-30 1968-04-12 Beteiligungs & Patentverw Gmbh Source d'ions à émission par champ
DE2212424A1 (de) * 1971-03-25 1972-09-28 Cambridge Scientific Instr Ltd Elektronenkanone
US3786305A (en) * 1972-05-15 1974-01-15 Hitachi Ltd Field emission electron gun
US3786268A (en) * 1971-04-12 1974-01-15 Hitachi Ltd Electron gun device of field emission type
US3887835A (en) * 1972-06-09 1975-06-03 Hitachi Ltd Field emission electron gun
EP0601533A1 (de) * 1992-12-07 1994-06-15 Ricoh Company, Ltd Mikrovakuumvorrichtung
JPH0765696A (ja) * 1993-08-30 1995-03-10 Canon Inc 電子放出素子
FR2714208A1 (fr) * 1993-12-22 1995-06-23 Mitsubishi Electric Corp Cathode, canon à électrons comportant une telle cathode et tube à rayons cathodiques comportant un tel canon.
JPH09283065A (ja) * 1996-04-16 1997-10-31 Futaba Corp 電界放出型表示素子およびその駆動方法
EP0884762A1 (de) * 1997-06-13 1998-12-16 Commissariat A L'energie Atomique Spektrometer mit zwei verschiedenen Ionisationsvorrichtungen und Datenverarbeitungsverfahren dafür

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JP2607251B2 (ja) * 1987-08-26 1997-05-07 松下電工株式会社 電界放射陰極
US5386115A (en) * 1993-09-22 1995-01-31 Westinghouse Electric Corporation Solid state micro-machined mass spectrograph universal gas detection sensor
US5747815A (en) * 1993-09-22 1998-05-05 Northrop Grumman Corporation Micro-miniature ionizer for gas sensor applications and method of making micro-miniature ionizer
US6175120B1 (en) * 1998-05-08 2001-01-16 The Regents Of The University Of Michigan High-resolution ionization detector and array of such detectors
US6281626B1 (en) * 1998-03-24 2001-08-28 Casio Computer Co., Ltd. Cold emission electrode method of manufacturing the same and display device using the same

Patent Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1520972A (fr) * 1966-04-30 1968-04-12 Beteiligungs & Patentverw Gmbh Source d'ions à émission par champ
DE2212424A1 (de) * 1971-03-25 1972-09-28 Cambridge Scientific Instr Ltd Elektronenkanone
US3786268A (en) * 1971-04-12 1974-01-15 Hitachi Ltd Electron gun device of field emission type
US3786305A (en) * 1972-05-15 1974-01-15 Hitachi Ltd Field emission electron gun
US3887835A (en) * 1972-06-09 1975-06-03 Hitachi Ltd Field emission electron gun
EP0601533A1 (de) * 1992-12-07 1994-06-15 Ricoh Company, Ltd Mikrovakuumvorrichtung
JPH0765696A (ja) * 1993-08-30 1995-03-10 Canon Inc 電子放出素子
FR2714208A1 (fr) * 1993-12-22 1995-06-23 Mitsubishi Electric Corp Cathode, canon à électrons comportant une telle cathode et tube à rayons cathodiques comportant un tel canon.
JPH09283065A (ja) * 1996-04-16 1997-10-31 Futaba Corp 電界放出型表示素子およびその駆動方法
EP0884762A1 (de) * 1997-06-13 1998-12-16 Commissariat A L'energie Atomique Spektrometer mit zwei verschiedenen Ionisationsvorrichtungen und Datenverarbeitungsverfahren dafür

Non-Patent Citations (4)

* Cited by examiner, † Cited by third party
Title
DAS J H ET AL: "MICROMACHINED FIELD EMISSION CATHODE WITH AN INTEGRATED HEATER", JOURNAL OF VACUUM SCIENCE AND TECHNOLOGY: PART B, VOL. 13, NR. 6, PAGE(S) 2432 - 2435, ISSN: 0734-211X, XP000558316 *
PATENT ABSTRACTS OF JAPAN vol. 013, no. 259 (E - 773) 15 June 1989 (1989-06-15) *
PATENT ABSTRACTS OF JAPAN vol. 199, no. 506 31 July 1995 (1995-07-31) *
PATENT ABSTRACTS OF JAPAN vol. 199, no. 802 30 January 1998 (1998-01-30) *

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Publication number Publication date
FR2792770A1 (fr) 2000-10-27
JP2000353492A (ja) 2000-12-19
US6559442B1 (en) 2003-05-06

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